*London J. 1903. The call of the wild. New York: Macmillian Publishers.
UNIVERSIDADE FEDERAL DO RIO GRANDE DO NORTE PROGRAMA DE PÓS-GRADUAÇÃO EM PSICOBIOLOGIA
The call of the (Neotropical) wild*: maned wolf long-range acoustic
ecology
LUANE MARIA STAMATTO FERREIRA
Orientadora: Profª. Drª. Renata Santoro de Sousa Lima
Co-orientador: Prof. Dr. Flávio Henrique Guimarães Rodrigues (UFMG)
NATAL – RN 2019
LUANE MARIA STAMATTO FERREIRA
The call of the (Neotropical) wild: maned wolf long-range acoustic
ecology
Tese de doutorado apresentada ao Programa de Pós-graduação em Psicobiologia do Centro de Biociências da Universidade Federal do Rio Grande do Norte, como parte dos requisitos para a obtenção do título de Doutor.
Orientadora: Profª. Drª. Renata Santoro de Sousa Lima
Co-orientador: Prof. Dr. Flávio Henrique Guimarães Rodrigues (UFMG)
NATAL – RN 2019
UNIVERSIDADE FEDERAL DO RIO GRANDE DO NORTE
Título da tese: The call of the (Neotropical) wild: maned wolf long-range acoustic ecology Autora: Luane Maria Stamatto Ferreira
Orientadora: Profa. Renata Sousa-Lima
Coorientador: Prof. Flávio Rodrigues Data da defesa: 28 de fevereiro de 2019 Parecer:
Banca examinadora:
Profa. Dr. Renata Sousa-Lima (presidente)
Universidade Federal do Rio Grande do Norte (UFRN)
Prof. Dr. Jeff Podos
University of Massachusetts Amherst
Prof. Dr. Holger Klinck Cornell University
Profa. Dra. Julie Patris
Aix-Marseille Université
Profa. Dra. Susan Parks
Agradecimentos
A aparente solitária e monumental tarefa de escrever uma tese é, na verdade, o trabalho de um exército e eu agradeço a todos que apoio por apoio, ideia por ideia, construíram esse projeto. Assim como o lobo-guará parece solitário, mas está inserido em uma rede social de comunicações, eu agradeço a vocês que foram, mesmo que alguns à longas distâncias, minha alcateia.
Agradeço primeiramente aos meus pais, Inês e Adir, pelo excepcional cuidado parental. Agradeço ao meu parceiro Carlos Carvalheira, que caminhou sempre ao meu lado. Agradeço a meu irmão Alessandro e sua parceira Sarah, que já dispersaram para Curitiba, mas sempre serão parte da alcateia. E também aos meus canídeos não selvagens, Neblina e Luke Luke.
Agradeço à minha família estendida, o Laboratório de Bioacústica da UFRN. Em especial aos lobos Victor Sábato (o primeiro lobo), Luciana Rocha (a primeira loba selvagem), Danielly Duarte, Edvaldo Neto, Thiago Pinheiro, Rafael Frigo, Flávio Rodrigues (o lobo-mor) e claro, à líder do grupo de caça, Renata Sousa Lima. Sem sua visão e orientação esse projeto não seria possível e nenhum lobo teria chegado tão longe.
Meus agradecimentos também vão a todos outros integrantes do LaB, mesmo os que ficaram por tempo breve. Vocês foram mais que colegas, foram amigos e família. Daqueles de mar e de terra, de rio e de ar, desde as intérpretes de baleiês, aos “ouvidores de tudo” (paisagem acústica), as lontras (e ariranhas), tartarugas, golfinhos, focas, saguis, passarinhos e gaviões. Meus agradecimentos especiais aos companheiros de aventura: Eliziane, Divna, Lara, Marcos e Letícia. E a todos colaboradores, Milagros Villavicencio, Júlio Baumgarten, Eduardo Venticinque e Mauro Pichorim.
Agradeço as pessoas que se disponibilizaram a ler e também contribuir com suas vozes no trabalho: Jeff Podos, Holger Klink, Julie Patris, Paulo Cordeiro, Susan Parks e Gustavo Zampier.
Agradeço as pessoas cujo apoio logístico e de know-how foi essencial ao projeto, em particular Jean Piere (que é afiliado do Dietz!), Ricardo, Marcello, Júlia Simões
(time 3m), Rogério Cunha de Paula e Flávio Rodrigues. Agradeço as pessoas fantásticas que conheci em São Roque de Minas, incluindo Adriano Gambarini e Flávia Ribeiro. Também aqueles que me ofereceram estadia nos momentos mais críticos: Renilda e funcionários da pousada Chapadão da Canastra, Pavel (melhor flash-touristic-guide de Ilhéus), Maria Inês Santoro (a mãe da Renata, que tem o mesmo nome da minha!), e Rachel e Gustavo, amigos de longa data (saudades). Me senti acolhida em todos sentidos.
Agradeço a CAPES pela bolsa, ao Programa de Pós-Graduação em Psicobiologia da UFRN pelo auxílio financeiro, ao ICMBio pela licença concedida e aos funcionários do centro administrativo do PNSC, em São Roque de Minas, por terem sido tão compreensivos e prestativos.
Agradeço de coração aos amigos que me mantiveram sã no processo, os grupos do RPG, boardgames, aikidô, séries (Lúcifer!), biologia (As Cobaias) e tantos outros. Um obrigada muito especial a Rodrigo, Thieza, Amanda, Aja, Fred Dimitrius, Geórgia, Girão, Ramon, Moal, Nicolau, Walles, Dinara, Suelen, Naíra, Carol e Nelson. E um
domo arigato gozaimashita ao meu sensei James!
Por fim, agradeço aos lobos-guará do Parque Nacional da Serra da Canastra que, mesmo sem terem assinado termo de consentimento livre esclarecido, tiveram suas conversas pessoais gravadas, dando, literalmente, voz a esse projeto. (Também espero que um dia eles tragam meu celular de volta).
Enfim, obrigada a todos.
Passamos por fogo e foi preciso ser ninja,
mas esta etapa está concluída!
Luane Maria Stamatto Ferreira 2019
For the strength of the Pack is the Wolf, and the strength of the Wolf is the Pack.
Abstract
Maned wolves are difficult to observe in the wild because of their low densities and their cryptic and crepuscular-nocturnal habits. Exploring their long-range call – the roar-bark – is an efficient alternative for studying the species. We used a combination of methodologies: we played back roar-barks in the wolves’ natural habitat to test how free-ranging animals would respond and to understand the propagation properties of this vocalization in the wild; we recorded spontaneous roar-bark sequences of wild maned wolves using a grid of autonomous recorders for eight months to reveal long term temporal patterns; and we used captive records to access sex and individuality in the roar-bark and to test its application to natural recordings. We found that maned wolves vocalize more during the beginning of the night, and this was the only period we obtained responses during the playback experiment, despite both twilights having efficient propagation of roar-barks. Social factors may be influencing the timing of the wolves’ long-range vocal activity. We suggest that roar-barks may be an honest
advertisement of quality for territorial defense. Maned wolves vocalize more on better moonlit nights, especially when the first half of the night is illuminated, likely as a consequence of reduced foraging time and therefore having more time to invest in acoustic communication. It was possible to identify the mating and circa-parturition period in our natural recordings by an increase in solo and group vocal activity, which suggests a role of roar-barks in partner attraction/guarding and intra-familiar-group communication. In captivity, male roar-barks were distinguishable by their longer duration, also indicating a sexual function and suggesting a higher energy investment to advertise motivation. Roar-barks were also individually distinct. However, site characteristics, such as presence of vegetation, drastically affected both the propagation of broadcasted roar-barks and most identity and sexual parameters’ transmission in the
wild. Elevating the speaker 45° upward to simulate the head/muzzle position during vocalization lead to lower recorded sound intensities, but partially counteracted the negative effects of vegetation on signal transmission. The few stable parameters were able to discriminate individuals, although with lower success rate. In wild recordings the variation of parameters due to propagation was larger than the variation due to individual differences, therefore limiting passive acoustic monitoring as a means of counting individuals in their natural habitats. Despite the present limitation of vocal identification in the wild, bioacoustic tools proved efficient in revealing the secretive behavior ecology of maned wolves.
Key-words: Chrysocyon brachyurus, canid, vocalization, sound propagation, passive acoustic monitoring, temporal patterns, playback.
Resumo
Os lobos-guará são difíceis de serem observados na natureza devido as suas baixas densidades e hábitos crípticos e noturno-crepusculares. Explorar seu chamado de longa distância – o aulido – pode ser uma alternativa eficiente para estudar a espécie. Usando uma combinação de metodologias: reproduzindo aulidos no ambiente natural da espécie para testar como animais de vida livre responderiam e para entender as propriedades de propagação dessa vocalização; gravando sequências de aulidos espontâneas de lobos-guará selvagens através de uma rede de gravadores autônomos por oito meses para revelar padrões temporais de longo prazo; e registramos os sons produzidos em cativeiro para conferir a discriminação de gênero e individualidade no aulido e testar sua aplicação em gravações de ambiente natural. Nós descobrimos que os lobos-guará vocalizam mais no início da noite, e esse foi o único período em que obtivemos respostas durante o experimento de playback, apesar de ambos crepúsculos apresentarem uma propagação eficiente deste tipo de som. Fatores sociais podem estar influenciando esse padrão temporal, como o anúncio honesto de qualidade para defesa territorial. Lobos-guará vocalizam mais em noites de maior iluminação lunar, especialmente quando a primeira metade da noite está iluminada, provavelmente como consequência de uma redução no tempo de forrageio e, portanto, mais tempo para investir na comunicação acústica. Foi possível identificar o período de acasalamento e aquele em torno do parto nas nossas gravações de ambiente natural através do aumento na atividade vocal solo e de grupo, o que indica um papel dos aulidos na atração/guarda de parceiros e na comunicação intra grupo familiar. Em cativeiro, os aulidos dos machos foram distinguíveis principalmente por sua duração mais longa, também indicando uma função sexual e sugerindo um investimento energético mais alto para anunciar motivação. Aulidos também foram distintos individualmente. Porém,
características locais afetaram dramaticamente tanto a propagação dos aulidos reproduzidos quanto quase todos parâmetros que conferem identidade e gênero aos sons emitidos. Elevar a caixa de som 45° para cima para simular a posição da cabeça/focinho durante a vocalização resultou em intensidades sonoras mais baixas nas gravações, mas compensou parcialmente os efeitos negativos da vegetação na transmissão do sinal acústico. Os poucos parâmetros estáveis durante a propagação em ambiente natural foram capazes de discriminar indivíduos, embora com menor taxa de sucesso. Infelizmente, nas gravações obtidas na natureza a variação dos parâmetros devido à propagação foi maior que as diferenças individuais observadas. Apesar da presente inaplicabilidade da identificação vocal em gravações de aulidos na natureza, as ferramentas bioacústicas se provaram eficientes em revelar a elusiva ecologia comportamental dos lobos-guará.
Palavras-chave: Chrysocyon brachyurus, canídeo, vocalização, propagação sonora, monitoramento acústico passivo, padrões temporais, playback.
Figure list
Figure A. Maned wolf. From: Paula & Gambarini 2013 (book) ……….………. 20 Figure B I. Maned wolf roar-barking. From: Paula & Gambarini 2013 (book) ……….………..… 23 Figure B II. Maned wolf (male “Nopal”) roar-barking at the Endangered Wolf Center in St. Louis, MO/U.S.A. Photo: Michelle Steinmeyer, 2015. ……….………….…….. 24 Figure B III. Radio collared maned wolf roar-barking. Photo: Flávio H. G. Rodrigues, 2011. ... 25 Figure C. Broadcasting (Pioneer S-DJ50X speaker) maned wolf roar-barks and re-recording them (SongMeter SM2+) at different distances (top: 03/07/2017) and deploying an autonomous recorder (from 13) to passively register spontaneous roar-barks sequences (bottom: 03/09/2016). Serra da Canastra National Park, Minas Gerais, Brazil. ……….……… 27
Chapter 1
Figure 1. Location of passive autonomous recorders and playback sites to study maned wolves at Serra da Canastra National Park, Minas Gerais, Brazil. Imagery ©2018 CNES / Airbus, Map data ©2018 Google…………...……….……. 34 Figure 2. Edited maned wolf roar-bark sequences used as stimuli for playback studies of maned wolves in the wild (Serra da Canastra National Park, Brazil). GA and SH are males, SA and JU are females. Top spectrograms are the original files (96 kHz sample rate, 32 bit wav, 4000 windows size, 56% brightness and 50% contrast) and the bottom a recording extracted from one autonomous recorder (Song Meter SM2+; Wildlife Acoustics) 80 meters from the playback speaker (8 kHz sample rate, 16 bit wav, 512 windows size, 50% brightness and contrast). Spectrogram made on Raven Pro 1.5……….…..….. 37 Figure 3. Distribution of wild maned wolf roar-bark sequences registered between March 04 and 11 2017 during a playback experiment at Serra da Canastra National Park, MG/Brazil. Each sequence is named by its start time and the size of the bar shows the time elapsed from the last broadcasted playback sequence. This time is also discriminated on tags above the sequences considered responses to the playback, i.e. those within 10 minutes after the end of any broadcasted sequence. ……….…..…... 42 Figure 4. Temporal distribution of maned wolf roar-bark sequences recorded at Serra da Canastra National Park, MG/Brazil, with autonomous recorders (Song Meter SM2+; Wildlife Acoustic). March 2017 (black line, left axis): percentage relative to the total (30 sequences) of vocal activity registered on continuous recordings of the 6 days in which the roar-bark playback experiment was conducted. March 2016 (dark gray bars, right axis): absolute number of sequences (total 224), 13 recorders, 20 nights, from 5 PM to 5 AM. April 2014 (light gray bars, right axis): absolute number of sequences (total 192), 12 recorders, 25 nights, from 6 PM to 6 AM (Rocha et al. 2016 dataset, used with permission). …...….…. 47 Supplementary Data SD1.Wild maned wolf roar-bark sequences recorded at Serra da Canastra National Park, MG/Brazil. a and b: sequence in response to a playback stimulus registered on 18:55:37 March 09 2017. c and d: two individuals (note the change in spectral characteristics after 33 s) recorded passively on 19:15:00 March 17 2016. Recordings made with autonomous recorders (Song Meter SM2+; Wildlife Acoustic), at 8 kHz sample rate and 16-bit wav file format. Spectrogram made on Raven pro 1.5 (Cornell Bioacoustics Lab, Ithaca, NY, USA), Hann window, 512 window size, 50% brightness and contrast, 50% overlap, smoothing on. .……….. ………...…… 59
Chapter 2
Figure 1. Study site at Serra da Canastra National Park, MG, Brazil. a - site Flat; b - site Low to high; c - site Vegetation; d - site High to low. Horizontal distance to the speaker is discriminated on the left side of the / and altitude on the right side. Maps constructed with QGIS 3.4.0-Madeira (QGIS Development Team, 2018. QGIS Geographic Information System. Open Source Geospatial Foundation
Project. http://qgis.osgeo.org) and Google Satellite images (Map data ©2018 Google, Imagery ©2018
TerraMetrics). ………..……….. 70
Figure 2. Captive maned wolves roar-barks sequences broadcasted at Serra da Canastra National Park, MG/Brazil. GA and SH are males, SA and JU females. Red selection boxes on the first roar-bark of each animal exemplifies the ones used to measure roar-bark intensity (peak power, dB). Selections near the second roar-bark of each animal exemplifies the ones used to measure noise intensity (average power, dB). Spectrograms and measures were made on Raven Pro 1.5 (Cornell Bioacoustics Lab, Ithaca, NY, USA), Hann window, 512 window size, 50% brightness and contrast, 50% overlap, smoothing “on”... 76
Figure 3. Propagation of broadcasted roar-barks from captive maned wolves at Serra da Canastra National Park, MG/Brazil. Re-recordings made with autonomous recorders (Song Meter SM2+; Wildlife Acoustics, Inc., Concord, Massachusetts). The intensity loss is relative to the re-recording at 1.25m …. 80 Figure 4. Propagation of broadcasted captive records of maned wolves roar-barks at 4 sites at Serra da Canastra National Park, MG/Brazil. Re-recordings made with autonomous recorders (Song Meter SM2+; Wildlife Acoustics, Inc., Concord, Massachusetts). The intensity loss is relative to the re-recording at 1.25m. ………...………...………...…………..…. 82
Figure 5. Propagation of broadcasted captive records of maned wolves roar-barks at 4 sites at Serra da Canastra National Park, MG/Brazil. We conducted broadcasts with the speaker box positioned straight forward (Straight) and with the speaker box inclined 45o upward (Inclined) to simulate the inclination of the head/muzzle seen when animals roar-bark. Re-recordings made with autonomous recorders (Song Meter SM2+; Wildlife Acoustics, Inc., Concord, Massachusetts). The intensity loss is relative to the straight re-recording at 1.25m. ………..….…… 84
Figure 6. Propagation of broadcasted captive records of maned wolves roar-barks at 6 time intervals at Serra da Canastra National Park, MG/Brazil. The time shown is the beginning of a 1 hour interval in which broadcasts were made. Re-recordings made with autonomous recorders (Song Meter SM2+; Wildlife Acoustics, Inc., Concord, Massachusetts). The intensity loss is relative to the re-recording at 1.25m……….………...……….. 85
1 – Preliminaty data exploration (supplementary material) ………..……….… 94
2 – Normality and homogeneity of residuals (supplementary material) ………...…………. 95
3 – Predicted x observed values of the model (supplementary material) ………...……..……. 96
Chapter 3 Figure 1. Study region at the Serra da Canastra National Park, MG/Brazil. Yellow squares indicate autonomous recorder (SongMeter SM2+) sites used only in 2014, pink triangles sites used only in 2016, and white circles sites used in both years. …………...……….…...… 107
Figure 2. Wild maned Wolf roar-bark sequences recorded passively with a grid of 12/13 autonomous recorders (Song Meter SM2+) at Serra da Canastra National Park, MG/Brazil. a) solo roar-bark sequence with detection boxes from XBAT (Figueroa 2007) extension for Matlab (MathWorks, Inc.). Spectrogram parameters: 512 window size, Hann window, 100% brightness, 43% contrast, 50% overlap on an 8 kHz sampling rate wav file. b) group vocalization consisting of two animals alternating roar-barks. Spectrogram made on Raven pro 1.5 (Cornell Bioacoustics Lab, Ithaca, NY, USA), Hann window, 512 window size, 50% brightness and contrast, 50% overlap, smoothing on, on an 8 kHz sampling rate wav file. ...………...… 111
Figure 3. Histogram of the number of roar-barks on each sequence of maned wolves’ vocalizations recorded passively with a grid of 12/13 autonomous recorders (Song Meter SM2+) at Serra da Canastra National Park, MG/Brazil. One sequence was defined by one or a bout of roar-barks not separated by more than 10 seconds. ………...……. 115
Figure 4. Seasonal variation in the maned wolf vocal activity recorded passively with a grid of 12/13 autonomous recorders (Song Meter SM2+) at Serra da Canastra National Park, MG/Brazil. Each point is a sum of 5 nights. Photos: Endangered Wolf Center, St.Louis, and Adriano Gambarini ……… 116 Figure 5. Maned wolf roar-bark sequences distribution over the lunar phases (gray = total). Records were made from April to July on 2014 (blue) and from March to June on 2016 (red) with a grid of 12/13 autonomous recorders (Song Meter SM2+) at Serra da Canastra National Park, MG/Brazil. The radial line represents the mean angle and the concentric bar at the end of the line the 95% confidence interval. …119 Figure 6. Maned Wolf roar-barks registered between 17-19h on passive audio recordings made with a grid of 12/13 autonomous recorders (Song Meter SM2+) at Serra da Canastra National Park, MG/Brazil. In 2014 there was no recordings in March, and in 2016 no recordings in July. ………….……….…… 121 Figure 7. Maned wolf nightly vocal activity relative to sunset. Recordings were made with a grid of 12/13 autonomous recorders (Song Meter SM2+) at Serra da Canastra National Park, MG/Brazil…… 122 Figure 8. Maned wolf roar-bark sequences recorded passively with 12 autonomous recorders (Song Meter SM2+) at Serra da Canastra National Park, MG/Brazil (gray contour). Circles have approximately 0.5 km radius with the center point being the recorder site. Heat colors represent the intensity of vocal activity (number of sequences). Letters indicates the site name and numbers following them on the circles indicates the amount of group vocalizations. * Indicates at least one sequence involved 3 animals (otherwise group vocalizations involve 2 animals).………...…...…... 124 Figure 9. Maned wolf roar-bark sequences recorded passively with 13 autonomous recorders (Song Meter SM2+) at Serra da Canastra National Park, MG/Brazil (gray contour). Circles have approximately 0.5 km radius with the center point being the recorder site. Heat colors represent the intensity of vocal activity (number of sequences). Letters indicates the site name and numbers following them indicates the amount of group vocalizations (sequences involving 2 animals). ….…………...………..…. 125 Figure S1. Nightly maned wolf roar-barks recorded passively with 12 autonomous recorders (Song Meter SM2+) at Serra da Canastra National Park, MG/Brazil (gray contour). From top-left to bottom-right: April 05/06/07/08 2014, April 15/16/17/18 2014, March 19/20/21/22/23 2016, and May 01/02/03/04 2016. **indicates at least one sequence of roar-barks involved two animals. *** indicates at least one sequence of roar-barks involved three animals. ………...………… 140
Chapter 4
Figure 1. Maned wolves roar-barks recorded in Minas Gerais, Brazil. a. One example of roar-bark from each of 10 individuals (letters) recorded with unidirectional microphone and a hand recorder in two captivity facilities. b. Roar-barks of GA and JU broadcasted and re-recorded with autonomous recorders at 7 different distances from the speaker on site “Flat” at the Serra da Canastra National Park. c. Free-ranging animals spontaneous roar-bark sequences recorded with autonomous recorders at the same park: top spectrogram shows some roar-barks (numbers) from a sequence involving two animals (letters); bottom spectrogram shows the same sequence recorded by another autonomous recorder 2.41 km away, roar-barks from “b” reach the recorders on different times because animals are at different positions. Spectrogram parameters: a. 96 kHz sample rate, 3080 window size, Hann window, 55% brightness, 60% contrast, 24-bit wav; b. and c. 8 kHz sample rate, 512 window size, Hann window, 50% brightness, 60% contrast, 16-bit wav. ………...… 152 Figure 2. First 3 linear discriminant functions for identity discrimination of 10 captive maned wolves (colors) roar-barks recorded from two facilities at Minas Gerais, Brazil. ………....…..……. 159 Figure 3. Differences in the roar-barks parameters between females and males maned wolves recorded in two facilities in Minas Gerais, Brazil. ………..………..…. 161 Figure 4. Variation of 8 selected parameters of broadcasted maned wolves roar-barks re-recorded at 7 distances (1.25-640m) at the Serra da Canastra National Park, MG/Brazil. ……….….………. 163
Figure 5. LDA percentage of correctly identity classification of broadcasted roar-barks of 4 maned wolves (bottom) re-recorded at 7 distances (1.25-640m) in 4 sites (top) at the Serra da Canastra National Park, MG/Brazil. ………..…...……. 164 Figure 6. Figure 6. Signal-to-noise ratio of broadcasted roar-barks of maned wolves re-recorded at 7 distances (1.25-640m) in 4 sites at the Serra da Canastra National Park, MG/Brazil. The signal-to-noise ratio was calculated subtracting from the in-band power of each roar-bark (150-2000 Hz) and the same measurement taken from an equal sized spectrogram portion immediately before the vocalization (measure of the background noise level). ………...………….… 165 Figure 7. Two different roar-bark sequences involving the same two maned wolves each (top), and their roar-bark parameters (bottom). Recordings made passively by two different autonomous recorders (SongMeter SM2+) at the Serra da Canastra National Park, MG/Brazil …………..……….…….. 168
Appendix I
Maned wolves do not emit more roar-barks than expected by chance during the illuminated versus the non-illuminated portion of the night, except from new to waxing crescent phase. In this phase only the first part of the night is illuminated, and thus the difference may be caused by the species preference to vocalize on this time. *t=2.906, df=33, p=0.006. Graph extracted and translated from: ÁRAUJO, D.D., FERREIRA, L.S., ROCHA, L.H.S., & SOUSA-LIMA, R.S. 2016. Influência do ciclo lunar nas vocalizações de lobo guará. Abstract and poster presentation at the III Conferência e VIII Simpósio de Psicobiologia, UFRN, Natal, Rio Grande do Norte, Brazil. ... 191
Appendix II
Individual variation of the time interval between the start of one maned wolf roar-bark to the next one in the sequence. Potential for Identity Coding (PIC; as in Robisson et al. 1993) for this parameter is 1.04. Data from 10 captive maned wolves, 24-124 roar-barks by individual, 897 roar-barks in total, recorded in 2010 by V.S. Rocha, at 2 facilities in Minas Gerais, Brazil ……… 192
Annex I
A sedated lactating maned wolf being examined by the Lobos da Canastra team. This female (known as “Rose”) was captured on the night between July 12-13 2016 at the Serra da Canastra National Park, around site F (Figure 1, Chapter 3). At this year she was already without a VHS collar, but her data shows she lived on the present study area since at least 2014, when she was first captured, also lactating. Photo: Rogério Cunha de Paula. Used with permission. ………...……. 193
Table list
Chapter 1
Table 1. Wild maned wolves’ vocal activity recorded by autonomous recorders (Song Meter SM2+; Wildlife Acoustics) at Serra da Canastra National Park, MG/Brazil, during the playback experiment days on 2017. Each row is a different roar-bark sequence. Those considered playback responses are underlined. Each playback session consisted of 8 broadcasted roar-bark sequences. The column “Heard?” indicates if the researchers, when present in loco, heard maned wolves’ calls ………. 43
Chapter 2
Table 1. ANOVA test for the fixed factors of the main model for the intensity (dB) loss of maned wolves roar-barks broadcasted on their natural environment. ...…………...………...…….. 78 Table 2. Approximate 95% confidence intervals for the estimate factor effects of the main model for the intensity (dB) loss of maned wolves roar-barks broadcasted on their natural environment. Base categories are specified under parenthesis. Factors/levels with positive and negative estimates, which indicates they are not influential on the model or not significantly different from the base category, are underlined………...………..…...…...… 79 Table 3. Simultaneous tests for general linear hypotheses using Tukey contrasts for multiple comparisons of means. The reported p values are adjusted by single-step method. Significance codes: 0 '***', 0.001 '**', 0.01 '*', 0.05 '.', 0.1 ' '. Only comparisons of consecutive distances are shown. ………...………… 81 Table S2. ANOVA test for the fixed factors of the secondary model for the intensity propagation of maned wolves roar-barks broadcasted on their natural environment. ……….…….. 97 Table S3. Secondary model: simultaneous tests for general linear hypotheses using Tukey contrasts for multiple comparisons of means. The reported p values are adjusted by single-step method. Significance codes: 0 '***', 0.001 '**', 0.01 '*', 0.05 '.', 0.1 ' '. Only com comparisons of consecutive distances are shown. ………...……….……..….. 97
Chapter 3
Table 1. Summary of maned wolf’s vocal activity recorded passively with a grid of 12/13 autonomous recorders (Song Meter SM2+) at Serra da Canastra National Park, MG/Brazil. ………...…..… 114 Table 2. Maned wolf vocal activity recorded passively with a grid of 12/13 autonomous recorders (Song Meter SM2+) at Serra da Canastra National Park, MG/Brazil. Values reported are mean by night ± SD. ………... 117 Table 3. Concentration of maned wolf vocal activity on each of eight moon cycles recorded passively with a grid of 12/13 autonomous recorders (Song Meter SM2+) at Serra da Canastra National Park, MG/Brazil. When the concentration is significant, the mean moon phase, mean angle ± circular standard deviation, and Rayleigh test statistics are reported. ………...……....… 120
Chapter 4
Table 1. Maned wolves recorded on 2010 at two facilities in Minas Gerais, Brazil. *estimated age. mx are non-participant males. m3 is GA/GI half-brother. ………..……. 148 Table 2. Selected parameters on maned wolves roar-barks (LSF analyst). “Full” measures refer to the roar-bark from 150 Hz to 2000 Hz, while “First” and “Second” bands refer to portions from lower to higher frequencies. Means±SD are for all 10 individuals, 20 roar-barks each. PIC = Potential for Identity
Coding (Robisson et al. 1993). (A) = unitless: proportion relative to entire duration. Parameters detailing can be found on Raven’s manual (Charif et al. 2010). ……….... 158 Table 3. Confusion matrix for the cross validation classification of 10 captive maned wolves by their roar-barks. Average from the classification results of two analysts (LF, VS), each constructed by means of the results from 1000 randomizations of 100 roar-barks (10 for each individual) from a total of 200. Extracted by the pDFA R function written by Roger Mundry (2015 version). ………..…………. 160 Table 4. ANOVA effect sizes (F) for the 8 selected parameters of 20 roar-barks from 4 maned wolves broadcasted and re-recorded at 5 distances (1.25-160m) in 4 sites. (A) = unitless: proportion relative to entire duration. α=0.0012. ………..…….…. 162 Table 5. Effect size (t) for the absolute difference between parameters of roar-barks from two different maned wolves vocalizing together (2 wolves) and roar-barks simultaneously recorded by two different autonomous recorders (2 recorders; SongMeter SM2+). 2 wolves: one sample t-test, df=91. 2 recorders: paired t-test, df=82. α=0.0012. Cor. SNR: Pearson’s correlation coefficient with the signal-to-noise ratio difference. (A) = unitless: proportion relative to entire duration. The vocalizations were recorded passively with a grid of 12/13 autonomous recorders at Serra da Canastra National Park, MG/Brazil... 167 Table 6. Mean±SD difference of the absolute difference between parameters of roar-barks from two different maned wolves vocalizing together (2 wolves) and roar-barks simultaneously recorded by two different autonomous recorders (2 recorders; SongMeter SM2+). Those differences were compared with a Welch two sample t-test. α=0.0012. (A) = unitless: proportion relative to entire duration. The vocalizations were recorded passively with a grid of 12/13 autonomous recorders at Serra da Canastra National Park, MG/Brazil. ………...…………...………....…. 167 Table S1. All measured parameters on maned wolves roar-barks (LSF analyst). “Full” measures refer to the roar-bark from 150 Hz to 2000 Hz, while “First” and “Second” bands refer to portions from lower to higher frequencies. Means±SD are for all 10 individuals, 20 roar-barks each. PIC = Potential for Identity Coding (Robisson et al. 1993). # selected for the identity classification. (A) = unitless: proportion relative to entire duration. *the selection box of the 2nd band is limited below by the selection box of the 1st band,
therefore we manually measured the 2nd band true lower frequency. Parameters detailing can be found on
Raven’s manual (Charif et al. 2010). ………..………..………..….…… 183 Table S2. Explained variance and coefficients of each linear discriminant function for identity discrimination of 10 captive maned wolves roar-barks. Non-normal parameters were transformed (Yeo Johnson). All parameters were centralized and scaled. ………....………….………….. 184 Table S3. ANOVA effect sizes (F) for all measured parameters on maned wolves roar-barks broadcasted and re-recorded at 5 distances (1.25-160m). “Full” measures refer to the entire roar-bark (from 150 Hz to 2000 Hz), while “First” and “Second” bands refer to portions from lower to higher frequencies. (A) = unitless: proportion relative to entire duration. α=0.0012. ………...……... 185
Summary
General introduction ... 20
Chapter 1... 28
Using playbacks to monitor and investigate the behavior of wild maned wolves ... 28
Abstract ... 29
Resumo ... 30
Introduction ... 31
Materials and methods ... 34
Results ... 42
Discussion ... 49
References ... 55
Supplementary data ... 59
Chapter 2... 60
Maned wolf long range call propagation and its implication for the species’ communication ... 60
Abstract ... 61
Resumo ... 62
Introduction ... 64
Materials and methods ... 69
Results ... 78
Discussion ... 86
References ... 90
Supplementary material ... 94
Chapter 3... 99
Temporal and spatial patterns of the long-range calls of maned wolves ... 99
Abstract ... 100
Resumo ... 101
Introduction ... 103
Material and Methods ... 107
Results ... 114
Discussion ... 127
Supplementary material ... 140
Chapter 4... 141
Identity and sex discrimination of roar-barks for captive and free-ranging maned wolves ... 141
Abstract ... 142
Resumo ... 143
Introduction ... 144
Material and Methods ... 148
Results ... 158 Discussion ... 169 References ... 177 Supplementary material ... 183 Final remarks ... 186 Extra-textual references ... 188 Appendix I ... 191 Appendix II ... 192 Annex I ... 193 Annex II ... 194
20
General introduction
The maned wolf (Chrysocyon brachyurus, Illiger, 1815; Figure A) is the only large canid of South America (Queirolo et al. 2007). The species is listed as Near Threatened by IUCN (IUCN 2015), Vulnerable in the Brazilian list of endangered species (Paula et al. 2013), and models predict a 30% reduction in populations in only 3 generations (21 years; Paula et al. 2008). The main threat to the species is the destruction of its habitat, the Cerrado neotropical savanna, which is one of the world’s most important biodiversity hotspots (Silva & Bates 2002).
Figure A. Maned wolf. From: Paula & Gambarini 2013 (book).
The maned wolfs’ iconic characteristics make it appealing to the public and a potential flagship species for the conservation of this biome (Myers et al. 2000). Its slender constitution and long legs are adapted to walk over the bushes and tall grass of its environment, while its large ears are used to detect hidden rodents and birds (Rodden
21
et al. 2004). This last characteristic also suggests that acoustic communication among individuals of this species over long distances might play a significant role.
Maned wolves present many typical canid characteristics, including nocturnal/crepuscular habits, some degree of territoriality, monogamous breeding with the formation of stable pairs, and biparental care of young (Rodden et al. 2004). However, “canid rules” state that larger canids (>13 kg) tend to be: more social, forming larger groups composed of the breeding pair and grown offspring; to have young cared by parents and helpers; to have large litter sizes; and to hunt cooperatively fot larger preys (Kleiman & Eisemberg 1973; Moehlamn 1987, 1989). Despite their size (20-30 kg, 70-90 cm; Silveira 1999), maned wolves tend to behave opposite than expected (Rodden et al. 2004): they forage alone for small vertebrates and fruits, the pair is rarely seen together, the presence of helpers have never been confirmed, and the litter size is small (captivity mean is 3; Maia & Gouveia 2002). They are normally described as less social than many small canids for which at least the breeding pair associates extensively, as with artic foxes (Frommolt et al. 2003), and crab eating foxes (Courtenay & Maffei 2004).
In comparison, the maned wolf closest living relative, the bush dog (Speothos
venaticus; Slater et al. 2009), is highly social and also an exception to canid rules, in the
other direction (as it is small: 4-7 kg; Beisiegel & Ades 2002). They are hypercarnivores and hunt cooperatively for large prey (Kleiman 1972; Beisiegel & Ades 2002), which highlights the relationship of feeding habits and canid social systems and indicates canid rules may not be widespread. The small items’ diet of the maned wolf makes sharing unprofitable and the presence of conspecifics may interfere in foraging (McNab 1986). Accordingly, Melo et al. (2007) reports that a breeding pair and a juvenile slept relatively close during the day but stayed far apart during the active hours (i.e., night).
22
This last study also suggests a higher intra-group (pair and occasional offspring) association than previously though. Despite telemetry studies usually not showing so (Jácomo et al. 2009), there are several instances of group bonding/socialization: reports of a breeding pair sleeping together (Melo et al. 2009; Emmons 2012); cooperative hunting (Jácomo et al. 2009); males accompanied by young (Rodrigues 2002); males providing or regurgitating to the female and pups (Dietz 1984; Jácomo et al. 2009), including regurgitation to 5-9 month young in captivity (Rasmussen & Tilson 1984); and a group composed of the breeding pair and 3 juveniles that interacted often (Emmons 2012). On Emmons’ (2012) work, the long-range acoustic communication was very important for these interactions.
Maned wolves use multiple communication modalities (Rodden et al. 2004), as visual (e.g. piloerection, gape, ear and tail positioning) and chemical (e.g. urine, feces, scent marks). The acoustic communication channel is also expected to be exploited by the species, especially considering the limitations of visual signaling in a crepuscular/nocturnal and solitary animal (Fox 1975). The species has a complex acoustic repertoire, including at least 10 types of vocalizations and combinations of vocalizations (Sábato 2011). Maned wolves’ vocal repertoire comprises almost all canid broad categories of vocalizations (Tembrock 1976), which points to complex social interactions, as social and vocal complexity are generally linked (Freeberg 2006). The most frequent type of vocalization recorded in captivity is the long-range roar-bark (Sábato 2011; Figure B I-III), a call heard throughout the year in the wolves’ natural habitat (Rodden et al. 2004). Thus, maned wolves may be solitary, but seem to maintain social acoustic contact over distance.
Roar-barks are emitted in sequences of 5-15 units, spaced by 3-5 seconds, and are proposed to have multiple functions. One of the most cited is territorial
23
announcement (Kleiman 1972; Rocha 2011), especially for same-sex spacing (Brady 1981). Maned wolves from adjacent ranges have been heard exchanging roar-barks and emitting them when facing threats (conspecifics and humans; Dietz 1984), and in captivity, same sex individuals often exchange roar-barks (Brady 1981; Sábato 2011).
24 Figure B II. Maned wolf (male “Nopal”) roar-barking at the Endangered Wolf Center in St. Louis, MO/U.S.A. Photo: Michelle Steinmeyer, 2015.
25 Figure B III. Radio collared maned wolf roar-barking. Photo: Flávio H. G. Rodrigues, 2011.
The other function often cited for the roar-bark is in intra-pair communication (Rocha et al. 2016; Balieiro & Monticelli 2019), being more important during the breeding season (Dietz 1984), even in captivity (Sábato 2011). Researchers report that between roar-barks maned wolves aurally attend to answers (Emmons 2012) and search visually for the partner (Bestelmeyer 2000), that during estrous they emit roar-barks whenever the partner is outside of visual range (Rodden et al. 2004), that often the partner appears after the vocalization or move towards it (Bestelmeyer 2000; Emmons 2012), and pairs have been heard exchanging roar-barks many times (Dietz 1984; Sábato 2011; Emmons 2012; Balieiro & Monticelli 2019). Some authors thus propose the intra-group (pair and occasional offspring) communication would be the main roar-bark function (Emmons 2012).
Roar-barks are considered far ranging, with Brady (1981) stating a human could discriminate individuals over 1 km. Indeed, it was the only maned wolf vocalization we could detect with passive autonomous recorders in the wild (Rocha et al. 2015, 2016).
26
Maned wolves are more easily heard than visualized (Emmons 2012; personal observation), and usually very hard to follow due to their shyness, habitat composition, and crepuscular/nocturnal habits (Rodden et al. 2004). Thus, exploring their long-range acoustic communication might be an efficient alternative to monitor populations and elucidate the species behavior ecology. The potential for vocal individualization makes the bioacoustics approach even more interesting.
In this work I explored the maned wolf long range acoustic communication to better understand the species’ behavioral ecology. I did it through three complimentary
methodologies (Figure C). First, I conducted a roar-bark playback experiment in the wolves’ natural habitat. The experiment had a dual objective: to test if, and how, wild
maned wolves would respond to roar-bark playbacks, assessing both evidence of its function and monitoring applicability (chapter 1); and to understand how the roar-bark propagates over distance, also testing if some behaviors, like period of the day and night and head elevation, were related to acoustic propagation (chapter 2). Second, I passively recorded spontaneous (non-playback elicited) roar-barks sequences of wild maned wolves using 12/13 autonomous recorders during eight months over two years (2014 and 2016). Those recordings generated an enormous dataset (over 3.5 TB), that was processed by automatically detecting roar-barks through a previously established method (Rocha et al. 2015: 100% of detections in half the time x 92% for visual inspection of spectrograms). The primary goal of those wild recordings was to characterize the maned wolf seasonal, lunar and nightly roar-bark emission patterns (chapter 3). Finally, I used the experimentally broadcasted roar-barks, the naturally spontaneous vocalization recordings, and roar-barks recorded in captivity by V. Sábato (2011) to confirm roar-bark individual and sexual discriminability through permuted
27
discriminant analyses and, more important, test the applicability of vocal individualization in recordings from the wild (chapter 4).
Figure C. Broadcasting (Pioneer S-DJ50X speaker) maned wolf roar-barks and re-recording them (SongMeter SM2+) at different distances (top: 03/07/2017) and deploying an autonomous recorder (from 13) to passively register spontaneous roar-barks sequences (bottom: 03/09/2016). Serra da Canastra National Park, Minas Gerais, Brazil.
Examples of maned wolf roar-bark sequences recorded in this work can be heard
in https://soundcloud.com/luane-ferreira-327256713. Visual and acoustic data collection
at this park was authorized by Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio; SISBIO license number 41329-2, annexed in the end of this text).
28
Chapter 1
Using playbacks to monitor and investigate the
behavior of wild maned wolves
29
Using playbacks to monitor and investigate the behavior of wild maned
wolves
Luane Stamatto Ferreira, Júlia Simões Damo, Victor Sábato, Júlio Baumgarten, Flávio H. G. Rodrigues, Renata S. Sousa-Lima
Intended for submission to: Mastozoologia neotropical
Abstract
Maned wolves are difficult to observe in the wild because of their low densities and their cryptic and crepuscular-nocturnal habits. Exploring their long-range acoustic communication may offer an efficient alternative to study the species. Here we evaluated the applicability of playbacks to study maned wolves in the wild and compare the results with 20 nights of passive recordings on the same area and month during the previous year. We obtained vocal responses on 3 of 6 nights tested, including responses involving two animals and an approach after an interactive playback. Although we conducted 3-6 playback sessions each day at different times, we only obtained vocal responses during sessions between 17:00 and 19:40. During our passive recordings we detected on average 0.86 roar-bark sequences per recorder per night, mostly during the first half of the night. Vocal activity – responses and spontaneous roar-bark sequences – during playback nights was nearly 4 times greater than during the passive recordings. We conclude that playbacks stimulate maned wolves to emit roar-barks and that this method is applicable to test hypotheses about maned wolf behavior and aid in their monitoring.
30
Resumo
Lobos guará são difíceis de serem observados na natureza devido às suas baixas densidades e hábitos crípticos e crepusculares-noturnos. Explorar sua comunicação acústica de longo alcance pode oferecer uma alternativa eficiente para estudar a espécie. Neste trabalho nós avaliamos a aplicabilidade de usar playbacks para estudar lobos guará na natureza e comparamos estes resultados com 20 noites de gravações passivas na mesma área e mês durante o ano anterior. Obtivemos respostas vocais em 3 das 6 noites testadas, incluindo respostas envolvendo dois animais e uma aproximação depois de um playback interativo. Apesar de termos conduzido 3-6 sessões por dia em diferentes horários, nós só obtivemos respostas vocais em sessões entre 17:00 e 19:40. Durante as gravações passivas nós detectamos em média 0.86 sequências de aulidos por gravador por noite, a maioria na primeira metade da noite. A atividade vocal – respostas e sequências de aulidos espontâneas – durante as noites de playback foi quase 4 vezes maior que durante as gravações passivas. Nós concluímos que playbacks estimulam os lobos guará a emitir aulidos e que o emprego deste método e viável para testar hipóteses sobre o comportamento do lobo guará e auxiliar seu monitoramento.
Key words: Chrysocyon brachyurus, maned wolf, passive acoustic monitoring, playback, roar-bark, vocal activity, vocalization time
31
Introduction
The maned wolf (Chrysocyon brachyurus; Illiger, 1815) is South America's largest canid (80-90 cm shoulder height and 20-30 kg in weight; Rodden et al. 2004; Jácomo et al. 2009). These animals forage alone for fruits and small vertebrates (Queirolo and Motta-Junior 2007). Maned wolves form stable breeding pairs that share an extensive home range (15-115 km2; Rodrigues 2002; Azevedo 2008). Unlike other large canids, the pair is thought to rarely interact outside the breeding season (Dietz 1984; Rodden et al. 2004; Jácomo et al. 2009). From estrus to the weaning of young, the pair may sleep together (Melo et al. 2007), encounter frequently, and travel or forage together for several hours (Rodden et al. 2004; Emmons 2012).
Maned wolves communicate acoustically throughout the year using a long-distance vocalization called the roar-bark, normally uttered in sequences (bouts) of 5-15 repetitions (see spectrograms in Materials and Methods; Rodden et al. 2004; Rocha et al. 2016). The proposed functions of roar-barks are intra-pair and parent-offspring communication, opposite-sex attraction and same-sex repelling, and/or territorial announcement (Brady 1981; Dietz 1984; Sábato 2011; Emmons 2012; Rocha et al. 2016).
Few studies have been conducted observing maned wolves in the wild because of their low densities and of their cryptic and crepuscular-nocturnal habits (Jácomo et al. 2004; Melo et al. 2007; Trolle et al. 2007). As the species is difficult to visualize and follow, exploring their long-range acoustic communication may be an efficient alternative to fill the many gaps in the knowledge of their behavior, and to monitor their distribution and population trends (Marion et al. 1981; Rodden et al. 2004; Blumstein et al. 2011).
32
Grids of autonomous audio recorders mounted for extended periods have been
used to investigate many aquatic species that cannot be easily observed, as most cetaceans (e.g. humpback whales - Megaptera novaeangliae: Sousa-Lima and Clark
2008; beaked whales - Mesoplodon densirostris: Marques et al. 2009; minke whales -
Balaenoptera acutorostrata: Risch et al. 2013). For terrestrial environments, birds
dwelling in dense forests (Mennill and Vehrencamp 2008), nocturnal remote-nesting birds (Oppel et al. 2014), and widely dispersed forest mammals (e.g. elephants -
Loxodonta africanacyclotis: Thompson et al. 2010), have also been studied with passive acoustic monitoring. This methodology has already proven useful in the investigation of wild maned wolves. The recording of 32 nights (8/month) suggests they vocalize more often in the mating season, in the beginning of their activity period (first hour of the night), and less often during new moon nights (Rocha et al. 2016).
Playbacks, different from passive acoustic monitoring, offers a more direct way of testing hypothesis about the species behavior, and can possibly reduce monitoring effort by stimulating immediate and higher vocal activity and inducing approaches to facilitate detection or captures. Playbacks have long been used to study the behavior and monitor populations of primates (Radick 2005) and birds (e.g. Lanyon 1963; Marion et al. 1981). Today its use is widespread across taxa including insects, anurans (Greenfield 1994), and carnivores, such as lions and hyenas (Panthera leo, Crocuta crocuta; Cozzi et al. 2013). This technique has been successfully employed to study other canids in the wild, including wolves (Canis lupus; Harrington 1987; Brennan et al. 2013), coyotes (Canis latrans; Petroelje et al. 2013), swift foxes (Vulpes velox; Darden and Dabelsteen 2008), and bush dogs (Speothos venaticus; DeMatteo et al. 2004), but remained untested for maned wolves.
33
Here we evaluated the applicability of playbacks to study maned wolves in the wild through the broadcast of roar-bark sequences to elicit responses from free-ranging animals. We tested different broadcasting hours aiming to guide the planning of future playback efforts, and to identify the best period of the day for conducting an interactive playback aiming to escalate the animals’ response and induce approaches to the speaker. If maned wolves are responsive to playbacks, future investigations could test how the species use roar-barks, e.g. if sexes respond equally to male and female broadcasted roar-barks, or survey maned wolves’ presence and distribution in a practical way. If maned wolves are also shown to be attracted to the playback, this can be used to permit their detection, even if they do not respond vocally, count individuals, and improve capture chances. Additionally, we tested the use of autonomous recorders to increase the probabilities of registering responses and identifying local roar-bark range (and other propagation effects whose results are not shown here). Determining the roar-bark range is important to make playback sites independent and to estimate the surveyed area, while estimating our roar-bark detection capabilities will serve to plan how effectively we can survey an area.
Playback results were compared with nightly detections of roar-barks from passive acoustic recordings in the same area on the same month of the previous year. Although there are no residency studies for the species, it is likely that the same individuals were residing the area. Long term research suggests that individuals occupy the same territories from 3 to 5 years (ranging from 1 to over 9 years; Emmons 2012). The passive acoustic pattern of detection were used to establish a baseline level of roar-bark spontaneous emissions along the night to test if playbacks would increase vocal activity or change the temporal emission pattern.
34
Materials and methods
1. Study areaWe conducted this study at Serra da Canastra National Park, Minas Gerais state, Brazil (Figure 1). The park is mainly composed of Cerrado open savannas with a cold, dry season (April-September) and a hot, rainy season (October-March; Queirolo and Motta-Junior 2007).
Wild maned wolf acoustic data collection at this park was authorized by Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio; SISBIO license number 41329-2) and playback experiments were done in accordance with the ASM guidelines
(Sikes et al. 2016).
Figure 1. Location of passive autonomous recorders and playback sites to study maned wolves at Serra da Canastra National Park, Minas Gerais, Brazil. Imagery ©2018 CNES / Airbus, Map data ©2018 Google.
35
2. Playbacks
Roar-barks used as stimuli were obtained from two facilities in Minas Gerais state that keeps captive maned wolves: Criadouro Científico de Fauna Silvestre para
Fins de Conservação da Companhia Brasileira de Metalurgia e Mineração, and Zoológico da Associação Esportiva e Recreativa dos Funcionários das Usinas Siderúrgicas de Minas Gerais. Recordings were conducted between April and June
2010 and November 2010, respectively. The sounds were recorded 5-8 m from the animals with a unidirectional microphone Sennheiser K6 coupled to a Sennheiser ME-66 module and connected with a solid-state recorder Marantz PMD-ME-661, using a 96 kHz sample rate, and a 24-bit wav coding form.
To set the intensity level we used the playback equipment (described below) to broadcast the captivity recordings and then re-record the played back sounds with the same equipment and settings used for the original captivity recordings at the same distance the focal animals were. We then changed the speaker volume until the roar-bark intensity measured in the re-recordings matched the intensity measured in the original captivity recordings (measures made in Raven Pro 1.5 software: Bioacoustics Research Program, 2014. Raven Pro: Interactive Sound Analysis Software. Ithaca, NY: The Cornell Lab of Ornithology). This was our solution to achieve a playback intensity level as similar as maned wolves' roar-bark emission. During the recordings in captivity we did not have a direct way to measure sound pressure levels, and thus no means of calculating absolute source intensity levels. Two experienced researchers, including the author of the original captivity recordings (VS), reported the playback sounded as strong as heard from the animals in captivity and in the wild (FHR).
Playbacks sessions were conducted in three different sites in the park (Figure 1) between March 4 and 9, 2017. We used an Acer AspireOne notebook to broadcast the
36
sounds using Raven Pro 1.5 software and a Pioneer S-DJ50X speaker (class A/B Bi-amp, 80 W output, 50-20000 Hz frequency range) 86 cm above the ground to simulate the height of a maned wolf.
We used 4 edited roar-bark sequences including sounds from two males and two females (Figure 2). Recordings of both sexes were used to maximize the chance of response. Each sequence was composed of 5 roar-barks separated by 2.9-6.2 seconds (similar to the natural emission for an individual) and intervals between sequences varied from 10 seconds to 10 minutes depending on weather conditions. In each playback session, all four individual sequences were played in random order and then repeated once, resulting in complete sessions being composed of 8 sequences of 5 roar-barks each and lasting 5-25 minutes in total. If we heard an answer from a wild maned wolf before finishing the broadcast of all sequences we broadcasted the next sequence right after the response aiming to create an interactive playback. This was done trying to stimulate the responsive animal’s approach.
37 Figure 2. Edited maned wolf roar-bark sequences used as stimuli for playback studies of maned wolves in the wild (Serra da Canastra National Park, Brazil). GA and SH are males, SA and JU are females. Top spectrograms are the original files (96 kHz sample rate, 32 bit wav, 4000 windows size, 56% brightness and 50% contrast) and the bottom a recording extracted from one autonomous recorder (Song Meter SM2+; Wildlife Acoustics) 80 meters from the playback speaker (8 kHz sample rate, 16 bit wav, 512 windows size, 50% brightness and contrast). Spectrogram made on Raven Pro 1.5.
We conducted playbacks on two nights at each site, except on site A where we could only do it once (March 04 to 05) due to logistical issues. Sessions were conducted three times each night at the following moments: After Sunset (between 15 and 75
38
minutes after sunset), Midnight (between 23:00 and 00:00), and Before Sunrise (between 15 and 75 minutes before sunrise). Due to weather conditions, on the first night (March 07 to 08) at site C we could not do the After Sunset session, and compensated for it by conducting a session on a third consecutive night (March 09). At site C we conducted additional diurnal sessions on two days (March 08 and 09) three times each day to tests the animals’ responsiveness during the light period: After
Sunrise (between 15 and 75 minutes after sunrise), Midday (between 11:00 and 12:00), and Before Sunset (between 15 and 75 minutes before sunset). Mean local sunset was 18:28 and sunrise 06:05 during the playback days (calculated on https://www.sunearthtools.com/pt/solar/sunrise-sunset-calendar.php; access Set/16 2018). This experimental design resulted in a total of 21 playback sessions over 6 days. During the conducted playback sessions wind speed was 0.37 ± 0.61 m/s (mean ± SD, maximum 2.4 m/s), which based on our previous work should not significantly impact roar-bark detection and propagation (Rocha et al. 2016).
Roar-bark sequences of free-ranging maned wolves detected up to 10 minutes after the end of any broadcasted sequence were considered responses to the playback. Although it is impossible to differentiate a vocal response from a spontaneous vocalization, we consider 10 minutes a plausible interval to assume the vocalization is an playback-elicited answer as maned wolves vocalize 0.41 roar-bark sequences per night per recorder in the wild (Rocha et al. 2016) and 0.68 sequences per individual per night in captivity (Sábato 2011). The chance of a maned wolf spontaneously emitting a roar-bark sequence within any given 10 minutes each night is less than 1% (0.57% based on Rocha et al. 2016; 0.94% based on Sábato 2011).
For each response we recorded the time of emission and, based on the vocalization source direction determined by ear, if there were more than one animal
39
vocalizing. Additionally, we waited at least 30 minutes after the end of each session near the playback site to verify possible approaches by responsive animals.
3. Autonomous recordings during the playback experiment
We successively mounted at each playback site a line of 8 autonomous recorders (Song Meter SM2+; Wildlife Acoustics, Inc., Concord, Massachusetts) with one omnidirectional weatherproof microphone each (SMX-II; Wildlife Acoustics, Inc.; sensitivity -36±4dB [0dB=1V/pa@1kHz]; 20Hz-20kHz flat response frequency). Recorders were set on the road side in a single direction from the playback speaker positioned at distances of 1.25 m, 20 m, 40 m, 80 m, 160 m, 320 m, 640 m, and 1280 m. Distances were measured using a tape measure (1.25 to 80 m) and a GPS (Garmin GPSMAP® 76S; accuracy < 15 m). The autonomous recorders were attached on stakes of the same height of the speaker (86 cm) with the omnidirectional microphone in a perpendicular position in relation to the speaker. Recordings were made continuously, with an 8 kHz sample rate, 16-bit wav files, and partitioned in 30 minutes files.
At site A the autonomous recorders were active from 16:34 March 04 to 06:04 March 05 (total 13 h 30 min), at site B from 16:03 March 05 to 08:33 March 07 (total 40 h 30 min), and at site C from 19:03 March 07 to 06:33 March 11 (total 83 h 30 min). After the end of the experiment we left the recorders active for an extra day and night (March 10 to 11), resulting in the larger amount of recording hours at site C. We used this extra day and night to evaluate if maned wolves would continue to vocalize spontaneously without the playback stimuli.
We automatically detected roar-barks on the files using the methodology detailed in Rocha et al. (2015). This methodology uses XBAT_R7 (Extensible Bioacoustics Tool; Figueroa 2007) extension for MATLAB (R2010a version; MathWorks, Inc., Natick, MA, USA) to generates spectrograms of the files that are
40
subjected to a cross correlation tool employing 4 roar-bark templates. Matches above a pre-defined threshold (0.21) are then manually verified for false positives and undetected roar-barks within 24 seconds of the detected ones.
We detected both free-ranging maned wolves roar-barks and the roar barks we broadcasted during the playback. For the broadcasted roar-barks we noted all recorders that registered the calls (e.g. 1.25 m, 20 m, 40 m, etc.). We used this information to estimate roar-bark range. To do so we used only the playbacks conducted at night, as maned wolves rarely vocalize during the daylight period (Brady 1981; Emmons 2012).
For free-ranging maned wolves roar-bark sequences we noted the time of emission, time from the end of the last broadcasted roar-bark sequence (equivalent to the latency in the cases considered responses), the number of roar-barks in the sequence, the distance of the autonomous recorder that the roar-bark recording was most intense (measured by the peak power function of Raven pro 1.5), and if the vocalizations were heard by us in the cases we were present at the site near the speaker. The maximum interval between roar-barks that we considered a single sequence was 10 seconds, longer intervals were considered the beginning of a different sequence (based on Rocha et al. 2016 dataset and Bender et al. 1996).
4. Comparative passive acoustic monitoring
In 2016 we deployed 13 autonomous recorders (Song Meter SM2+, Wildlife Acoustics; 8 of which were the same ones used during the 2017 playback experiment) at Serra da Canastra National Park on the same region that we conducted the playback experiments (Figure 1). Mean distance between recorders was 3.03 km (minimum 2.16 km, maximum 3.90 km). Recorders were attached onto 1.4 m wooden stakes to maximize detections of roar-barks and were set with the same recording configurations as the playback experiment but programed to record from 5 PM to 5 AM each day.
41
Considering our previous study in the area (Rocha et al. 2016) we expected this period to comprise most of the maned wolf vocal activity. Recordings were made during 20 consecutive nights between March 09 and 28, 2016.
Roar-bark sequences were automatically detected on the audio files the same way we did with the playback recordings. For each roar-bark sequence found we noted time of emission, the number of roar-barks in the sequence, recorder location, and if the sequence was recorded by more than one recorder. That last information was verified comparing the sequences´ time of emission and the inter roar-barks intervals, which is unique for each sequence and ensures it is the same sequence recorded in two (or more) recorders and not two independent sequences of different animals vocalizing at the same moment. We only counted the most intense record of a sequence that has been detected in multiple sensors. Finally, we measured the time interval between sequences emitted in the same recorder during the same night.
In some cases we could identify a second animal started a roar-bark sequence before the end of another animal sequence, resulting in intercalated roar-barks. We could recognize the presence of a second animal based on differences in roar-bark cadence, intensity, spectral shape, and occasional overlap of roar-barks. If roar-bark sequences were separated (no intercalated roar-barks) and there was no striking spectral shape difference between them we could not tell if the sequences were emitted by the same or different animals. In cases of two animals vocalizing at the same moment we considered the interval between the sequences as 0 seconds.
42
Results
1. Playback experiment and recordings
The results from the playback experiment are summarized in Table 1 and Figure 3. All roar-bark sequences heard in loco by the researchers were recorded by at least one autonomous recorder. We were not able to visualize the animals.
We obtained vocal responses in only 4 of 21 playback sessions (see Supplementary data SD1 and SD 2 for examples of such responses). Responses occurred in 3 of 6 nights in which there was at least one playback session. On 2 nights the “After Sunset” playback session was answered and on one night both the “Before Sunset” and “After Sunset” sessions elicited vocal responses. Responses consisted of
1-3 roar-bark sequences on average 02:12 ± 01:56 minutes (X̅ ± SD; N = 8) after the end of the broadcasted sequence.
Figure 3. Distribution of wild maned wolf roar-bark sequences registered between March 04 and 11 2017 during a playback experiment at Serra da Canastra National Park, MG/Brazil. Each sequence is named by its start time and the size of the bar shows the time elapsed from the last broadcasted playback sequence. This time is also discriminated on tags above the sequences considered responses to the playback, i.e. those within 10 minutes after the end of any broadcasted sequence.
