Steven SON 1,2, Frank CEZILLY 2 & Jean-Raphaël GROS-DESORMAUX 1

Transcription

1 Steven SON 1,2, Frank CEZILLY 2 & Jean-Raphaël GROS-DESORMAUX 1 1 Université des Antilles, UMR CNRS 8053 L.C.2.S., Martinique 2 Université de Bourgogne, UMR 6282 Biogéosciences, Dijon, France 1

2 The White-Breasted Thrasher Ramphocinclus brachyurus (Temple et al., 2006, Mortensen et al., 2014, 2016, In prep.) Mimids family (Mimidae) Two islands and two subspecies White-breasted thrasher (Ramphocinclus brachyurus sanctaelucia) White-breasted thrasher (Ramphocinclus brachyurus brachyurus) Photos by Jennifer Mortensen 2

3 The White-breasted Thrasher in Martinique : Naturalist accounts Gros-Désormeaux et al. (2015) Gaps in knowledge Demography Sex-ratio (Cooperative breeding) Behavior Distribution of the White-Breasted Thrasher in Martinique - Map 3

4 Initiating a Capture -Mark-Recapture program Sexing of individuals (molecular methods) Health (body condition and infection with blood parasites) Vigilance behavior and foraging efficiency 4

5 Current distribution of the White-Breasted Thrasher. Map Distribution of White-Breasted Thrasher population of Caravelle Peninsula. Green : Caravelle Nature Reserve. Brown: Morne Pavillon and Anse Spoutourne 5

6 840 hours of capture sessions 6

7 Blood sampling (brachial vein) and molecular analyses Sexing of individuals Infection with blood parasites Body condition (Peig & Green, 2009) 7

8 Video recordings ( total time spent prospecting: 196 hours) Behavioural sequences alternating between: Vigilance (V) Scratching (S) Eating (E) Quantification: Vigilance rate (number of scans/time unit) Capture effort (number of scratches/prey captured) 8

9 Video recordings ( total time spent prospecting: 196 hours) Behavioural sequences alternating between: Vigilance (V) Scratching (S) Eating (E) Quantification: (22 different recordings, about one hour in total duration) Vigilance rate Capture effort Risk of pseudoreplication Only one banded bird Mantel tests: Test for data independence (Katzner et al., 2006) Multiple observations of the same individual Spatial variation in predation risk and/or prey abundance 9

10 Population size and sex-ratio 38 White-Breasted Thrashers 11 females and 27 males (binomial test, Pobs = ; p-value = ; CI95% =[0.5410;0.8458]). Sex differences Significant difference in weight between males and females, independently of capture site (inside versus outside the reserve) (F3,34= 8.913, p-value = 0.01). Body mass of White-Breasted Thrashers function of the sex and the sampled site. 10

11 Comparison of individual quality between sites Tarsus length of birds in the reserve versus outside of it. No difference in body condition. Parasitism Of 38 White Breasted Thrashers, only 2 (5.2%) were infected with Plasmodium spp. Tarsus length of White-Breasted Thrashers function of the sampled area. (t36 = 3.413, p-value = 0.002; Cohen s d = %CI = [ ;2.0511]) 11

12 Vigilance rate and capture effort 22 video recorded lasting one hour. Mantel tests: No correlation between behavioral distances and spatial distances. Independence of data No spatial autocorrelation Table: Results of Mantel tests. Parameter r p-value Distance between vigilance rates Distance between capture efforts

13 Vigilance rate and capture effort N=22 Vigilance rate (scans/s): µv=0.17,[ ] Capture effort (scratches/prey): µc=6.5,[ ] Capture effort as a function of Vigilance rate 13

14 Biased sex ratio and body condition Random variation? Cooperative breeding? (Varian-Ramos et al., 2010; Gressler et al.,2014) Higher tarsus length within the Reserve Habitat quality (better growth conditions)? Need for additional data. 14

15 Vigilance rate and foraging effort Reliability of the method Influence of spatial variation in predation risk? Influence of spatial variation in human disturbance? 15

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17 Gressler, D. T., da Paz Pereira, Z., & Marini, M. Â. (2014). Brood sex allocation in the neotropical cooperative White-banded Tanager Neothraupis fasciata. Journal of ornithology, 155, Katzner, T. E., Bragin, E. A., Knick, S. T., & Smith, A. T. (2006). Spatial structure in the diet of imperial eagles Aquila heliaca in Kazakhstan. Journal of avian biology, 37, Mittermeier, R. A., Myers, N., Thomsen, J. B., Da Fonseca, G. A., & Olivieri, S. (1998). Biodiversity hotspots and major tropical wilderness areas: approaches to setting conservation priorities. Conservation biology, 12, Myers, N., Mittermeier, R. A., Mittermeier, C. G., B. da Fonseca, G., & Kent, J. (2000). Biodiversity hotspots for conservation priorities. Nature, 403, Peig, J., & Green, A. J. (2009). New perspectives for estimating body condition from mass/length data: the scaled mass index as an alternative method. Oikos, 118, Pimm, S. L., Russell, G. J., Gittleman, J. L., & Brooks, T. M. (1995). The future of biodiversity. Science-AAAS-Weekly Paper Edition, 269, Reed, D. H., O Grady, J. J., Ballou, J. D., & Frankham, R. (2003). The frequency and severity of catastrophic die-offs in vertebrates. Animal conservation, 6, Varian-Ramos, C. W., Karubian, J., Talbott, V., Tapia, I., & Webster, M. S. (2010). Offspring sex ratios reflect lack of repayment by auxiliary males in a cooperatively breeding passerine. Behavioral ecology and sociobiology, 64,

18 The Caribbean : Hotspot of Biodiversity Definitions Biodiversity Hotspots Reid, 1998 Mittermeier et al., 1998 Myers et al.,2000 Rare species Pimm et al., 1995 Reed et al., 2003 Map of the Caribbean. 5th Hotspot of Biodiversity.Extracted from Google Maps 18

19 Peig, J., & Green, A. J. (2009). New perspectives for estimating body condition from mass/length data: the scaled mass index as an alternative method. Oikos, 118, bsma Scaled mass index: M i = M i L 0 L i bsma = bols / r Mi: Body mass of individual i L0: Mean measure of body size Li: Body size of the individual i bols: slope of the ordinary least square regression from log (Mass) against log(size) r: Pearson s correlation coefficient between Body Mass and Body size. 19

20 The White-breasted Thrasher in Martinique : Naturalist accounts Gros-Désormeaux et al. (2014) Gaps in knowledge Demography Sex-ratio (Cooperative breeding) Behavior Distribution of the White-Breasted Thrasher in Martinique - Map 20