Importance of intraspecifically gregarious species in a tropical bird community
In both single- and mixed-species social groups, certain participants are known to play important roles in providing benefits. Identifying these participants is critical for understanding group dynamics, but is often difficult with large roving social groups in the wild. Here, we develop a new approach to characterize roles in social groups and apply it to mixed-species bird flocks (flocks hereafter) in an Indian tropical evergreen forest. Two types of species, namely intraspecifically gregarious and sallying species, are thought to play important roles in flocks because studies have shown they attract other flock participants. However, it is unclear why these types are attractive and whether they are essential for flock formation. We address these questions by focusing on the composition of the subset of flocks containing only two species each. In two-species flocks, it is reasonable to assume that at least one species obtains some kind of benefit. Therefore, only those species combinations that result in benefit to at least one species should occur as two-species flocks. Using data from 540 flocks overall, of which 158 were two-species flocks, we find that intraspecifically gregarious species are disproportionately represented in two-species flocks and always lead flocks when present, and that flocks containing them are joined significantly more by other species. Our results suggest that intraspecifically gregarious species are likely to be the primary benefit providers in flocks and are important for tropical flock formation. Our study also provides a new approach to understanding importance in other mixed-species and single-species social groups.
KeywordsAnimal sociality Facilitation Leadership Mixed-species flocks Species importance
We thank the Ministry of Environment and Forests, Government of India and International Foundation for Science (Grant no. D/4910-1) for supporting this study and the Karnataka forest department for providing permits for field work. We thank Eben Goodale, Rajah Jayapal and Kathryn Sieving for commenting on a draft of this paper. H.S. thanks Prakash, Nagesh, Narayan, Chandrakant and Sadanand for help with fieldwork. This paper was completed when H.S. was a fellow of the Wissenschaftskolleg zu Berlin.
Conflict of interest
The authors declare that they have no conflict of interest.
This study complies with the current laws of India, where the study was carried out.
- Ali S, Ripley SD (1987) Compact handbook of the birds of India and Pakistan, together with those of Bangladesh, Nepal, Bhutan and Sri Lanka, 2nd edn. Oxford University Press, New DelhiGoogle Scholar
- Aureli F, Schaffner CM, Boesch C, Bearder SK, Call J, Chapman CA, Connor R, Di Fiore A, Robin IM, Dunbar S, Henzi P, Holekamp K, Korstjens AH, Layton R, Lee P, Lehmann J, Manson JH, Ramos-Fernandez G, Strier KB, van Schaik CP (2008) Fission-fusion dynamics. Curr Anthropol 49:627–654. doi: 10.1086/667653 CrossRefGoogle Scholar
- Flower T (2010) Fork-tailed drongos use deceptive mimicked alarm calls to steal food. Proc R Soc Lond B. doi: 10.1098/rspb.2010.1932
- Goodale E, Kotagama SW (2005a) Testing the roles of species in mixed-species bird flocks of a Sri Lankan rainforest. J Trop Ecol 21:669–676. doi: 10.1017/S0266467405002609
- Goodale E, Nizam BZ, Robin VV, Sridhar H, Trivedi P, Kotagama SW, Padmalal UKGK, Perera R, Pramod P, Vijayan L (2009) Regional variation in the composition and structure of of mixed-species bird flocks in the Western Ghats and Sri Lanka. Curr Sci 97:648–663Google Scholar
- Greenberg R (2000) Birds of many feathers: the formation and structure of mixed-species flocks of forest birds. In: Boinski S, Gerber PA (eds) On the move: how and why animals travel in groups. University of Chicago Press, Chicago, pp 521–559. doi:http://hdl.handle.net/10088/4394
- Harrison NM, Whitehouse MJ (2011) Mixed-species flocks: an example of niche construction? Anim Behav 81:675–683. doi: 10.1016/j.anbehav.2011.01.013
- Jullien M, Clobert J (2000) The survival value of flocking in neotropical birds: reality or fiction? Ecology 81:3416–3430. doi: 10.1890/0012-9658(2000)081[3416:TSVOFI]2.0.CO;2
- Kéfi S, Berlow EL, Wieters EA, Navarette SA, Petchey OL, Wood SA, Boit A, Joppa LN, Lafferty KD, Williams RJ, Martinez ND, Menge BA, Blanchette CA, Iles AC, Brose U (2012) More than a meal… integrating non-feeding interactions into food webs. Ecol Lett 15:291–300. doi: 10.1111/j.1461-0248.2011.01732.x CrossRefGoogle Scholar
- King DI, Rappole JH (2001) Kleptoparasitism of laughingthrushes Garrulax by Greater racket-tailed drongos Dicrurus paradiseus in Myanmar. Forktail 17:121–122Google Scholar
- Kotagama SW, Goodale E (2004) The composition and spatial organization of mixed-species flocks in a Sri Lankan rainforest. Forktail 20:63–70Google Scholar
- Maldonado-Coelho M, Marini MÂ (2004) Mixed-species bird flocks from Brazilian Atlantic forest: the effects of forest fragmentation and seasonality on their size, richness and stability. Biol Conserv. doi: 10.1016/S0006-3207(03)00169-1
- McLean IG (1984) Feeding association between fantails and saddlebacks: who benefits? NZ J Ecol 7:165–168Google Scholar
- Morse DH (1970) Ecological aspects of some mixed-species foraging flocks of birds. Ecol Monogr 40:119–168. doi: 10.2307/1942443
- Moynihan M (1962) The organization and probable evolution of some mixed-species flocks of Neotropical birds. Smithson Misc Coll 143:1–140Google Scholar
- Remsen JV Jr, Robinson SK (1990) A classification scheme for birds in terrestrial foraging habitats. Stud Avian Biol 13:144–160Google Scholar
- Satischandra SHK, Kudavidanage EP, Kotagama SW, Goodale E (2007) The benefits of joining mixed-species flocks for greater racket-tailed drongos Dicrurus paradiseus. Forktail 23:145–148Google Scholar
- Sazima C, Krajewski JP, Bonaldo RM, Sazima I (2007) Nuclear-follower foraging associations of reef fishes and other animals at an oceanic archipelago. Environ Biol Fish 80:351–361Google Scholar
- Sridhar H, Beauchamp G, Shanker K (2009) Why do birds participate in mixed-species foraging flocks? Anim Behav 78:337–347. doi: 10.1016/j.anbehav.2009.05.008
- Stotz DF (1993) Geographic variation in species composition of mixed species flocks in lowland humid forests in Brazil. Pap Avul Zool 38:61–75Google Scholar
- Stouffer PC, Bierregaard Jr RO (1995) Use of Amazonian forest fragments by understory insectivorous birds. Ecology 76:2429–2445. doi: 10.2307/2265818
- Styring AR, Ickes K (2001) Interactions between the greater racket-tailed drongo and woodpeckers in a lowland Malaysian rainforest. Forktail 17:119–120Google Scholar