Skip to main content
    • Aa
    • Aa

Effects of habitat degradation on mixed-species bird flocks in Indian rain forests

  • Hari Sridhar (a1) and K. Sankar (a1)

Habitat degradation affects mixed-species bird flocks (flock hereafter) through two mechanisms – changes in the bird community from which flocks are drawn and changes in the propensities of species to flock. We determined the relative influence of these two mechanisms by examining variation in flocks across nine rain-forest fragments (range 11–2600 ha) in a plantation landscape in the Western Ghats, India. We found differences between fragments in average number of species (range 10.8–15.2) and individuals (range 19.0–37.6) per flock, number of species that participated in flocks (range 34–59), encounter rates (range 0.5–2.4 flocks h−1) and flock composition. Multiple regression and randomization tests revealed that different mechanisms contributed to this variation. Three flock variables (open-forest individuals per flock, total open-forest species that participated in flocks in a fragment, flock composition) mainly reflected changes in the bird communities of fragments. Habitat structure strongly influenced three flock variables (open-forest species per flock, total and rain-forest individuals per flock) and flock composition to a lesser extent. Finally, flock encounter rate was strongly related to fragment area, but not to abundance of flock participants indicating habitat degradation-induced changes in propensities of species to flock.

Corresponding author
1Corresponding author. Current address: Centre for Ecological Sciences, Indian Institute of Science, Malleswaram, Bangalore – 560012, Karnataka, India. Email:
Linked references
Hide All

This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

F. ACHARD , H. D. EVA , H.-J. STIBIG , P. MAYAUX , J. GALLEGO , T. RICHARDS & J.-P. MALINGREAU 2002. Determination of deforestation rates of the world's humid tropical forests. Science 297:9991002.

C.-C. CHEN & F. HSIEH 2002. Composition and foraging behaviour of mixed-species flocks led by the Grey-cheeked Fulvetta in Fushan Experimental Forest, Taiwan. Ibis 144:313330.

R. J. R. DANIELS , N. V. JOSHI & M. GADGIL 1992. On the relationship between bird and woody plant species diversity in the Uttara Kannada district of south India. Proceedings of the National Academy of Sciences, USA 89:53115315.

D. M. DEBINSKI & R. D. HOLT 2000. A survey and overview of habitat fragmentation experiments. Conservation Biology 14:342355.

P. F. DEVELEY & C. A. PERES 2000. Resource seasonality and the structure of mixed species bird flocks in a coastal Atlantic forest of southeastern Brazil. Journal of Tropical Ecology 16:3353.

A. S. DOLBY & T. C. GRUBB 1998. Benefits to satellite members in mixed-species foraging groups: an experimental analysis. Animal Behaviour 56:501509.

A. S. DOLBY & T. C. GRUBB 1999. Functional roles in mixed-species foraging flocks: a field manipulation. Auk 116:557559.

L. FAHRIG 2003. Effects of habitat fragmentation on biodiversity. Annual Review of Ecology, Evolution and Systematics 34:487515.

G. R. GRAVES & N. J. GOTELLI 1993. Assembly of avian mixed-species flocks in Amazonia. Proceedings of the National Academy of Sciences, USA 90:13881391.

Y. HAILA 2002. A conceptual genealogy of fragmentation research: from island biogeography to landscape ecology. Ecological Applications 12:321334.

P. J. HART & L. A. FREED 2003. Structure and dynamics of mixed-species flocks in a Hawaiian rainforest. The Auk 120:114.

R. HUTTO 1994. The composition and social organization of mixed-species flocks in a tropical deciduous forest in western Mexico. The Condor 96:105118.

M. JULLIEN & J. CLOBERT 2000. The survival value of flocking in neotropical birds: reality or fiction? Ecology 81:34163430

M. JULLIEN & J.-M. THIOLLAY 1998. Multi-species territoriality and dynamics of neotropical understory bird flocks. Journal of Animal Ecology 67:227252.

S. C. LATTA & J. M. WUNDERLE 1996. The composition and foraging ecology of mixed-species flocks in pine forests of Hispaniola. The Condor 98:595607.

T. M. LEE , M. C. K. SOH , N. SODHI , L. P. KOH & S. L. H. LIM 2005. Effects of habitat disturbance on mixed species bird flocks in a tropical sub-montane rainforest. Biological Conservation 122;193204.

M. MALDONADO-COELHO & M. A. MARINI 2000. Effects of forest fragment size and successional stage on mixed-species bird flocks in southeastern Brazil. Condor 102:585594.

M. MALDONADO-COELHO & M. A. MARINI 2004. Mixed-species bird flocks from Brazilian Atlantic forest: the effects of forest fragmentation and seasonality on their size, richness and stability. Biological Conservation 116:1926.

D. H. MORSE 1977. Feeding behavior and predator avoidance in heterospecific groups. Bioscience 27:332339.

C. A. MUNN & J. W. TERBORGH 1979. Multi-species territoriality in neotropical foraging flocks. Condor 81:338347.

N. MYERS , R. A. MITTERMEIER , C. G. MITTERMEIER , G. A. B. DA FONSECA & J. KENT 2000. Biodiversity hotspots for conservation priorities. Nature 403:853858.

G. V. N. POWELL 1989. On the possible contribution of mixed species flocks to species richness in neotropical avifaunas. Behavioral Ecology and Sociobiology 24:387393.

T. R. S. RAMAN 2003. Assessment of census techniques for inter-specific comparisons of tropical rainforest bird densities. Ibis 145:921.

T. R. S. RAMAN , G. S. RAWAT & A. J. T. JOHNSINGH 1998. Recovery of tropical rainforest avifauna in relation to vegetation succession following shifting cultivation in Mizoram, north-east India. Journal of Applied Ecology 35:214231.

P. C. STOUFFER & R. O. BIERREGAARD 1995. Use of Amazonian forest fragments by understory insectivorous birds. Ecology 76:24292445.

J. L. TELLERÍA , E. VIRGÓS , R. CARBONELL , J. PÉREZ-TRIS & T. SANTOS 2001. Behavioural responses to changing landscapes: flock structure and anti-predator strategies of tits wintering in fragmented forests. Oikos 95:253264.

J. W. TERBORGH 1990. Mixed flocks and polyspecific associations: costs and benefits of mixed groups to birds and monkeys. American Journal of Primatology 21:87100.

J. TERBORGH , L. LOPEZ , P. NUÑEZ , M. RAO , G. SHAHABUDDIN , G. ORIHUELA , M. RIVEROS , R. ASCANIO , G. H. ADLER , T. D. LAMBERT & L. BALBAS 2001. Ecological meltdown in predator-free forest fragments. Science 294:19231926.

J.-M. THIOLLAY 1993. Response of a raptor community to shrinking area and degradation of tropical rain forest in the South Western Ghats (India). Ecography 16:97110.

J.-M. THIOLLAY 1997. Disturbance, selective logging and bird diversity: a Neotropical forest study. Biodiversity and Conservation 6:11551173.

J.-M. THIOLLAY 1999a. Responses of an avian community to rainforest degradation. Biodiversity and Conservation 8:513534.

J.-M. THIOLLAY 1999b. Frequency of mixed species flocking in tropical forest birds and correlates of predation risk: an intertropical comparison. Journal of Avian Biology 30:282294.

I. M. TURNER 1996. Species loss in fragments of tropical rainforest: a review of the evidence. Journal of Applied Ecology 33:200209.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Journal of Tropical Ecology
  • ISSN: 0266-4674
  • EISSN: 1469-7831
  • URL: /core/journals/journal-of-tropical-ecology
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 1
Total number of PDF views: 11 *
Loading metrics...

Abstract views

Total abstract views: 122 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 25th May 2017. This data will be updated every 24 hours.