Abstract
When a habitat becomes fragmented and surrounded by another habitat this generally causes an increase in predation pressure at habitat transitions, often referred to as an edge effect. Edge effect in the form of enhanced nest predation intensities is one of the most cited explanations for bird population declines in fragmented landscapes. Here, we report results from a nest predation experiment conducted in a tropical montane forest landscape in the Uzungwa Mts., Tanzania. Using artificial nests with chicken eggs, we determined predation rates across a fragmentation gradient. The proportion of indigenous forest in four landscapes used in the study were 0.29, 0.58, 0.75 to 1.0. Nest predation intensities on artificial nests were about 19% higher inside intact forest than at edges in fragmented forest landscapes. Furthermore, predation intensities were relatively constant across a forest fragmentation gradient. Our results thus challenge the applicability and generality of the edge effect, derived from studies almost exclusively conducted in temperate regions rather than tropical forest ecosystems. Nest predation levels differences between tropical montane forest and that reported in other forest ecosystems are discussed.
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References
Andrén H (1992) Corvid density and nest predation in relation to forest fragmentation: a landscape perspective. Ecology 73: 794-804
Andrén H (1995) Effects of landscape composition on predation rates at habitat edges. In: Hansson L,Fharig L andMerriam G (eds) Mosaic Landscapes and Ecological Processes, pp 225-255. Chapman & Hall, London
Andrén H andAngelstam P (1988) Elevated predation rates as an edge effect in habitat islands: experimental evidence. Ecology 66: 1211-1214
Angelstam P (1986) Predation on ground-nesting bird' nest in relation to predator density and habitat edge. Oikos 47: 365-373
Arango-Vélaz N andKattan GH (1997) Effects of forest fragmentation on experimental nest predation in Andean cloud forest. Biological Conservation 81: 137-143
Burkey TV (1993) Edge effects in seed and egg predation at two neotropical rainforest sites. Biological Conservation 66: 139-143
Collar NJ andStuart SN (1988) Key Forest for Threatened Birds in Africa. ICBP Monograph, Cambridge, UK
Gates JE andGysel LW (1978) Avian nest dispersion and fledgling outcome in field-forest edges. Ecology 59: 871-883
Gibbs PE (1991) Avian nestpredation in tropical wet forest: an experimental study. Oikos 60: 155-161
Heywood VH,Mace GM,May RM andStuart SN (1994) Uncertainties in extinction rates. Nature 368: 105
Hoover JP,Brittingham MC andGoodrich JL (1995) Effect of forest patch size on nesting success of wood thrushes. Auk 112: 146-155
Johnsson K (1993) The black woodpecker as a keystone species in forest. Dissertation inWildlife Ecology. Publ. No 24, SLU, Sweden
King DI,DeGraaf RM andGriffin CR (1999) Do predation rates on artificial nests accurately reflect predation rates on natural bird nests? J. Field Orn. 70: 257-262
Kingdon J (1990) Island Africa. Collins, London
Leck CF (1987) Habitat selection in migrant birds: seducive fruits. Trends Ecol. Evol. 2: 33
Martin TE (1987) Artificial nest experiments: effects of nest appearance and type of predators. Condor 89: 925-928
Newmark WD,Manyanza DN,Gamassa DM andSarito HI (1994) The conflict between wildlife and local people living adjacent to protected areas in Tanzania: human density as a predictor. Conservation Biology 8: 249-255
Nour N,Mathyssen E andDhondt AA (1993) Artificial nest predation and habitat fragmentation: different trends in bird and mammal predators. Ecography 16: 111-116
Patton PW (1994) The effects of edge on avian nest success: how strong is the evidence? Conservation Biology 8: 17-26
Rodgers WA (1993) The conservation of the forest resources of East Africa: past influences, present practices and future needs. In: Lovett JC andWasser SK (eds) Biogeography & Ecology of the Rain Forests of Eastern Africa, pp 223-229. Cambridge University Press, Cambridge
Rodgers WA andHomewood KM (1982) Conservation of the Uzungwa Mountains, Tanzania. Biological Conservation 24: 285-304
Roper JJ (1992) Net predation experiments with quail eggs: to much to swallow? Oikos 65: 528-530
Santos T andTelleria JL (1992) Edge effects on nest predation in Mediterranean fragmented forest. Biological Coservation 60: 1-5
Skutch AF (1949) Do tropical birds raise as many young as they can nourish? Ibis 91: 430-455
Small MF andHunter ML (1988) Forest fragmentation and avian nest predation in forested landscapes. Oecologia 76: 62-64
Smith FDM,May RM,Pellew R,Johnson TH andWalters KR (1993) How much do we know about the current extinction rate? Trends Ecol. Evol. 8: 375-378
Stevens SM andHusband TP (1998) The influence of edge on small mammals: evidence from Brazilian Atlantic forest fragments. Biological Conservation 85: 1-8
Stuart SN (1985) Forest birds and their conservation in East Africa. In: Diamond AW andLovejoy TE (eds) Conservation of Tropical Forest Birds, pp 187-197. ICBP, Cambridge, UK
Stuart SN,Jensen FP,Brogge-Jensn S andMiller RJ (1993) The zoogeography of the montane forest avifauna of eastern Tanzania. In: Lovett JC andWasser SK (eds) Biogeography & Ecology of the Rain Forests of Eastern Africa, pp 203-209. Cambridge University Press, Cambridge
Söderström B (1999) Artificial nest predation in tropical and temperate forests: a review. Ecography 22: 455-463
Turner IM (1996) Species loss in fragments of tropical rain forest: a review of the evidence. Journal of Applied Ecology 33: 200-219
Whitcomb RF,Robbins CS,Lynch JF,Whitcomb BL,Klimkiewitcz MK andBystrak D (1981) Effects of forest fragmentation on avifauna in the eastern deciduous forest. In: Burgess RL andSharpe DM (eds) Forest Island Dynamics in Man-Dominated Landscapes, pp 125-205. Springer-Verlag, New York
Whitmore TC andSayer JA (1992) Deforestation and species extinction in tropical moist forest. In: Whitmore TC andSayer JA (eds) Tropical Deforestation and Species Extinction, pp 1-14. Chapman & Hall, London
Wilcove DS (1985) Nest predation in forest tracts and the decline of migratory songbirds. Ecology 66: 1211-1214
Willebrand T,Marcström V (1988) On the danger of using dummy nests to study predation. Auk 105: 378-379
Wong CMT,Sodhi NS andTurner IM (1998) Artificial nest and seed predation experiments in tropical lowland rainforest remnants of Singapore. Biological Conservation 85: 97-104
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Carlson, A., Hartman, G. Tropical forest fragmentation and nest predation – an experimental study in an Eastern Arc montane forest, Tanzania. Biodiversity and Conservation 10, 1077–1085 (2001). https://doi.org/10.1023/A:1016649731062
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DOI: https://doi.org/10.1023/A:1016649731062