Abstract
Many natural ecosystems in tropical regions are under immense anthropogenic pressure, mostly connected with forest logging. However, several other factors may play important roles. From a conservation perspective, it is important to assess the impacts of these changes in biodiversity hotspots, but adequate data are scarce. We repeated point-count bird monitoring at 29 count-points in an Afromontane ecosystem near Big Babanki in NW Cameroon after a 13-year period. Between the censuses in 2003 and 2016, we found a decrease in bush cover and an increase in herb layer, whereas tree cover did not change. Consequently, we found a decrease in the total number of bird individuals per count-point driven by a decrease in the abundances of shrubland species, mainly nectarivores and granivores (e.g., Northern double-collared sunbird, Black crowned waxbill, Oriole finch, Thick-billed seedeater or Baglafecht weaver). In general, the decrease was found in nectarivore species that depend on flowering bushes (mainly Hypericum spp.). Similarly, we found a decrease in approximately half of the granivore species that often use bush cover for nesting and feeding. Additionally, one large fruit feeding bird, the Great blue turaco, became nearly extinct probably due to hunting activity. The observed contraction of bush cover accompanied by shrubland bird declines possibly results from a decrease in humidity in the area that was indicated by remote sensing. This may be caused by montane forest loss and fragmentation during the second half of the 20th Century. Our findings uncover the long-term consequences of deforestation which are rarely considered, even though they impact key ecosystem functions.
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Data Availability
Data are available in Appendix Table 5.
Code availability
Data were gathered by authors directly in the field.
References
Aleixo A (1999) Effects of selective logging on a bird community in the Brazilian Atlantic forest. Condor 101:537–548
Baselga A, Orme CDL (2012) betapart: an R package for the study of beta diversity. Methods Ecol Evol 3:808–812. https://doi.org/10.1111/j.2041-210X.2012.00224.x
Blake JG, Loiselle BA (2015) Enigmatic declines in bird numbers in lowland forest of eastern Ecuador may be a consequence of climate change. PeerJ 3:e1177. https://doi.org/10.7717/peerj.1177
Borrow N, Demey R (2001) Birds of Western Africa. Christopher Helm, London
Bregman TP, Sekercioglu CH, Tobias JA (2014) Global patterns and predictors of bird species responses to forest fragmentation: Implications for ecosystem function and conservation. Biol Conserv 169:372–383. https://doi.org/10.1016/j.biocon.2013.11.024
Brooks TM, Mittermeier RA, Mittermeier CG, da Fonseca GAB, Rylands AB, Konstant WR, Flick P, Pilgrim J, Oldfield S, Magin G, Hilton-Taylor C (2002) Habitat loss and extinction in the hotspots of biodiversity. Conserv Biol 16:909–923. https://doi.org/10.1046/j.1523-1739.2002.00530.x
Buchhorn M, Smets B, Bertels L, Lesiv M, Tsendbazar N-E, Masiliunas D, Linlin L, Herold M, Fritz S (2020) Copernicus global land service: land cover 100m: collection 3: epoch 2019: Globe (Version V3.0.1)
Canaday Ch (1997) Loss of insectivorous birds along a gradient of human impact in Amazonia. Biol Conserv 77:63–77. https://doi.org/10.1016/0006-3207(95)00115-8
Cheek M, Onana JM, Pollard BJ (2000) The plants of Mount Oku and the Ilim Ridge, Cameroon . Royal Botanic Gardens, Kew
Cheke RA, Mann CF, Allen R (2001) A guide to sunbirds, flowerpeckers, spiderhunters and sugarbirds of the world. Yale University Press, New Haven
Colyn RB, Ehlers Smith DA, Ehlers Smith YC, Smit-Robinson H, Downs CT (2020) Predicted distributions of avian specialists: a framework for conservation of endangered forests under future climates. Divers Distrib 26(6):652–667. https://doi.org/10.1111/ddi.13048
De Coster G, Banks-Leite C, Metzger JP (2015) Atlantic forest bird communities provide different but not fewer functions after habitat loss. Proc Royal Soc B 282(1811):20142844. https://doi.org/10.1098/rspb.2014.2844
DeKlerk HM, Fjeldså J, Blyth S, Burgess ND (2004) Gaps in protected area network for threatened Afrotropical birds. Biol Conserv 117:529–537. https://doi.org/10.1016/j.biocon.2003.09.006
Dell Inc (2016) Dell Statistica (data analysis software system), version 13. software.dell.com
Dornelas M et al (2018) BioTIME: a database of biodiversity time series for the Anthropocene. Glob Ecol Conserv 27:760–786. https://doi.org/10.1111/geb.12729
Dulle HI, Ferger SW, Cordeiro NJ, Howell KM, Schleuning M, Böhning-Gaese K, Hof C (2016) Changes in abundances of forest understorey birds on Africa’s highest mountain subtle effects of climate change. Divers Distrib 22:288–299. https://doi.org/10.1111/ddi.12405
ESRI (2011) ArcGIS desktop: release 10. Environmental Systems Research Institute, Redlands, CA
Fotso RC (2001) A contribution to the ornithology of Mount Oku forest, Cameroon. Malimbus 23:1–12
Fraixedas S, Linden A, Piha M, Cabeza M, Gregory R, Lehikoinen A (2020) A state-of-the-art review on birds as indicators of biodiversity: advances, challenges, and future directions. Ecol Indic 118:106728. https://doi.org/10.1016/j.ecolind.2020.106728
Gill FB, Wolf LL (1975) Economics of feeding territoriality in the golden-winged sunbird. Ecology 56:333–345. https://doi.org/10.2307/1934964
Gibson L, Lynam AJ, Bradshaw CJ, He F, Bickford DP, Woodruff DS, Bumrungsri S, Laurance WF (2013) Near-complete extinction of native small mammal fauna 25 years after forest fragmentation. Science 341(6153):508–1510. https://doi.org/10.1126/science.1240495
Hanski I, Ovaskainen O (2000) The metapopulation capacity of a fragmented landscape. Nature 404(6779):755–758. https://doi.org/10.1038/35008063
Hendershot JN, Smith JR, Anderson CB, Letten AD, Frishkoff LO, Zook JR, Fukami T, Daily GC (2020) Intensive farming drives long-term shifts in avian community composition. Nature 579:393–396. https://doi.org/10.1038/s41586-020-2090-6
Hixon MA, Carpenter FL, Paton DC (1983) Territory area, flower density, and time budgeting in hummingbirds—an experimental and theoretical analysis. Am Nat 122(3):366–391. https://doi.org/10.1086/284141
Hořák D, Sedláček O, Reif J, Riegert J, Pešata M (2009) When savannah encroaches on the forest: tresholds in bird-habitat associations in the Bamenda Highlands, Cameroon. Afr J Ecol 48:822–827. https://doi.org/10.1111/j.1365-2028.2009.01155.x
Janeček Š, Riegert J, Sedláček O, Bartoš M, Hořák D, Reif J, Padyšáková E, Fainová D, Antczak M, Pešata M, Mikeš V, Patáčová E, Altman J, Kantorová J, Hrázský Z, Doležal J (2012) Food selection by avian floral visitors: an important aspect of plant-flower visitor interactions in West Africa. Biol J Linn Soc 107:355–367. https://doi.org/10.1111/j.1095-8312.2012.01943.x
Jankowski JE, Merkord ChL, Rios WF, Cabrera KG, Revilla NS, Silman MR (2013) The relationship of tropical bird communities to tree species composition and vegetation structure along an Andean elevational gradient. J Biogeogr 40:950–962. https://doi.org/10.2307/23463612
Joly CA, Metzger JP, Tabarelli M (2014) Experiences from the Brazilian Atlantic Forest: ecological findings and conservation initiatives. New Phytol 204(3):459–473. https://doi.org/10.1111/nph.12989
Kennedy CM, Oakleaf JR, Theobald DM, Baruch-Mordo S, Kiesecker J (2019) Managing the middle: a shift in conservation priorities based on the global human modification gradient. Glob Change Biol 25(3):811–826. https://doi.org/10.1111/gcb.14549
Kennedy CM, Oakleaf JR, Theobald DM, Baruch-Mordo S, Kiesecker J (2020) Global human modification of terrestrial systems. Palisades, NY: NASA Socioeconomic Data and Applications Center (SEDAC). https://doi.org/10.7927/edbc-3z60
Koh LP (2008) Can oil palm plantations be made more hospitable for forest butterflies and birds? J Appl Ecol 45:1002–1009. https://doi.org/10.1111/j.1365-2664.2008.01491.x
Korfanta NM, Newmark WD, Kauffman MJ (2012) Long-term demographic consequences of habitat fragmentation to a tropical understory bird community. Ecology 93(12):2548–2559. https://doi.org/10.2307/41739613
LaManna JA, Martin TE (2016) Logging impacts on avian species richness and composition differ across latitudes and foraging and breeding habitat preferences. Biol Rev 92(3):1657–1674. https://doi.org/10.1111/brv.12300
Languy M (2019) The birds of Cameroon. Their status and distribution. Series ’Studies in Afrotropical Zoology´ 299. Royal Museum for Central Africa, Tervuren
Latja P, Valtonen A, Mallinga GM, Roininen H (2016) Active restoration facilitates bird community recovery in an Afrotropical rainforest. Biol Conserv 200:70–79. https://doi.org/10.1016/j.biocon.2016.05.035
Laurance WF, Camargo JLC, Luizao RCC, Laurance SG, Pimm SL, Bruna EM, Stouffer PC, Williamson GB, Benitez-Malvido J, Vasconcelos HL, Van Houtan KS, Zartman CE, Boyle SA, Didham RK, Andrade A, Lovejoy TE (2011) The fate of Amazonian forest fragments: a 32-year investigation. Biol Conserv 144:56–67. https://doi.org/10.1016/j.biocon.2010.09.021
Leaver J, Mulvaney J, Ehlers Smith DA, Ehlers Smith YC, Cherry MI (2019) Response of bird functional diversity to forest product harvesting in the Eastern Cape, South Africa. For Ecol Manag 445:82–95. https://doi.org/10.1016/j.foreco.2019.04.054
Legendre P, Legendre L (2012) Numerical ecology, 3rd edn. Elsevier, Amsterdam
Loiselle BA, Blake JG (1994) Annual variation in birds and plants of a tropical second-growth woodlands. Condor 96:368–380. https://doi.org/10.2307/1369321
Magurran AE, Baillie SR, Buckland ST, Dick JM, Elston DA, Scott EM, Smith RI, Somerfield PJ, Watt AD (2010) Long-term datasets in biodiversity research and monitoring: assessing change in ecological communities through time. Trends Ecol Evol 25(10):574–582. https://doi.org/10.1016/j.tree.2010.06.016
Marrot P, Garant D, Charmantier A (2015) Spatial autocorrelation in fitness affects the estimation of natural selection in the wild. Methods Ecol Evol 6:1474–1483. https://doi.org/10.1111/2041-210X.12448
Mbue IN, Ge J (2010) Landscape change in the Bamenda Highlands of Northwestern Cameroon: Modeling the driving forces of smallholder deforestation. The 2nd conference on environmental science and information application technology, Wuhan 2010:813–816
Myers N, Mittermeier RA, Mittermeier CG, da Fonseca GAB, Kent J (2000) Biodiversity hotspots for conservation priorities. Nature 403:853–858. https://doi.org/10.1038/35002501
Newbold T, Scharlemann JPW, Butchart SHM, Şekercioğlu ÇH, Alkemade R, Booth H, Purves DW (2012) Ecological traits affect the response of tropical forest bird species to land-use intensity. Proc Royal Soc B 280:20122131. https://doi.org/10.1098/rspb.2012.2131
Orme CDL, Davies RG, Burgess M, Eigenbrod F, Pickup N, Olson VA, Webster AJ, Ding TS, Rasmussen PC, Stattersfield AJ, Bennet PM, Blackburn TM, Gaston KJ, Owens IPF (2005) Global hotspots of species richness are not congruent with endemism of threat. Nature 436:1016–1019. https://doi.org/10.1038/nature03850
Osuri AM, Mendiratta U, Naniwadekar R, Varma V, Naeemn S (2020) Hunting and forest modification have distinct defaunation impacts on tropical mammals and birds. Front for Glob Change 2:87. https://doi.org/10.3389/ffgc.2019.00087
Peres CA (2001) Synergistic effects of subsistence hunting and habitat fragmentation on Amazonian forest vertebrates. Conserv Biol 15(6):1490–1505. https://doi.org/10.1046/j.1523-1739.2001.01089.x
Pimm SL, Jenkins CN, Abell R, Brooks TM, Gittleman JL, Joppa LN, Raven PH, Roberts CM, Sexton JO (2014) The biodiversity of species and their rates of extinction, distribution, and protection. Science 344:1246752. https://doi.org/10.1126/science.1246752
R Core Team (2020) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/
Reif J, Hořák D, Sedláček O, Riegert J, Pešata M, Hrázský Z, Janeček Š, Storch D (2006) Unusual abundance-range size relationship in an Afromontane bird community: the effect of geographic isolation? J Biogeogr 33:1959–1968. https://doi.org/10.1111/j.1365-2699.2006.01547.x
Reif J, Sedláček O, Hořák D, Riegert J, Pešata M, Hrázský Z, Janeček Š (2007) Habitat preferences of birds in a montane forest mosaic in the Bamenda Highlands. Cameroon Ostrich 78(1):31–36. https://doi.org/10.2989/OSTRICH.2007.78.1.5.4
Rueda-Hernandez R, MacGregor-Fors I, Renton K (2015) Shifts in resident bird communities associated with cloud forest patch size in Central Veracruz. Mexico Avian Conserv Ecol 10(2):2. https://doi.org/10.5751/ACE-00751-100202
Ruiz-Gutiérrez V, Zipkin EF, Dhondt AA (2010) Occupancy dynamics in a tropical bird community: unexpectedly high forest use by birds classified as non-forest species. J Appl Ecol 47:621–630. https://doi.org/10.1111/j.1365-2664.2010.01811.x
Sedláček O, Hořák D, Riegert J, Reif J, Pešata M (2004) Notes to the occurrence of Palearctic migrants in Cameroon. Sylvia 40:63–78
Sedláček O, Reif J, Hořák D, Riegert J, Pešata M, Klvaňa P (2007) The birds of a montane forest mosaic in Big Babanki area, Bamenda Highlands, Cameroon. Malimbus 29:89–100. https://doi.org/10.2989/OSTRICH.2007.78.1.5.49
Şekercioğlu ÇH, Mendenhall CD, Oviedo-Brenes F, Horns JJ, Ehrlich PR, Daily GC (2019) Long-term declines in bird populations in tropical agricultural countryside. PNAS 116(20):9903–9912. https://doi.org/10.1073/pnas.1802732116
Shankar Raman TR, Rawat GS, Johnsingh JT (1998) Recovery of tropical rainforest avifauna in relation to vegetation succession following shifting cultivation in Mizoram, India. J Appl Ecol 35:214–231. https://doi.org/10.1046/j.1365-2664.1998.00297.x
Shannon CE (1948) A mathematical theory of communication. Bell Syst Tech J 27:379–423, 623–656
Šmilauer P, Lepš J (2014) Multivariate analysis of ecological data using Canoco 5, 2nd edn. Cambridge University Press, Cambridge
Sodhi NS, Posa MRC, Lee TM, Warkentin IG (2008) Effects of disturbance or loss of tropical rainforest on birds. Auk 125(3):511–519. https://doi.org/10.1525/auk.2008.1708
Stattersfield AJ, Crosby MJ, Long AJ, Wege DC (1998) Endemic bird areas of the world. Birdlife International, Cambridge
Stuart SN (ed) (1986) Conservation of Cameroon montane forests. International Council for Bird Preservation, Cambridge
ter Braak C, Šmilauer P (2012) Canoco reference manual and user’s guide: software for ordination, version 5.0. Microcomputer Power, Ithaca
Thiollay J-M (1999) Responses of an avian community to rain forest degradation. Biodivers Conserv 8:513–534. https://doi.org/10.1023/A:1008912416587
Tilker A, Abrams JF, Mohamed A, Nguyen A, Wong ST, Sollman R, Niedballa J, Bhagwat T, Gray TNE, Rawson BM, Guegan F, Kissing J, Wegmann M, Wilting A (2019) Habitat degradation and discriminate hunting differentially impact faunal communities in the Southeast Asian tropical biodiversity hotspot. Commun Biol 2:396. https://doi.org/10.1038/s42003-019-0640-y
Tvardíková K (2010) Bird abundances in primary and secondary growth in Papua New Guinea: a preliminary assessment. Trop Conserv Sci 3:373–388. https://doi.org/10.1177/194008291000300403
Vidal MM, Banks-Leite C, Tambosi LR, Hasui E, Develey PF, Silva WR, Guimaraes PR Jr, Metzger JP (2019) Predicting the non-linear collapse of plant-frugivore networks due to habitat loss. Ecography 42:1765–1776. https://doi.org/10.1111/ecog.04403
Waltert M, Bobo KS, Sainge NM, Fermon H, Mühlenberg M (2005) From forest to farmland: Habitat effects on Afrotropical forest bird diversity. Ecol Appl 15(4):1351–1366. https://doi.org/10.1890/04-1002
Winfree R, Fox JW, Williams NM, Reilly JR, Cariveau DP (2015) Abundance of common species, not species richness, drives delivery of a real-world ecosystem service. Ecol Lett 18:626–635. https://doi.org/10.1111/ele.12424
Woog F, Ramanitra N, Adrianarivelosoa SR (2006) Effects of deforestation on eastern Malagasy bird communities. In: Schwitzer C et al (eds) Proceedings of the German-Malagasy Research Cooperation in Life and Earth Sciences, pp 203–214
Zhang H, Chang J, Zhang L, Wang Y, Li Y, Wang X (2018) NDVI dynamic changes and their relationship with meteorological factors and soil moisture. Environ Earth Sci 77:482. https://doi.org/10.1007/s12665-018-7759-x
Acknowledgements
We thank to Ernest Vunan Amohlon and the entire Big Babanki community for their kind help during our visits to Cameroon. The research was founded by Czech Science Foundation (GACR 21-17125S).
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The research was founded by Czech Science Foundation (GACR 21-17125S).
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JRi, ZH, OS, JRe and DH collected field data in the year 2003. In the year 2016, data were collected by JRi, JV and KC. Data were analyzed by JRi and SG. JRi wrote the manuscript with key inputs from DH, JRe and comments of other authors.
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Riegert, J., Chmel, K., Vlček, J. et al. Alarming declines in bird abundance in an Afromontane global biodiversity hotspot. Biodivers Conserv 30, 3385–3408 (2021). https://doi.org/10.1007/s10531-021-02252-1
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DOI: https://doi.org/10.1007/s10531-021-02252-1