Article

Article name POPULATION, NESTING CHARACTERISTICS, AND BREEDING ECOLOGY OF THE CRITICALLY ENDANGERED GYPS INDICUS IN MUDUMALAI TIGER RESERVE, SOUTH INDIA
Authors

Arockianathan Samson, PhD, Centre Manager, Bombay Natural History Society, Vulture Conservation Programme, Vulture Conservation Breeding Centre (Bhopal, 462 044, Madhya Pradesh, India); iD ORCID: https://orcid.org/0000-0002-0804-7941; e-mail: kingvulture1786@gmail.com
Jabamalainathan L. Princy, PhD, Department of Zoology and Wildlife Biology, Government Arts College (Udhagamandalam, 643 002, Nilgiris, Tamil Nadu, India); iD ORCID: https://orcid.org/0000-0001-8884-9006
Balasundaram Ramakrishnan, PhD, Associate Professor, Department of Wildlife Biology, Government Arts College (Udhagamandalam, 643 002, Nilgiris, Tamil Nadu, India); iD ORCID: https://orcid.org/0000-0003-0698-1383; e-mail: ramkiwildlife2011@gmail.com

Reference to article

Samson A., Princy J.L., Ramakrishnan B. 2024. Population, nesting characteristics, and breeding ecology of the critically endangered Gyps indicus in Mudumalai Tiger Reserve, South India. Nature Conservation Research 9(4). https://dx.doi.org/10.24189/ncr.2024.027

Section Research articles
DOI https://dx.doi.org/10.24189/ncr.2024.027
Abstract

The species extinction rate has recently accelerated worldwide and is a thousand times higher than through natural processes alone. Small, isolated populations are especially vulnerable to extinction due to deterministic and stochastic threats. Hence, the conservation of such populations is challenging. The present study from 2015 to 2021 aimed to understand the population, nesting characteristics, and breeding ecology of the country's southernmost population of Gyps indicus in Mudumalai Tiger Reserve, South India. The population estimation was performed on the roosting and nesting sites of Gyps indicus in the Mudumalai Tiger Reserve. To study the nesting characteristics and breeding ecology, each nesting colony was systematically visited four times per month during the breeding season (October to May). Assessments of threats were estimated during the field visits. In 2015–2021, four breeding sites were identified. Two nesting sites were identified in 2016 and two more in 2017 and 2020. The mean altitude of the nesting sites was 1122.25 ± 170.06 m a.s.l., ranging from 821 m a.s.l. to 1600 m a.s.l. In the Protected Area, two nests were located on east-facing exposure, one nest on southeast-facing exposure, and one nest on south-facing exposure. In terms of population composition, the mean number of adult individuals steadily increased from 9.5 ± 0.46 in 2016 to 14.08 ± 0.67 in 2021. Consequently, the mean total number of individuals per colony increased from 13.66 ± 0.56 in 2016 to 27.83 ± 0.62 in 2021. A total of 40 (in average, 6.66 ± 0.49 pairs/year) territorial pairs with occupied nests were observed in 2015–2021. Of them, 31 (in average, 5.16 ± 0.30 pairs/year) breeding pairs had laid eggs. Successful incubation was recorded, and the mean incubation period was 63.64 ± 1.74 days. Out of 31 incubated nests, 23 fledglings (3.83 ± 0.47 individuals/year) successfully came out with 74% breeding success. The entire nesting period was 128.43 ± 1.16 days. In total, out of 17 failed breeding attempts nine (53%) were detected before egg laying, and eight (47%) were found during incubation. There were no significant differences between nests abandoned before and after egg laying (t = 0.4152, p > 0.05). During the breeding seasons of 2015–2017, a human-made forest fire posed a serious threat to nesting colonies of Gyps indicus, resulting in no observed nesting. A species-specific conservation-oriented action programme is necessary to secure this last southernmost wild viable Gyps indicus population in the Mudumalai Tiger Reserve. At this juncture, we highly recommend declaring the buffer zone of the Mudumalai Tiger Reserve as a «Vulture Sanctuary» to provide a legal protection of the Gyps indicus population living in the studied area.

Keywords

cliffs, colony, egg, fledgling, incubation, roosting, vulture

Artice information

Received: 23.02.2023. Revised: 27.08.2024. Accepted: 24.09.2024.

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References

Acharya R., Cuthbert R., Baral H.S., Shah K.B. 2009. Rapid population declines of Himalayan Griffon Gyps himalayensis in Upper Mustang, Nepal. Bird Conservation International 19(1): 99–107. DOI: 10.1017/S0959270908007417
Altmann J. 1974. Observational study of behavior: Sampling methods. Behaviour 49(3–4): 227–266. DOI: 10.1163/156853974X00534
Andalus. 1993. Boletín Monográfico Buitre Negro. Sevilla: Andalus.
Anderson H.B., Madsen J., Fuglei E., Jensen G.H., Woodin S.J., van der Wal R. 2015. The dilemma of where to nest: influence of spring snow cover, food proximity and predator abundance on reproductive success of an arctic-breeding migratory herbivore is dependent on nesting habitat choice. Polar Biology 38(2): 153–162. DOI: 10.1007/s00300-014-1574-y
Baral N., Gautam R., Tamang B. 2005. Population status and breeding ecology of White-rumped Vulture Gyps bengalensis in Rampur Valley, Nepal. Forktail 21: 87–91.
Barbosa A., Moreno J., Potti J., Merino S. 1997. Breeding group size, nest position and breeding success in the chinstrap penguin. Polar Biology 18(6): 410–414. DOI: 10.1007/s003000050207
Bevers M., Flather C.H. 1999. The distribution and abundance of populations limited at multiple spatial scales. Journal of Animal Ecology 68(5): 976–987. DOI: 10.1046/j.1365-2656.1999.00345.x
BirdLife International. 2021. Gyps indicus. In: The IUCN Red List of Threatened Species 2021: e.T22729731A204672586. Available from https://dx.doi.org/10.2305/IUCN.UK.2021-3.RLTS.T22729731A204672586.en
Boshoff A.F., Minnie J.C., Tambling C.J., Michael M.D. 2011. The impact of power line-related mortality on the Cape Vulture Gyps coprotheres in a part of its range, with an emphasis on electrocution. Bird Conservation International 21(3): 311–327. DOI: 10.1017/S095927091100013X
Boyce M.S. 1992. Population viability analysis. Annual Review of Ecology and Systematics 23: 481–506.
Bridgeford P., Bridgeford M. 2003. Ten years of monitoring breeding Lappet-faced Vultures Torgos tracheliotos in the Namib-Naukluft Park, Namibia. Vulture News 48: 3–11.
Brunton D.H. 1997. Impacts of predators: center nests are less successful than edge nests in a large colony of Least Terns. Condor 99(2): 372–380. DOI: 10.2307/1369943
Brunton D. 1999. “Optimal" Colony Size for Least Terns: An Inter-Colony Study of Opposing Selective Pressures by Predators. Condor 101(3): 607–615. DOI: 10.2307/1370190
Buechley E.R., Şekercioğlu C.H. 2016. The avian scavenger crisis: Looming extinctions, trophic cascades, and loss of critical ecosystem functions. Biological Conservation 198: 220–228. DOI: 10.1016/j.biocon.2016.04.001
Buechley E.R., Santangeli A., Girardello M., Neate-Clegg M.H., Oleyar D., McClure C.J.W., Şekercioğlu C.H. 2019. Global raptor research and conservation priorities: tropical raptors fall prey to knowledge gaps. Diversity and Distributions 25(6): 856–869. DOI: 10.1111/ddi.12901
Camiña A., Yosef R. 2012. Effect of European Union BSE-Related Enactments on Fledgling Eurasian Griffons Gyps fulvus. Acta Ornithologica 47(2): 101–109. DOI: 10.3161/000164512X662205
Carrete M., Sánchez-Zapata J.A., Benítez J.R., Lobón M., Montoya F., Donázar J.A. 2012. Mortality at wind-farms is positively related to large-scale distribution and aggregation in griffon vultures. Biological Conservation 145(1): 102–108. DOI: 10.1016/j.biocon.2011.10.017
Carlon J. 1992. Breeding phenology of the Egyptian vulture, World Working Group on Birds of Prey and Owls. Newsletter 16/17: 12–13.
Champion H.G., Seth S.K. 1968. A Revised Survey of Forest Types of India. New Delhi: Government of India. 404 p.
Chhangani A.K. 2004. Status of a breeding population of Long-billed Vultures Gyps indicus indicus in and around Jodhpur (Rajasthan), India. Vulture News 50: 15–22.
Chishty N., Choudhary N.L. 2020. Successful Breeding Rate and Population Status of Indian Vulture (Gyps indicus) at Kailashpuri, Udaipur District, Rajasthan. Environment and Ecology 38(4): 929–936.
Collar N., Chen H., Crosby M. 2001. Threatened Birds of Asia: The BirdLife International Red Data Book. Cambridge: Birdlife International. 34 p.
Dobrev D., Arkumarev V., Dobrev V., Stamenov A., Demerdzhiev D. 2020. Use and selection of roost sites by Eurasian Griffon Vultures Gyps fulvus in Bulgaria. Bird Study 67(4): 496–504. DOI: 10.1080/00063657.2021.1950122
Fernández C., Azkona P., Donázar J.A. 1998. Density-dependent effects on productivity in the Griffon Vulture Gyps fulvus: the role of interference and habitat heterogeneity. Ibis 140(1): 64–69. DOI: 10.1111/j.1474-919X.1998.tb04542.x
Fergusons-Lees J., Christie D.A. 2001. Raptors of the World. London: Houghton Mifflin Harcourt. 992 p.
Ghimire B. 2016. Breeding status of White-rumped Vulture Gyps bengalensis in Rupandehi District, Nepal. MSc Thesis. Kirtipur, Nepal: Tribhuvan University. 63 p.
Gilbert M., Watson R.T., Virani M.Z., Oaks J.L., Ahmed S., Chaudhry M.J.I., Arshad M., Mahmood S., Ali A., Khan A.A. 2006. Rapid population declines and mortality clusters in three Oriental White-backed Vulture Gyps bengalensis colonies in Pakistan due to diclofenac poisoning. Oryx 40(4): 388–399. DOI: 10.1017/S0030605306001347
Giraldeau L.A., Gillis D. 1985. Optimal group size can be stable: a reply to Sibly. Animal Behaviour 33(2): 666–667. DOI: 10.1016/s0003-3472(85)80091-9
Green R.E., Newton I., Shultz S., Cunningham A.A., Gilbert M., Pain D.J., Prakash V. 2004. Diclofenac poisoning as a cause of vulture population declines across the Indian subcontinent. Journal of Applied Ecology 41(5): 793–800. DOI: 10.1111/j.0021-8901.2004.00954.x
Gurjar R.L., Gawande P.J. 2011. A note on the vulture population in Panna Tiger Reserve, Central India. Podoces 6(1): 83–86.
Haynes T.B., Schmutz J.A., Lindberg M.S., Wright K.G., Uher-Koch B.D., Rosenberger A.E. 2014. Occupancy of Yellow-billed and Pacific loons: Evidence for interspecific competition and habitat mediated co-occurrence. Journal of Avian Biology 45(3): 296–304. DOI: 10.1111/jav.00394
Hernández M., Margalida A. 2008. Pesticide abuse in Europe: Effects on the Cinereous vulture (Aegypius monachus) population in Spain. Ecotoxicology 17(4): 264–272. DOI: 10.1007/s10646-008-0193-1
Hernández M., Margalida A. 2009. Poison-related mortality effects in the endangered Egyptian vulture (Neophron percnopterus) population in Spain. European Journal of Wildlife Research 55(4): 415–423. DOI: 10.1007/s10344-009-0255-6
Henriques M., Granadeiro J.P., Monteiro H., Nuno A., Lecoq M., Cardoso P., Regalla A., Catry P. 2018. Not in wilderness: African vulture strongholds remain in areas with high human density. PLoS ONE 13(1): e0190594. DOI: 10.1371/journal.pone.0190594
Hunt G.L., Eppley Z.A., Schneider D.C. 1986. Reproductive performance of seabirds: the importance of population and colony size. Auk 103(2): 306–317. DOI: 10.1093/auk/103.2.306
Jha K.K., Jha R., Campbell M.O. 2021. The Distribution, Nesting Habits and Status of Threatened Vulture Species in Protected Areas of Central India. Ecological Questions 32(3): 7–22. DOI: 10.12775/EQ.2021.020
Kramer D.L. 1985. Are colonies supraoptimal groups?. Animal Behaviour 33(3): 1031–1032. DOI: 10.1016/S0003-3472(85)80041-5
Kudo T., Ozaki K., Takao G., Sakai T., Yonekawa H., Ikeda K. 2005. Landscape analysis of northern goshawk breeding home range in northern Japan. Journal of Wildlife Management 69(3): 1229–1239. DOI: 10.2193/0022-541X(2005)069[1229:LAONGB]2.0.CO;2
Kulshreshtha M. 2001. Long-billed Vulture Gyps indicus nesting on trees in the Thar Desert, Rajasthan. Journal of the Bombay Natural History Society 983: 446–450.
Kushwaha S., Kanaujia A. 2009. Study on present status of vulture (Gyps spp.) fauna in some regions of Bundelkhand, India. Research in Environment and Life Sciences 2(1): 7–10.
Liberatori F., Penteriani V. 2001. A long-term analysis of the declining population of the Egyptian vulture in the Italian peninsula: distribution, habitat preference, productivity and conservation implications. Biological Conservation 101(3): 381–389. DOI: 10.1016/S0006-3207(01)00086-6
Mainwaring M.C., Deeming D.C., Jones C.I., Hartley I.R. 2014. Adaptive latitudinal variation in Common Blackbird Turdus merula nest characteristics. Ecology and Evolution 4(6): 851–861. DOI: 10.1002/ece3.952
Mallory M.L., Forbes M.R. 2011. Nest shelter predicts nesting success but not nesting phenology or parental behaviors in High Arctic Northern Fulmars Fulmarus glacialis. Journal of Ornithology 152(1): 119–126. DOI: 10.1007/s10336-010-0556-2
Margalida A., Colomer M.À. 2012. Modelling the effects of sanitary policies on European vulture conservation. Scientific Reports 2: 753. DOI: 10.1038/srep00753
Margalida A., Donázar J.A., Carrete M., Sánchez-Zapata J.A. 2010. Sanitary versus environmental policies: Fitting together two pieces of the puzzle of European vulture conservation. Journal of Applied Ecology 47(4): 931–935. DOI: 10.1111/j.1365-2664.2010.01835.x
Margalida A., Bogliani G., Bowden C.G.R., Donázar J.A., Genero F., Gilbert M., Karesh W.B., Kock R., Lubroth J., Manteca X., Naidoo V., Neimanis A., Sánchez-Zapata J.A., Taggart M.A., Vaarten J., Yon L., Kuiken T., Green R.E. 2014. One Health approach to use of veterinary pharmaceuticals. Science 346(6215): 1296–1298. DOI: 10.1126/science.1260260
Margalida A., Ogada D. 2018. Old world vultures in a changing environment. In: J.H. Sarasola, J.M. Grande, J.J. Negro (Eds.): Birds of Prey. Springer, Cham. P. 457–471. DOI: 10.1007/978-3-319-73745-4_19
Martin T.E. 1993. Nest predation and nest sites: new perspectives on old patterns. Bioscience 43(8): 523–532. DOI: 10.2307/1311947
Marinković S.P., Orlandić L.B., Skorić S.B., Karadžić B.D. 2012. Nest-Site Preference of Griffon Vulture (Gyps fulvus) in Herzegovina. Archives of Biological Science 64(1): 385–392. DOI: 10.2298/ABS1201385M
McClure C.J.W., Rolek B.W., Virani M.Z. 2021. Contrasting Trends in Abundance of Indian Vultures (Gyps indicus) Between Two Study Sites in Neighboring Indian States. Frontiers in Ecology and Evolution 9: 629482. DOI: 10.3389/fevo.2021.629482
Mihoub J.B., Jiguet F., Lécuyer P., Eliotout B., Sarrazin F. 2013. Modelling nesting site suitability in a population of reintroduced Eurasian black vultures Aegypius monachus in the Grands Causses, France. Oryx 48(1): 116–124. DOI: 10.1017/S0030605312000634
Misher C., Bajpai H., Bhattarai S., Sharma P., Sharma R., Kumar N. 2017. Observations on the breeding of Indian long-billed vultures Gyps indicus at Gapernath, Chambal River in Rajasthan, India. Vulture News 72: 14–21.
Monadjem A. 2001. Observations on the African white-backed vulture Gyps africanus nesting at Mlawula Nature Reserve, Swaziland. Vulture News 45: 3–10.
Monadjem A., Garcelon D.K. 2005. Nesting distribution of vultures in relation to land use in Swaziland. Biodiversity and Conservation 14(9): 2079–2093. DOI: 10.1007/s10531-004-4358-9
Morán-López R., Sánchez Guzmán J.M., Borrego E.C., Sánchez A.V. 2006. Nest-site selection of endangered cinereous vulture (Aegypius monachus) populations affected by anthropogenic disturbance: Present and future conservation implications. Animal Conservation 9(1): 29–37. DOI: 10.1111/j.1469-1795.2005.00003.x
Mundy P.J., Butchart D., Ledger J., Piper S. 1992. The vultures of Africa. London: Academic Press. 460 p.
Naoroji R.K. 2007. Birds of prey of the Indian subcontinent. New Delhi: Om Books International. 692 p.
Newton I. 1979. Population Ecology of Raptors. Vermillion: Buteo Books. 399 p.
Oaks J.L., Gilbert M., Virani M.Z., Watson R.T., Meteyer C.U., Rideout B.A., Shivaprasad H.L., Ahmed S., Chaudhry M.J.I., Arshad M., Mahmood S., Ali A., Khan A.A. 2004. Diclofenac residues as the cause of vulture population decline in Pakistan. Nature 427(6975): 630–633. DOI: 10.1038/nature02317
Ogada D.L., Keesing F., Virani M.Z. 2012. Dropping dead: causes and consequences of vulture population declines worldwide. Annals of the New York Academy of Sciences 1249(1): 57–71. DOI: 10.1111/j.1749-6632.2011.06293.x
Oro D., Margalida A., Carrete M., Heredia R., Donázar J.A. 2008. Testing the goodness of supplementary feeding to enhance population viability in an endangered vulture. PLoS ONE 3(12): e4084. DOI: 10.1371/journal.pone.0004084
Padma A. 2018. Population, breeding ecology and conservation threats of Long-billed vultures (Gyps indicus) in the Ramadevarabetta Vulture Sanctuary (RVS) in Ramanagara Hills, Karnataka. In: B. Ramakrishnan (Eds.): Proceedings of the workshop on “Securing Vulture Population in Southern India (SVPSI 2018). Udhagamandalam, Tamil Nadu, India. P. 63–68.
Pain D.J., Bowden C.G.R., Cunningham A.A., Cuthbert R., Das D., Gilbert M., Jakati R.D., Jhala Y., Khan A.A., Naidoo V., Lindsay O.J., Parry-Jones J., Prakash V., Rahmani A., Ranade S.P., Baral H.S., Senacha K.R., Saravanan S., Shah N., Swan G., Swarup D., Taggart M.A., Watson R.T., Virani M.Z., Wolter K., Green R.E. 2008. The race to prevent the extinction of South Asian vultures. Bird Conservation International 18: S30–S48. DOI: 10.1017/s0959270908000324
Postupalsky S. 1974. Raptor reproductive success: some problems with methods, criteria, and terminology. In: F.N. Hamestrom, B.E. Harrell, R.R. Olendorff (Eds.): Proceedings of the conference on raptor conservation techniques. Fort Collins, Colorado, USA. P. 21–31.
Prakash V. 1999. Status of vultures in Keoladeo National Park, Bharatpur, Rajasthan, with special reference to population crash in Gyps species. Journal of the Bombay Natural History Society 96: 365–378.
Prakash V., Pain D.J., Cunningham A.A., Donald P.F., Prakash N., Verma A., Gargi R., Sivakumar S., Rahmani A.R. 2003. Catastrophic collapse of Indian white-backed Gyps bengalensis and long-billed Gyps indicus vulture populations. Biological Conservation 109(3): 381–390. DOI: 10.1016/S0006-3207(02)00164-7
Prakash V., Green R.E., Pain D.J., Ranade S.P., Saravanan S., Prakash N., Venkitachalam R., Cuthbert R., Rahmani A.R., Cunningham A.A. 2007. Recent changes in populations of resident Gyps vultures in India. Journal of the Bombay Natural History Society 104(2): 129–135.
Prakash V., Bishwakarma M.C., Chaudhary A., Cuthbert R., Dave R., Kulkarni M., Kumar S., Paudel K., Ranade S., Shringarpure R., Green R.E. 2012. The population decline of Gyps vultures in India and Nepal has slowed since veterinary use of diclofenac was banned. PLoS ONE 7(11): e49118. DOI: 10.1371/journal.pone.0049118
Prakash V., Galligan T.H., Chakraborty S.S., Dave R., Kulkarni M.D., Prakash N., Shringarpure R.N., Ranade S.P., Green R.E. 2019. Recent changes in populations of Critically Endangered Gyps vultures in India. Bird Conservation International 29(1): 55–70. DOI: 10.1017/S0959270917000545
Rabenold P.P. 1987. Recruitment to food in Black Vultures: evidence for following from communal roosts. Animal Behavior 35(6): 1775–1785. DOI: 10.1016/S0003-3472(87)80070-2
Ramakrishnan B., Kannan G., Samson A., Ramkumar K., Ramasubramanian S. 2014. Nesting of White-rumped Vulture (Gyps bengalensis) in the Segur Plateau of the Nilgiri North forest Division, Tamilnadu, India. Indian Forester 140(10): 1014–1018. DOI: 10.36808/if/2014/v140i10/53493
Rasmussen P.C., Anderton J.C. 2005. Birds of South Asia: the Ripley guide. 1st ed. 2 volumes. Washington, D.C.; Barcelona: Smithsonian Institution and Lynx Editions. P. 1–378.
Ravikanth M., Baskaran N. 2023. Breeding ecology of critically endangered Long-billed vulture Gyps indicus (Scopoli, 1786) and White-rumped vulture G. bengalensis (Gmelin, 1788) in Kaghaznagar Forest Division and its adjoining areas in the Deccan Plateau, India. Journal of Animal Diversity 5(3): 31–42. DOI: 10.61186/JAD.2023.5.3.4
Ravikanth M., Ram Mohan M. 2016. Breeding Biology of Critically Endangered Long-billed Vulture (Gyps indicus) at a Unique Site in Telangana State, India. Ambient Science 3(1): 49–51. DOI: 10.21276/ambi.2016.03.1.nn01
Rodriguez-Lado L., Tapia L. 2012. Suitable breeding habitat for golden eagle (Aquila chrysaëtos) in a border of distribution area in northwestern Spain: advantages of using remote sensing information vs. land use maps. Vie et Milieu 62(2): 77–85.
Sæther B.E., Bakke Ø. 2000. Avian life history variation and contribution of demographic traits to the population growth rate. Ecology 81(3): 642–653. DOI: 10.1890/0012-9658(2000)081[0642:ALHVAC]2.0.CO;2
Samson A., Ramakrishnan B. 2016. Observation of a population of Egyptian Vultures Neophron percnopterus in Ramanagaram Hills, Karnataka, southern India. Vulture News 71: 36–49. DOI: 10.4314/vulnew.v71i1.3
Samson A., Ramakrishnan B. 2018. Long-billed vultures: Additional new breeding site of Long-billed vultures (Gyps indicus) in Moyar Valley, Tamil Nadu, Southern India. Zoo's Print 33(1): 23–25.
Samson A., Ramakrishnan B. 2020. The Critically Endangered White-rumped Vulture Gyps bengalensis in Sigur Plateau, Western Ghats, India: Population, breeding ecology, and threats. Journal of Threatened Taxa 12(13): 16752–6763. DOI: 10.11609/jott.3034.12.13.16752-16763
Samson A., Ramakrishnan B., Renuka S., Ravi P., Ramasubramanian S. 2014. Bathing behavior and waterhole importance of White-rumped Vulture conservation in the Sigur Plateau, Tamil Nadu, southern India. Journal of Applied Science and Research 2(5): 92–99.
Santangeli A., Girardello M., Buechley E., Botha A., Di Minin E., Moilanen A. 2019. Priority areas for conservation of Old World vultures. Conservation Biology 33(5): 1056–1065. DOI: 10.1111/cobi.13282
Şen B., Tavares J.P., Bilgin C.C. 2017. Nest site selection patterns of a local Egyptian Vulture Neophron percnopterus population in Turkey. Bird Conservation International 27(4): 568–581. DOI: 10.1017/S0959270916000411
Sergio F., Marchesi L., Pedrini P. 2004. Integrating individual habitat choices and regional distribution of a biodiversity indicator and top predator. Journal of Biogeography 31(4): 619–628. DOI: 10.1046/j.1365-2699.2003.01002.x
Sibly R.M. 1983. Optimal group size is unstable. Animal Behaviour 31(3): 947–948. DOI: 10.1016/S0003-3472(83)80250-4
Srinivasulu C., Srinivasulu B., Venkateshwarlu P., Seetharamaraju M., Kaur H., Sreekar R. 2009. Present status of critically endangered species of Gyps in Andhra Pradesh, India. Current Science 96(4): 449–450.
Stotrabhashyam S., Reddy B., Satla V., Siddiqui I. 2015. A breeding site record of Long-billed Vulture Gyps indicus (Aves: Accipitriformes: Accipitridae) from Bejjur Reserve Forest, Telangana, India. Journal of Threatened Taxa 7(1): 6800–6804. DOI: 10.11609/JoTT.o4014.6800-4
Subramanya S., Naveein O.C. 2006. Breeding of Long-billed Vulture Gyps indicus at Ramanagaram hills, Karnataka, India. Indian Birds 2(2): 32–34.
Tapia L., Zuberogoitia I. 2018. Breeding and Nesting Biology in Raptors. In: J.H. Sarasola, J.M. Grande, J.J. Negro (Eds.): Birds of Prey. Cham: Springer. P. 63–94. DOI: 10.1007/978-3-319-73745-4_3
Tarboton W.R., Allan D.G. 1984. The Status and Conservation of Birds of Prey in the Transvaal. Transvaal Museum Monograph 3. Pretoria: Transvaal Museum. 115 p.
Thakur M.L., Narang S.K. 2012. Population status and habitat-use pattern of Indian White-backed Vulture (Gyps bengalensis) in Himachal Pradesh, India. Journal of Ecology and the Natural Environment 4(7): 173–180. DOI: 10.5897/JENE11.103
Thiollay J.M. 2006. The decline of raptors in West Africa: Long-term assessment and the role of protected areas. Ibis 148(2): 240–254. DOI: 10.1111/j.1474-919X.2006.00531.x
Venkitachalam R., Senthilnathan S. 2015. Breeding record of Indian vulture (Gyps indicus) in Moyar Valley, Tamil Nadu, India. Current Science 109(2): 258–259.
Venkitachalam R., Senthilnathan S. 2016. Status and population of vultures in Moyar Valley, southern India. Journal of Threatened Taxa 8(1): 8358–8364. DOI: 10.11609/jott.2522.8.1.8358-8364
Vergara P., Gordo O., Aguirre J.I. 2010. Nest size, nest building behaviour and breeding success in a species with nest reuse: the white stork Ciconia ciconia. Annales Zoologici Fennici 47(3): 184–194. DOI: 10.5735/086.047.0303
Verlando A., Márquez J.C. 2002. Predation risk and nest-site selection in the Inca tern. Canadian Journal of Zoology 80(6): 1117–1123. DOI: 10.1139/z02-09
Vlachos C.G., Papageorgiou N.K., Bakaloudis D.E. 1998. Effects of the feeding station establishment on the Egyptian Vulture Neophron percnopterus in Dadia Forest, north eastern Greece. In: R.D. Chancellor, B.U. Meyburg, J.J. Ferrero (Eds.): Holarctic Birds of Prey. London: ADENEX-WWGBP. P. 197–207.
Wagley K., Devkota R.P., Bhusal K.P., Dhamala M.K. 2020. Breeding success of the Himalayan griffon (Gyps himalayensis) in Upper Mustang, Nepal. Nepalese Journal of Zoology 4(2): 95–100.
Weaver H.B., Brown C.R. 2005. Colony size, reproductive success, and colony choice in Cave Swallows Petrochelidon fulva. Ibis 147(2): 381–390. DOI: 10.1111/j.1474-919x.2005.00417.x
Xirouchakis S.M. 2010. Breeding biology and reproductive performance of Griffon Vultures Gyps fulvus on the island of Crete (Greece). Bird Study 57(2): 213–225. DOI: 10.1080/00063650903505754
Xirouchakis S.M., Mylonas M. 2005. Selection of Breeding Cliffs by Griffon Vultures Gyps fulvus in Crete (Greece). Acta Ornithologica 40(2): 155–161. DOI: 10.3161/068.040.0211
Young T.P. 2000. Restoration ecology and conservation biology. Biological Conservation 92(1): 73–83. DOI: 10.1016/S0006-3207(99)00057-9