Ravikanth Manchiryala - Department of Zoology and Wildlife Biology, A.V.C. College (Autonomous), Mannampandal-۶۰۹ ۳۰۵, Mayiladuthurai, (affiliated to Bharathidasan University, Tiruchirappalli), Tamil Nadu, India
Baskaran Nagarajan - Department of Zoology and Wildlife Biology, A.V.C. College (Autonomous), Mannampandal-۶۰۹ ۳۰۵, Mayiladuthurai, (affiliated to Bharathidasan University, Tiruchirappalli), Tamil Nadu, India

Gyps species declined rapidly between late ۱۹۹۰s and early ۲۰۰۰s in southern Asia owing to the use of diclofenac, and are listed as Critically Endangered species. Long-term data on breeding ecology is essential to understand the population trend of these threatened species. This study assessed the reproductive phenology and reproductive performance of two critically endangered Gyps species—Long-billed Gyps indicus (LBV) and White-rumped G. bengalensis (WRV) vultures—through long-term monitoring at breeding colonies in Kaghaznagar and Sironcha Forest Divisions in the Deccan Plateau of India between ۲۰۱۰ and ۲۰۲۱. LBV began their nest construction and copulation in the second week of October, and ended in the fourth week of November, while the WRV completed the same between the first and second weeks of October. LBV started egg-laying during the first week of December and ended in the first week of January, with a peak during the third week, on December ۱۴, and the mean incubation period was ۵۴±۱ days. The WRV completed their egg-laying early, during the second and third weeks of October, and peaked during the second week, on ۱۴th and had relatively longer incubation of ۶۱±۱ days. In LBV, hatching peaked during the first week of February, and mean nestling period was ۱۰۳±۲, while in WRV hatching was peaking much earlier during the third week of December and the mean nestling period was ۱۰۵±۱ days. Overall nest success, breeding success, and productivity estimated based on ۱۵۹ breeding pairs of LBV observed over ۱۲ years were lower compared to that of ۱۲۴ breeding pairs of WRV observed over ۶-year period. The decline in breeding success of LBV since ۲۰۱۹ is discussed in the light of poisoning of the cattle reported in ۲۰۱۸, and the reopening of Sirpur, Kaghaznagarpaper industry in ۲۰۱۷ that discharges its hazardous effluent into the Peddavagu stream. Therefore, the present study suggests long-term monitoring of the breeding colonies including evaluating the drivers of population and breeding, molecular and toxicological studies, and implementation of Vulture Safe Zones to save these critically endangered Gyps vultures from local extinction.

Breeding success, egg-laying period, fledgling, hatching, incubation period, nesting success, productivity of vultures