Abstract
The present investigation is undertaken to understand the cause of the sudden mass mortality of Spot-billed Pelicans (Pelecanus philippensis) that have mixed colonies with Painted storks (Mycteria leucocephala) at Bird Migration Site, Telineelapuram Village, Tekkali Mandal, Srikakulam District, Andhra Pradesh. Post-mortem examination of the gastrointestinal tract (GIT) of a single pelican was conducted along with the faecal analysis of both birds using Mac Master floatation technique. The infected proventriculus of pelican was studied histopathologically. Adult nematode parasites collected were identified and described using light and scanning electron microscopy (SEM). Faecal analysis of 25 birds (15 pelicans and 10 storks) showed 100% prevalence of infection. Post-mortem revealed very high parasite burden with as many as 1967 parasites in four stages i.e. 316 third larval stage (L3), 652 fourth larval stage (L4), 573 immature adult and 426 mature adult nematode parasites. These nematodes were found attached to mucosal surface of the proventriculus, obstructing the lumen, causing haemorrhages and revealing some histoarchitectural changes at the histopathological level. Adult parasites were identified as Contracaecum species i.e. C. micropapillatum and C. multipapillatum. This is the first record of Contracaecum species in the proventriculus of a wild spot-billed pelican at Srikakulam District. Overall, the present study alerts the occurrence of sudden mass mortalities in migratory birds like pelicans and storks due to heavy infections and stresses the importance of implementing timely preventive measures to safeguard the avian fauna.