Foraging behaviour and feeding success of the black‐necked stork (Ephippiorhynchus asiaticus) in Dudwa National Park, Uttar Pradesh, India

Abstract

Foraging behaviour of the black-necked stork (BNS) Ephippiorhynchus asiaticus was studied in 1996 and 1997 in Dudwa National Park (DNP), Uttar Pradesh, India. The storks were observed using tactile and visual techniques to catch ®sh. Of the 929 ®sh seen caught in 2 years, 894 (96%) were caught by a tactile mode of feeding and the remaining 35 (4%) by a visual mode of feeding. The rate of foraging attempts by BNS¯uctuates with that of season in DNP and coincides with prey abundance. Immediately after the monsoon when the water level was high, BNS had to search for prey more often, as the prey became widespread. Whereas in summer when the water level decreased, the concentration of the ®sh was higher, which helps BNS to catch ®sh in quick succession. Prey behaviour and the condition of the wetland determined the selection of the tactile foraging technique among the BNS in DNP. The black-necked storks were more successful in the early hours of the day (06:00±10:00) and they were generally more successful or preferred to feed on medium-sized ®sh (i.e. 5±10 cm) in DNP. Prey pro®tability was highest for larger size ®sh and decreased as the prey size decreased. Principal component analysis showed that prey size, handling time of each prey, the month and water depth determined foraging success in 1996 and 1997.

Time-activity budget of the Black-necked Stork Ephippiorhynchus asiaticus during non-breeding season in India

“…Aggressive behaviour (towards intra-and inter-species) was more during winter (percent time ± SE) (2.25 ± 0.68) than summer (0.62 ± 0.21) (t = 2.277, P<0.01). Our earlier (see Maheswaran, 1998) observations indicate that the storks territoriality increased as food resources became depleted. Most (>50%) of the aggressive encounters were observed between 0600 and 1000hr.…”

“…The next day another bird was observed continuously so that two days were spent in each of the three wetlands alternatively to study the male and female individuals. Black-necked Storks are highly territorial (Maheswaran, 1998) and can be seen in their respective territories, so finding a particular bird (either a male or a female; distinguished by iris colour) was not difficult. During summer, due to less water level in the wetlands storks disappeared constantly (before forest department started pumping water) from their respective wetlands and this made it difficult for us to locate the focal pair.…”

“…Knowledge about the daily activity pattern of the Black-necked Stork is very essential in order to conserve the species as it declined drastically in the whole of the SouthEast Asia, and especially in India (Maheswaran et al, 2004). In India, ecological studies on Black-necked Stork have been conducted at Keoladeo National Park in Rajasthan (Ishtiaq, 1998), Dudwa National Park in Uttar Pradesh (Maheswaran, 1998;Maheswaran & Rahmani, 2001, 2002& 2005 and in Etawa and Mainpuri districts in Uttar Pradesh (Sundar, 2003).…”

Foraging technique and prey‐handling time in black‐necked stork (Ephippiorhynchus asiaticus)

“…This could be one reason why black-necked storks in Dudhwa mostly used a tactile mode of feeding. Although we did not collect any data with regard to the habitat condition to correlate with the use of a tactile foraging technique, in general, wetlands in Dudhwa are shallow and turbid and support fish species such as Indian catfish (mud-dwelling fish species), the most preferred prey item of the black-necked stork in Dudhwa (Maheswaran & Rahmani 2002). However, further studies are required to examine changes in the foraging strategy of black-necked storks, if any, in relation to habitat conditions such as turbidity and water level.…”

Foraging Ecology of the Painted Stork (Mycteria leucocephala): A Review

“…However, the Saddlebill (E. senegalensis) can be observed foraging in muddy waters, catching prey by tactolocation in a manner similar to Mycteria (del Hoyo et al 1992) and the Black-necked Stork (E. asiaticus) is also known to employ tactile foraging. Fish captured are generally brought to dry ground and then swallowed (Maheswaran and Rahmani 2002) which is in contrast to Mycteria who complete all foraging in the water. Leptoptilos have straight, thick and slightly upturned bills and forage visually, on fish and a variety of other items, including offal at garbage dumps (Hancock et al 1992).…”