Waterbird foods: Lesser Adjutant

Surprisingly little is known of many species of large waterbirds such as storks, ibis and spoonbills. The Lesser Adjutant is one such species. Until recently, it was thought to require tall trees in forests to nests. However, surveys in the lowlands of eastern and central Nepal during 2013-15 have found that practically all of the nesting in some of the rice-growing districts are on trees amid fields. Clearly, a lot is needed to be done in the field to understand this species better. Here is my bit.

With my colleagues, I observed Lesser Adjutants for many an hour in central lowland Nepal in the districts of Rupandehi and Kapilvastu. I restrict this blog post to some of the observations we had of the species feeding in the rice paddies.

As has been seen in eastern Nepal, and in Sri Lanka, Lesser Adjutants in Nepal frequent rice paddies during the monsoon. They steer clear of traffic on the roads, and keep at least 20-30 feet from farmers working on the fields.

One morning, we observed three stork feeding together - all three were exceedingly successful in finding earthworms in the flooded rice fields! We watched as each of them found and devoured 5-7 earthworms in just five minutes! The photo below shows one earthworm meeting its end between the massive beak of a Lesser Adjutant.

Another individual seemed an expert at finding insects in the rice fields. In the photo below, a Belastomatid (giant water bug) is swallowed with gusto.

Another individual, shown below, caught and devoured a freshwater crab that seemed too tiny to be of consequence, but clearly kept the stork's attention as it maneuvered the animal into its mouth.

With almost no time wasted the same stork also caught a fish, which nearly escaped. But,down the hatch it went!

Other colleagues and students have seen Lesser Adjutants in Nepal bring snakes to feed chicks at nests. Now, that must have been a treat for all!

(All photos from Rupandehi and Kapilvastu districts in lowland Nepal, Aug 2014.) 

Waterbird foods: Black-necked Stork

Despite their large size and declining population, Black-necked Storks have received relatively little scientific attention. The most prominent study is that carried out by Gopinathan Maheswaran in the managed lakes in Dudwa Tiger Reserve in northern Uttar Pradesh. The storks there were seen to eat fish as their major food.

The unmanaged wetlands amid agricultural fields in western Uttar Pradesh have the largest known population of this species. Here, observations show that fish is not likely their major food - frogs (and reptiles) are! The photographs above show (from top) newly fledged juveniles have already learnt to catch frogs, snails sometimes figure in the diet of juveniles, and large bull frogs make for a great meal and are literally beaten to death by adults before they are swallowed.

(Photo information: top: 21 Jan 2009, Etawah district; middle: 7 Apr 2009, Etawah district; bottom: 12 Apr 2009, Etawah district. I put together all the observations I had made over the years of food items that Black-necked Storks ate, and now have a note in the journal Forktail in case you are really interested.)

Black-necked Stork allopreening

Remember "allopreening"? One bird preens the other as opposed to itself. See the Munia blog entry for an example. This behaviour has been studied by ornithologists quite a bit and general consensus is that it serves to reinforce bonding and is therefore commonly seen during courtship. Some groups of birds allopreen more than others - Black-necked Storks are not among those that are known to indulge in this behaviour. The photo above shows 4-5 month old Black-necked Stork chicks allopreening. In nearly 8 years of observing this species, this is the first time I saw this behaviour. Chicks in the nest are terribly aggressive to each other as they fight for parents' attention and compete for food. Wonder why they need to indulge in this behaviour after fledging from the nest. (Photo taken in Etawah district, Apr 7, 2009)