Environment

Great Indian Bustards adapt to produce 2-egg clutch

The Great Indian Bustard. File.

The Great Indian Bustard. File.

The perceived beliefs and recorded observations pertaining to the egg-laying habits of the Great Indian Bustard (GIB) have changed after the recent excessive rains in western Rajasthan. The critically endangered bird species has adopted an altogether new habit of laying a clutch of two eggs at a time after having a diet with additional proteins during the monsoon season.

Environmentalists in Rajasthan have hailed it as a new record as all experts had been reporting a clutch of a single egg by GIBs all through its natural history of more than a century. Scientists working on ex situ breeding of these endangered birds have discovered the new proclivity in Jaisalmer district's Desert National Park (DNP).

Four female GIBs laid two eggs at a time during the current rainy season in the DNP, while two others were observed laying clutches of two eggs each earlier in the 2020 season. Dehradun-based Wildlife Institute of India's (WII) scientist Sutirtha Dutta, who is leading the project for the breeding of the rare species, told The Hindu that six nests with two eggs each had been detected so far in the DNP.

Dr. Dutta said 5% to 10% of the female GIBs had been detected in the past laying two eggs each, but the high incidence, with the signs of an evolving habit, had been observed for the first time. “The natural feed for birds gets produced in abundance whenever it rains excessively in the DNP,” he said. The rains exceeded 20 mm by mid-August in Jaisalmer district. As the GIB, which is the State bird of Rajasthan, survives mainly on reptiles, gerbils, grasshoppers, large insects and locusts, a rich quantity of feed was produced this year, providing additional proteins to the endangered birds, which have doubled their clutch size “in happiness”.

The WII's team has been working on ex situ breeding of GIB for the last three years. Dr. Dutta said the team had picked up one egg from each nest to be incubated and hatched under artificial conditions at a facility established near Sam in Jaisalmer district. The remaining eggs were left within the natural nests of the females to be hatched.

Aimed at preserving the GIBs, whose population has reduced to less than 150 in the wild, the breeding project focuses on spatial prioritisation, risk characterisation, and conservation management with the endangered species. The laying of clutches of two eggs in 2020 aroused immense curiosity, after which the WII’s experts became vigilant in monitoring the nests to assess if such an instance would get repeated. The team has considered the GIBs’ new habit as an important element of the project’s progress.

The State government's Forest Department started the breeding project in collaboration with the WII to raise the new stock of GIB chicks in 2019 after a long wait by environmentalists for nearly four decades. Secretary of the Tourism and Wildlife Society of India (TWSI), Harsh Vardhan, said that though the bird species had been facing the threat of its extinction, the breeding project took off only after it vanished in Andhra Pradesh, Karnataka, Maharashtra and Madhya Pradesh.

The GIB is now found in a small number only in western Rajasthan, while Gujarat claims to have a few females left in its Banni Grassland Reserve. When the project commenced, the Forest Department invited experts from the Abu Dhabi-based International Fund for Houbara Conservation to stay at the DNP and provide guidance at the new breeding facility for GIBs.

Mr. Vardhan said the egg-laying aspect of GIBs had received lively attention at an international symposium on bustards organised in Jaipur in 1980. Most of the experts who attended the event were unanimous that the GIB laid only a single egg, while renowned ornithologist Salim Ali had opined that the bird laid more than one egg. The citing by British ornithologists during the colonial period were also in favour of the GIP laying one egg at a time.


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Printable version | Aug 19, 2022 12:23:32 pm | https://www.thehindu.com/sci-tech/energy-and-environment/great-indian-bustards-recorded-as-laying-two-eggs-after-excessive-rains/article65784663.ece