Wildbuzz | Loop of rosefinches and return of the natives
One of the questions that fascinates children and adults alike is how do birds migrate and do they eat during their annual journeys? A fascinating study by Swedish researchers has lent insights into the “loop migration” of the common rosefinch from Sweden to India and back using different routes in autumn and spring.punjab Updated: Apr 09, 2017 14:32 IST
One of the questions that fascinates children and adults alike is how do birds migrate and do they eat during their annual journeys? A fascinating study by Swedish researchers has lent insights into the “loop migration” of the common rosefinch from Sweden to India and back using different routes in autumn and spring. The rosefinch, which is observed during winters and spring in the tricity region, is a small bird of a length 13-15 cms. Researchers attached light-level geolocators on the backs of rosefinches after trapping them in Sweden. Geolocators are devices which track bird movements by accumulating time-stamped light data as the bird flies. The researchers access that data by recapturing the bird after a successful migratory journey and download the data to a computer.
The researchers, R Stach, C Kullberg, S Jakobsson, K Ström, and T Fransson found that rosefinches moved from Sweden between late July and early August towards east-southeast across Russia and Central Asia before making for Western India. The rosefinches often flew alone and at night during their epic journey. During this autumn migration, rosefinches made long stops (19 to 28 days) to take advantage of food abundance. On their way back to Sweden the following spring, the birds took routes which were more southerly as compared to autumn migration. The reason was that Central Asian deserts are extremely dry in autumn, but rain during winter makes the vegetation in the desert area flourish that allows birds to use the desert zone for stopover in spring.
The other fascinating aspect was that on their return migration, rosefinches were faster! They wanted to reach summer breeding grounds in Sweden early and be favourably placed for mate selection!
RETURN OF THE NATIVES
The UT animal husbandry and fisheries department is keeping a close watch on Sukhna lake’s fish biodiversity due to high evaporation, low rainfall and Skymet’s forecast of a below-normal monsoon. The lake had dried up in June 2012 leading to fish mortality. A number of large fish had to be taken out and rehabilitated at the Government Fish Seed Farm near the regulator-end. The falling water-level has impacted the second phase of release of 5,000 seeds of native carp species, rohu, katla and mrigal, to balance exotic carps in the lake. On July 26, 2016, the department had released 5,000 seeds of native carps in the first phase.
‘’We had planned to release 5,000 seeds of native carps in May or June this year but falling water level has led us to review the schedule. We have postponed the release to July or beyond when we expect monsoon rains to rejuvenate the lake. If the seed is released and the lake dries up, the seed will suffer high mortality. The other decision we have taken is to let recreational angling continue till June as it will enable a thinning of exotic, commercial fish and also provide feedback on the fish status at the Sukhna via the keen anglers,’’ department’s joint director Dr Kanwarjit Singh told this writer.
Explaining the logic of releasing native carps, Dr YK Rawal, assistant professor of zoology, Panjab University and member, UT Environment Impact Assessment Committee said, “The removal of big fish from the Sukhna in October 2015 revealed that exotic grass and silver carps were outnumbering indigenous carps. All over Punjab, Haryana and Himachal Pradesh, exotic carps tend to dominate aquatic systems. The katla is a surface feeder, the mrigal a bottom and rohu is a column or in-between feeder. All levels of the Sukhna’s waters will be covered by the three native carps.’’
The drastic cut in water flow of the river Beas from 30,000 cusecs a day to 1,100 cusecs in order to allow repairs of the Harike barrage and canal gates has led to a frantic search for the endangered Indus river dolphin. The population estimate of dolphins carried out by WWF- India’s senior project officer Mohd Shahnawaz Khan established the number of these mammals between 18 and 35 in the stretch from Harike wildlife sanctuary to Beas town. However, following the substantial cut in water with effect from March 27, 2017, teams of WWF-India and wildlife department claimed to have found “four dolphins”, and released photographs of only one of these four.
The question that arises is that why no precautions were taken to safeguard dolphins when the irrigation department had provided prior intimation of the water cut? Officers and WWF-India had available Khan’s research paper published in 2016 (Factors affecting survival of Indus River Dolphin and species tolerance towards anthropogenic pressure), which clearly points out that during period of low flows, dolphins tended to migrate downstream towards the sanctuary. Khan’s research stated that “management interventions should be focused on identified havens for dolphins during low-flow seasons”.
The danger is that during the current and intense cut in Beas waters, some dolphins may have been flushed into the canals or the Sutlej downstream of the barrage. This is a danger that even gharials will face when re-introduced into the Beas (as per the latest proposal) in September 2017.