Articles

a list of articles, publications, poster and reviews of harrier research from the project

Detour migration to circumvent the Himalayas in the Montagu’s Harrier Circus pygargus - Movement EcologyBackground Migrating birds do not always travel along the shortest possible routes between breeding and wintering sites. Rather, detours are a common phenomenon in response to availability of foraging habitats, generic wind patterns, predation risk, and ecological barriers. The Himalayas are a formidable ecological barrier within the Central Asian Flyway (CAF), but hitherto research has focused on high-altitude flights of species that cross the Himalayas, and thus information on species that circumvent this mountain range is lacking in this understudied migration system. Methods We tracked Montagu’s Harriers Circus pygargus for 5 years from their wintering range in India, and found that these long-distance migrants travelled by a grand westward detour around the Himalayas to their breeding areas in Kazakhstan. We calculate the energetic optimality of the detour on the basis of a well-known theoretical model and explain the general migration patterns of Montagu’s Harriers in the CAF. Additionally, we compare ecological factors such as ground elevation, habitat greenness (NDVI), land cover and wind patterns along the actual migration route with the hypothetical shortest route to explain why Montagu’s Harriers follow a detour migration pattern in the CAF. Results The observed (detour) route was on average 1245 ± 94.4 km (27%) longer than the hypothetical shortest direct route. The detour did seem to be optimal for Montagu’s Harriers as per the model that considers a distance of up to 1288 km to be optimal. With the detour, harriers circumvented the high altitudes of the Himalayan plateau, effectively avoiding high ground elevations over 4000 m above mean sea level (AMSL). Harriers followed the same detour during spring and autumn migrations, encountering both supporting and opposing winds, and thus the detour cannot be explained by generic wind patterns. The detour was facilitated by the availability of open natural ecosystems (ONEs) and stopover sites with higher productivity west of the mountain range along the floodplains of the Amu Darya river and in the Thar Desert during spring and autumn respectively. Conclusion We argue that circumventing the mountain range, as illustrated by our pioneer study on the Montagu’s Harrier, could be a common behaviour among migrating landbirds in the CAF. We also emphasize the importance of the protecting ONEs along the western detour for the long term conservation of migratory birds in the CAF.

Stopover by migrant Montagu's Harriers in the Thar Desert is determined by vegetation greenness and grasshopper abundance but not locust outbreaksFood availability is an important criterion for migrant birds' decision to stay or leave a stopover site. This can vary depending on the conditions at…

First report of moth species of the family Tineidae (Lepidoptera) in regurgitated pellets of harriers in India Caterpillars of Tineidae moths mainly feed on keratin sources and require moisture and warm temperature for emergence. The presence of Tineidae moth caterpillars, pupae, and adults in regurgitated pellets of harriers, diurnal migratory raptors wintering in India, suggests a potential dietary association and highlights the importance of considering associated organisms in raptor diet estimation studies. The caterpillars preferred rodent hairs present in the pellets over feather and arthropod remains. This is the first record of Tineidae moths on the pellets of harriers.

The long way might just be the right way for Montagu’s harriersEvery year, Montagu’s harriers — slim, graceful raptors with striking wingspans — journey thousands of kilometres between their breeding grounds in Central Asia and their winter homes in India. But instead of flying the shortest possible route, which goes through the Himalayas, these birds take a longer, winding path around the mountain range which adds […]

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Flight Of The HarrierThe migratory journey of a male Montagu’s Harrier from Gangewadi to Kazakhstan down the years highlights the importance of protecting grassland habitats.

Diet of Montagu's Harriers Circus pygargus Wintering in India: Analysing Seasonal, Regional and Sex Differences Using Web-Sourced Photographs and Pellet ContentsStudies on the diet composition of bird species provide valuable insights on their habitat use, trophic interactions and prey selection. Prey abundance can drive movements of raptors in their wintering grounds. But such links have been difficult to establish due to the lack of dietary information for most raptor species. Estimating the wintering diet of raptors is a challenge that requires extensive fieldwork across a large geographical area which is often not possible. The methods used in breeding sites such as nest observations are not available in the non-breeding regions. Recently, several studies have demonstrated the use of web-sourced photographs as a tool for understanding the diet of raptors and also the need for combining multiple approaches to get a comprehensive overview of diet. In this study, we use a novel approach by using web-sourced photographs and pellets to estimate the variations in the diet of Montagu's Harrier Circus pygargus, a species in decline, across its wintering range in India. A total of 232 photographs and 391 pellets collected across western India, Deccan and south India during autumn, winter and early spring seasons were analysed. About 53% of photographs and 71% of pellets contained orthopterans, forming the major component of the harrier's diet. The proportion of reptiles, eggs and birds in the diet were similar across both methods. Presence of other insects in the diet was better estimated by photographs (23%) than pellets (8%) while rodent presence was higher in pellets (17%) than photographs (4%). Pellet analysis and photographs showed similar variation in diet across seasons while only pellets showed variation in diet across regions. Photographs also showed that there is significant variation in diet between the sexes of the species, with higher presence of insects and reptiles in the diet of males than females. Our results suggest that a combination of photographs and pellet analysis provide better estimates of wintering diet of Montagu's Harriers.

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How the decline in India's harrier population hurts its farmersOn World Wildlife Day on Friday, a focus on a critical species that feeds on the locusts and grasshoppers that could damage crops.

Exodus at RollapaduThe grasslands around Rollapadu, a village in Andhra Pradesh’s Kurnool district, was declared a sanctuary in 1988 to protect the dwindling populations of the cr

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Harriers that winter in India are decliningA compilation of harrier roosts in India suggests that the wintering populations of these migrant birds of prey have declined between 1985 and 2015. “Harrier roost counts have shown a declining trend, not just in human-dominated sites but also in protected areas created for conservation of grassland fauna,” said M. B. Prashanth, a researcher at […]

Flying into trouble: Harrier birds decline as grasslands disappearIndia has some of the largest roosting sites of this migratory species.

Migratory harrier birds are no longer flocking in large numbers to IndiaOne of the main reasons for the decline in harrier numbers is the destruction of the grasslands in both breeding and wintering areas, according to scientists.

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