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Open Access Research Issue
Diet and habitat affinities in six raptor species in India
Avian Research 2018, 9 (1): 36
Published: 29 October 2018
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Background

Sympatric species adapt to, and temporally or geographically segregate access to similar limiting factors.

Methods

We compared nesting habitat and diet affinities of six raptor species in central India between the years 2006-2015.

Results

A large composition of reptiles in the diet was characteristic for Circaetus gallicus, Spilornis cheela and Elanus caeruleus, while Aquila fasciata, Falco chicquera and Nisaetus cirrhatus show a higher proportion of birds. Species with greatest similarity of diet were C. gallicus and S. cheela. Considering the environmental characterization of areas where raptors built the nest, some species were ecologically closer than others. N. cirrhatus and S. cheela were related to the presence of water bodies, dry deciduous forest and evergreen forests, while E. caeruleus and C. gallicus preferred more open habitats. A. fasciata bred either on cliffs or trees, F. chicquera on trees or mobile towers, and the other four species built their nests exclusively in trees.

Conclusions

We conclude that although there was overlap in diet and nesting ecology for a number of species, the geographical separation likely limits competition for resources.

Open Access Research Issue
A tale of two tails: asymmetry in Great Grey Shrike (Lanius excubitor)
Avian Research 2018, 9 (1): 1
Published: 08 January 2018
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Downloads:29
Background

Asymmetry in the wild is a controversial, and to date, unresolved subject. Fluctuating asymmetry (FA) is the developmental instability (intra-individual variation) while, directional asymmetry (DA) expresses the asymmetry of the population mean.

Methods

We analysed 63 Great Grey Shrike (Lanius excubitor) skins at the Naturalis Biodiversity Center, Leiden, the Netherlands. The black markings on the tails were digitized in order to evaluate the symmetry of the two sides of each shrike. Ptilochronology helped understand if nutritional condition affected symmetry.

Results

ANOVA revealed no significant differences in size of the tail between sexes (F = 1.67, p > 0.05). However, there was significant difference in the shape of the black area in feathers between the sexes (F = 2.14, p < 0.05), and males had more elongated and slender black areas. Further, DA was observed only in males, but FA was noted in both sexes. Spearman correlation showed no significant association between FA score and tail features in both the sexes. However, in females, we observed a negative significant correlation between the number of fault and growth bars. The shape of the black area in the tail displayed no statistically significant association with the tail features in both sexes although growth bars influenced tail shape more than the number of fault bars.

Conclusions

We concluded that the characteristics discovered by us need to also be checked in the field and if they can be used to sex individuals. Also, chromatic manipulative studies are require to verify if DA influences sexual selection in the Great Grey Shrike.

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