Cormorants, described as 'foot-propelled pursuit divers', constitute an important component of aquatic food webs and exhibit unique foraging behaviour patterns, which can be properly understood through a comparative study. Since, after a foraging dive they surface to ingest the prey, the intensity of kleptoparasitic attacks on the surface can have a major impact upon the net energetic gain for each individual. Inspite of the fact that cormorants and their habitats are severely threatened in India, their foraging behaviour has not been adequately studied. Such considerations prompted us to undertake field studies on three sympatric cormorants (Phalacrocorax spp.) at 60 different sites in the Delhi region of North India, during 2004-2007. By means of video photography, some key foraging parameters including group size, prey size and patterns of kleptoparasitic attacks were quantified. Along a loose body size gradient, we observed significant differences among the three species with respect to not only their preference for wetland size but also prey size. The frequency of a kleptoparasitic attacks depended upon the group size and foraging behaviour of each species. It was observed that several foraging bouts were abruptly terminated due to human disturbances, mostly at sites lying outside the protected areas. This observation points towards the need to conserve small waterbodies in the countryside, currently threatened by pollution and urbanization, for the benefit of a variety of waterbirds including cormorants.

Measurements of morphological features are important for ecological studies, especially on free‐ranging wild animal species. Conventionally, specimens either dead or in captivity are used for morphometric studies, which is difficult in the case of wild species for several reasons. Capturing would be even futile when research questions are relating to issues such as prey size selection or estimation of intake rate under field conditions, where in situ morphometric measurements are inevitable. Remotely estimating morphometric features via, avian bill and head lengths are always laden with wide variances. Hence, we developed this technique for in situ measurements of animal morphology through digital photographs. This non‐invasive novel method for in situ estimation of individuals’ morphometric measurements uses digital photographs’ metadata. We extracted the metadata (field of view, focal length, subject‐distance, etc.,) in exchangeable image file format from digital images using freely available software, and the unknown sizes were estimated from each image. Cardboard (fish) models were, at first, used to estimate the accuracy of measurements comparing actual and estimated values, and the same protocol was repeated on museum specimens (bird). Finally, we checked the repeatability of this method under field conditions using free‐ranging Chickens (Gallus gallus domesticus). The results under different conditions were subjected to rigorous statistical testing. Upon comparing the actual with estimated values, obtained from three distinct types of objects (1. Cardboard model, 2. Museum specimens and 3. Live birds under field conditions), variations were found non‐significant affirming the assumption that actual value (Y) = estimated value (X) with inconsequential variance of the Y from X. Moreover, both the relative and absolute errors between the actual and estimated values were so low, indicating that this method yielded neither overestimation nor underestimation. The advantage of this non‐invasive method is that it could generate reasonably accurate morphometric measurements at a relatively low cost for routine morphometric works in field conditions. We envisage significant utility of this non‐invasive technique in different fields of science such as biology, morphology, ecology, evolution, wildlife, conservation science, agriculture, forensics and engineering design.

Resource partitioning is well known along food and habitat for reducing competition among sympatric species, yet a study on temporal partitioning as a viable basis for reducing resource competition is not empirically investigated. Here, I attempt to identify the mechanism of temporal partitioning by intra- and interspecific diving analyses of three sympatric cormorant species at different freshwater wetlands around the Delhi region. Diving results indicated that cormorants opted for a shallow diving; consequently, they did not face any physiological stress. Moreover, diving durations were linked with seasons, foraging time and foraging habitats. Intraspecific comparison suggested that cormorants spent a longer time underwater in early hours of the day. Therefore, time spent for dive was higher in the forenoon than late afternoon, and the interspecific analysis also yielded a similar result. When Phalacrocorax niger and Phalacrocorax fuscicollis shared the same foraging habitat, they tended to differ in their foraging time (forenoon/afternoon). However, when P. niger and Phalacrocorax carbo shared the same foraging time, they tended to use different foraging habitats (lentic/lotic) leading to a mechanism of resource partitioning. Thus, sympatric cormorants effectively use time as a resource to exploit the food resources and successful coexistence.

Across disciplines—biological, ecological, evolutionary, or environmental—researchers increasingly recognize the importance and the need for cost-effective, non-invasive techniques for in-situ morphological measurements of organisms in diverse research contexts. By applying a non-invasive technique using digital images taken under field conditions, we successfully measured the body sizes of wild Painted Storks (Mycteria leucocephala) in two different biogeographic regions of India, spatially separated by 20° of latitude. We have used the wild Painted Storks as model species for measuring their morphometrics using a non-invasive technique that could easily be applied to similar species, rare, endemic, colonial, aquatic, and even those with cultural taboos. Our results satisfactorily classify and predict the sexes of the species and their biogeographic origin based on independent morphological variables using Machine Learning algorithms. The BayesNet yielded the correct classification instances (Receiver Operating Characteristic (ROC) = 0.985), outperforming all the other tested classifying algorithms. A strong relationship was observed between the local bioclimatic conditions and the morphological variations in wild Painted Storks reflecting clear eco-geographic patterns. Without this non-invasive technique, it would be almost impossible to collect morphological measurements at a large scale from live birds under field conditions. Our study is a testimony to the effectual use of the non-invasive digital method for in-situ measurements from free-living wild species in the field, assuming significance, especially from climate change perspectives, biology, ecology, and conservation.

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Digital images have become cheap, yet its perspective issues cause hindrance for size and shape estimations. Here, we quantified shape distortions due to projective issues using Cardboard model fishes. We identified that Generalized Procrustes Analysis preserves shape homogeneity where objects differ in angle up to 20°are grouped as similar ones. For 2D shape analysis, the proposed novel filter criterion aids in profitable use of images with minor projective issues. Using the proposed filter criterion images of free ranging Painted Storks (Mycteria leucocephala), taken under field conditions, were subjected for shape analysis. Our result indicates that a subtle difference was noted in the mandibular shape of Painted Storks between two habitats viz., Delhi Zoo and Keoladeo National Park, which indicates a cue of intra and interspecific competition. This study deserve merits as the entire exercise has been done without disturbing or capturing birds which highlights the value of animal welfare.

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