FOOD-NICHE PARTITIONING AMONG SYMPATRIC KINGFISHERS IN BHITARKANIKA MANGROVES, ODISHA

Volume: 109Start Page: 72End Page: 7

Metabarcoding for parallel identification of species, sex and diet of obligate scavengers: an application to globally-threatened Gyps vultures

After suffering a massive decline (~ 99%) in numbers caused by feeding on livestock carcasses containing the nephrotoxic drug diclofenac, critically endangered Gyps vultures now persist in low numbers in the Indian subcontinent. Most are concentrated near National Parks, likely due to availability of wild carcasses free from toxic veterinary drugs. Quantification of vulture diets is critical to test this hypothesis. We describe a validated “field-to-benchtop-to-desktop” metabarcoding workflow for assessing species- and sex-specific diet of these obligate scavengers from non-invasively collected faecal samples. Seven metabarcodes were designed to simultaneouslsy identify the vulture species, sex and diet. Amplicons generated from multiplex PCRs were indexed and sequenced on an Illumina Miseq platform. We included controls and three replicates per sample to establish a series of non-arbitrary thresholds to filter the sequence data and eliminate cross-contamination, PCR/sequencing errors and false positives. This strategy enabled identification of species and sex for all samples and dietspecific sequences with high taxonomic resolution for 97% of samples. Just four (two for diet, one each for vulture species and sexing) metabarcodes were sufficient to meet the objectives. This preliminary analysis suggests that domestic livestock is the most frequently consumed diet item across samples from inside and outside protected habitats. Our method provides a rapid and reliable tool for describing large-scale variation in consumption of domestic versus wild species in the diet of these scavengers, paving the way for a better understanding of the role protected areas play in persistence and recovery of the remaining Gyps vultures in the wild.The study was funded in parts through Grants received from NCBS (NCBS-4138; UR) and the Raptor Research and Conservation Fund (RRCF-10/08/2018/No. 13; MGH)

Spatial patterns in the diet of Gyps vultures in India and their implications for conservation

Dietary analyses are particularly useful for developing conservation programmes for species threatened by resource depletion, poisoning and environmental pollution. Gyps vultures in South Asia represent one such case, having undergone a population collapse caused by feeding on carcasses of cattle treated with the non-steroidal anti-inflammatory drug diclofenac. Following a ban on the veterinary use of diclofenac, populations of vultures remain low and mostly concentrated near protected areas. Understanding the role of protected areas in the recovery of these critically endangered species requires analyses of spatial variation in their diet. We used faecal metabarcoding to investigate the spatial variation in the diet of Gyps vultures across four landscapes from sites located inside and outside protected areas. We collected faecal 642 samples, of which 419 yielded adequate molecular data to identify the vulture species and 30 molecular operational taxonomic units corresponding to at least 28 diet species. The diet was dominated by large ungulates and varied across landscapes, protection status and vulture species, with the observed variation largely explained by differential intake of wild and domestic species. Domestic livestock was present in >95% of the samples from Central, West and North India, but 77% of the samples had only wild species in South India. This variation was explained by livestock density within 100 km radius of the sampling site. Our results imply that protected areas may not offer a respite from possibility of diclofenac-poisoning across most parts of the country and efforts should continue unabated to remove nephrotoxic drugs from veterinary use

Niche filling slows the diversification of Himalayan songbirds

Speciation generally involves a three-step process—range expansion, range fragmentation and the development of reproductive isolation between spatially separated populations1,2. Speciation relies on cycling through these three steps and eachmay limit the rate atwhich new species form1,3. Weestimate phylogenetic relationships among all Himalayan songbirds to ask whether the development of reproductive isolation and ecological competition, both factors that limit range expansions4, set an ultimate limit on speciation. Based on a phylogeny for all 358 species distributed along the eastern elevational gradient, here we show that body size and shape differences evolved early in the radiation, with the elevational band occupied by a species evolving later.These results are consistentwith competition for niche space limiting species accumulation5. Even the elevation dimension seems to be approaching ecological saturation, because the closest relatives both inside the assemblage and elsewhere in the Himalayas areon average separated bymore than fivemillion years,which is longer than it generally takes for reproductive isolation tobe completed2,3,6; also, elevational distributions are well explained by resource availability, notably the abundance of arthropods, and not by differences in diversification rates in different elevational zones.Ourresults imply that speciation rate is ultimately set by niche filling(that is, ecological competition for resources), rather than by the rate of acquisition of reproductive isolation

Intensity of haemosporidian infection of parids positively correlates with proximity to water bodies, but negatively with host survival

In birds, haemosporidian parasites have been found to have direct pathogenic effects on the host with important consequences for their fitness. However, less is known about distribution patterns of parasite vectors, which may significantly affect parasite prevalence, infection intensity and, thus, pathogenicity in hosts. Here, we tested for relationships between infection intensity, survival, predation and distance from water bodies of mixed-species tit flocks. We found that the prevalence of Haemoproteus and Plasmodium infections decreased with increasing distance from forest lakes and bogs outside the bird breeding season. Haemoproteus and Plasmodium parasites were found to be associated with a low survival rate of willow tits (Poecile montanus) in the vicinity of water bodies, while crested tits (Lophophanes cristatus) were affected only by Haemoproteus. Crested tits, a dominant species of parid social groups, had a lower parasite prevalence and they survived better than the subordinate willow tit. This can be explained by the crested tits foraging higher in the pine canopy as parasite vectors supposedly cannot reach hosts in the upper canopy as equally as in lower parts of the canopy. We show that individuals staying in flocks further from the forest water bodies and spending more time foraging in the upper parts of the canopy have higher chances of survival into the next breeding season. This suggests that different forest and canopy areas may differ in terms of parasite risk and associated mortality. Finally, we found that the infection status of parids increases the probability of predation by the pygmy owl (Glaucidium passerinum). We conclude that distance from water bodies and foraging location in the forest canopy may affect the intensity of parasite infection with fitness consequences in wintering parids