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Does the stork bring home the owl? Dusky Eagle-Owls Bubo coromandus breeding on Woolly-necked Stork Ciconia episcopus nests
Abstract and Figures
Large raptors frequently reuse nests of other species, but their reliance on nests of largely one species is unusual. In this natural history note, we describe a novel commensal relationship where nests built by Woolly-necked Storks were preferentially reused by Dusky Eagle-owls. Owls showed distinct patterns of preference for both the nest tree species and the location of the nest tree relative to storks’ choices. These observations were made in an ancient cultivated landscape suggesting that novel inter-species interactions may evolve even in extensively human-modified tropical systems.
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... Dusky Eagle Owls are known to reuse or use stick nests of other species. Such observations have been recorded in Haryana where a pair of Dusky Eagle Owls occupied a Woolly-necked Stork's Ciconia episcopus nest (Sundar et al. 2022). With respect to our observation, the primary builder of this particular nest at Nizamabad cannot be verified. ...
Ketupa coromanda aka the Dusky eagle owl is a large owl predominantly seen in the foothills of Himalayas. Through this article we describe the sighting of this owl in Telangana and review the status in India.
... Intraspecific brood parasitism is also a behavioural adaptation recorded in over 200 species (Lyon and Eadie 2008). Others still may opportunistically use other species' empty nests (e.g., Sundar et al. 2022;Thompson et al. 2019). ...
Nest-building is an energetically expensive activity for birds. Consequently, some species opportunistically use other species’ nests. The Hamerkop Scopus umbretta, an endemic sub-Saharan African waterbird, constructs one of the largest nests of any bird in the world. Little is documented on the role of Hamerkop nests in the breeding biology of other avian species. Therefore, we assessed this from the literature and first-hand observations to determine which species use Hamerkop nests and their associated behaviours. We found at least 20 avian species using Hamerkop nests for breeding in 18 African countries. The Barn Owl Tyto alba was the most commonly reported species using Hamerkop nests. Six species actively usurp nests from Hamerkop pairs. Nine species nested inside the nest chamber, and eight nested on top of the structure. This highlights the role of Hamerkop nests in other avian species’ breeding.
Conservation of biodiversity alongside agriculture is now a global priority. Tree-nesting waterbirds have a tenuous relationship with farmlands because their survival requires farmers to retain trees and wetlands amid croplands. Research on such birds is rare on tropical and sub-tropical agricultural landscapes where high human densities and intensive farming ostensibly deteriorate breeding conditions. We explored breeding ecology and nest site selection by the single-nesting Woolly-necked Stork (Ciconia episcopus) in Haryana, north India using 298 nests from 166 locations discovered between 2016 and 2020. We determined the relative strengths of association of nest locations with natural features (trees, wetlands), human presence (habitation) and artificial water sources (irrigation canals) to understand cues used by breeding storks to situate nests. Woolly-necked Stork brood size from 42 successful nests was relatively high (3.1 ± 0.9 SD), with nests close to human habitation and wetlands having smaller broods. Storks showed high nest site fidelity (44.5% of sites used > 1 year), rarely nested on man-made structures (electricity pylons; 8.4%), and distributed nests in a clumped pattern. Woolly-necked Storks situated nests ambivalent to natural features but associated strongly with man-made features (positively with irrigation canals; negatively with human habitation). Contrary to expectations, most nests were not on the tallest trees but on the medium sized, native Dalbergia sissoo though storks situated nests on two tall trees (native Ficus religiosa and exotic Eucalyptus sp.) far more than the trees’ availability. All three tree species were favoured either for traditional agroforestry or local religious beliefs. Traditional agriculture in Haryana supported a substantial breeding population of Woolly-necked Storks facilitated by agriculture-related components rather than existing natural features. This novel scenario contradicts conventional narratives that suggest multi-season small holder tropical and sub-tropical agriculture degrades breeding conditions for waterbirds. Our findings in Haryana reiterate the need to assemble a diverse conservation toolkit of different locally relevant mechanisms supporting biodiversity amid cultivation.
Crowded agricultural landscapes of the tropics and subtropics are assumed to be responsible for the decline of many waterbird species. This includes Woollynecked Storks, one of the least studied large waterbirds, with no longterm multiscale information on its ecology. In this study we provide densities, population size, flock size and habitat use of the species in agricultural landscapes across seven districts in lowland Nepal and India using the largest available field data set of Woollynecked Stork observations (N = 8,906 individuals in 3,133 flocks observed seasonally between 2014 and 2019). With this data, we asked whether these metrics showed variation by season and location. Woollynecked Stork densities fluctuated considerably, both with season in each location and across locations. Estimated population of Woollynecked Storks in the study area was 1,689 ± 922 (SD) which extrapolated to the known distribution range of the species in south Asia provided a coarse population estimate of 2,38,685 ± 1,24,471 (SD). Woollynecked Storks were seen mostly in small flocks of 14 birds (86% of flocks) with few extraordinarily large flocks. Flocks were significantly larger in Jhajjar and Kheda districts, in winter, and in fallow fields and wetlands. Most Woollynecked Storks were observed in agriculture fields (64% of 1,874 observations) with much fewer in wetlands (9%). In three locations where seasonal habitat use was measured, Woollynecked Storks varied habitat use seasonally in all locations. Of six locations where habitat preference was assessed, storks preferred wetlands in five locations. Results of this study suggest that the largest known global population of this species is resident in agricultural landscapes, and coarse population estimates suggests that the population size of this species was previously underestimated. Results also showed considerable variations in flock size and habitat use with location and season suggesting that Woolly necked Storks show plasticity in response to changing conditions on agricultural landscapes. These findings will be helpful to revise the species' status assessment and understanding its conservation requirements.
Provides a detailed background to the conservation status and ecological understanding available on Woolly-necked Storks, and showcases the value of replacing assumptions with field data. Underscores some incorrect assumptions regarding the conservation needs of the species, provides an update (with references from the Special Section of the same issue, and additional references), and provides a roadmap for improving the understanding of this species.
Top‐predators, including birds of prey, play an important role in ecosystems and are good bioindicators (Sergio et al. 2005). Links between the presence of predators and the overall biodiversity of a particular habitat mainly focus on trophic relationships (Roth and Weber 2008, Sergio et al. 2008b, Burgas et al. 2014). However, top‐predators not only have food requirements, but also need to build large, safe nests (Danko 2007). The building and occupancy of such nests by birds of prey are of the greatest importance for several reasons. The nests are often used for many years, due to the huge costs in time and energy of their construction, that, at least theoretically, offer possibilities of their use by many other animals for feeding, roosting and as breeding sites (Konrad and Gilmer 1982, Jiménez‐Franco et al. 2014).
Background:
Non-native species are often introduced in cities, where they take advantage of microclimatic conditions, resources provided by humans, and competitor/predator release to establish and proliferate. However, native communities in the surrounding rural or natural areas usually halt their spread through biotic resistance, mainly via top-down regulative processes (predation pressure). Here, we show an unusual commensal interaction between exotic and native bird species that favours the spread of the former from urban to rural habitats.
Results:
We show how Monk parakeets Myiopsitta monachus, an invasive species often introduced in cities worldwide, associated for breeding with a much larger, native species (the white stork Ciconia ciconia) to reduce predation risk in central Spain, thus allowing their colonization of rural areas. Parakeets selected stork nests close to conspecifics and where breeding raptors were less abundant. Parakeets always flushed when raptors approached their nests when breeding alone, but stayed at their nests when breeding in association with storks. Moreover, when storks abandoned a nest, parakeets abandoned it in the following year, suggesting that storks actually confer protection against predators.
Conclusions:
Our results show how a protective-nesting association between invasive and native species can counteract biotic resistance to allow the spread of an invasive species across non-urban habitats, where they may become crop pests. Monk parakeet populations are now growing exponentially in several cities in several Mediterranean countries, where they coexist with white storks. Therefore, management plans should consider this risk of spread into rural areas and favour native predators as potential biological controllers.
For a total of 9years, we examined the patterns of a nesting raptor community that utilized European Magpie (Pica pica) nests in the Zuojia Natural Reserve, northeast China. Eight raptor species and two other bird species were recorded nesting in magpie nests. The reuse rate of abandoned magpie nests was 51.6%, and the number of reused nests was positively correlated with their availability. Raptors utilized 83.3% of the reused abandoned magpie nests. Nests followed for more than 1year were reused by raptors an average of 1.13 times. Interspecific nest usurpation was common, with 17.3% of new magpie nests being usurped by raptors, and four cases of usurpation occurred among different raptor species. At the community level, 8 of 11 raptor species took over magpie nests to breed in the study area, and 91.9% of their nests came from magpie nests. European Magpies represent the core species in the nest web of the local raptor community that utilizes magpie nests. At the forest stand level, closer proximity to forest edges and greater distances from occupied raptor nests were the best predictors of nest reuse. At the nest-site level, arbor density and canopy coverage were the best predictors of nest reuse.
India, a mega-diverse country in terms of both biodiversity and people, is battling environmental problems on many fronts: chronic dependence on natural resources, dwindling ecosystem services, declining environmental quality, effects of climate change and a biodiversity crisis.
We review the current focal areas and infrastructure for ecological research and education in India, along with the surrounding legal and policy aspects of related socio-economic issues.
Currently, ecological and applied research is predominantly focused on charismatic species within protected areas. This scope could be broadened beyond organismal biology towards functional landscapes and ecosystems; the education system also needs to promote ecology as a career choice for scientists. Expectedly, many environmental challenges are generic in nature, occur in other regions of the world, are primarily biophysical in origin but extend into human dimensions; some challenges are socio-political and have implications for biodiversity conservation.
Synthesis and applications. India's environmental concerns include, but are not restricted to, the biodiversity crisis. The biodiversity crisis, in turn, includes, but is not restricted to, the most charismatic species. Greater integration and alignment among the mandates of government agencies, scientists, policymakers and educators are needed to meet contemporary environmental issues.
The practical analysis of space use and habitat selection by animals is often a problem due to the lack of well-designed programs. I present here the “adehabitat” package for the R software, which offers basic GIS (Geographic Information System) functions, methods to analyze radio-tracking data and habitat selection by wildlife, and interfaces with other R packages. These tools can be downloaded freely on the internet. Because the functions of this package can be combined with other functions of R, “adehabitat” provides a powerful environment for the analysis of the space and habitat use.
Cuckoos (family Cuculidae) show the highest diversity of breeding strategies within one bird family (parental care, facultative and obligate brood parasites). We used independent contrasts from two phylogenies to examine how this variation was related to 13 ecological and life-history variables. The ancestral state was probably tropical, resident, forest cuckoos with parental care. The evolution of brood parasitism was correlated with a shift to more open habitats, a change in diet, increases in species breeding-range size and migration, and a decrease in egg size. Once parasitism had evolved, more elaborate parasitic strategies (more harmful to host fitness) were correlated with decreased egg size, a change in diet, increased breeding-range size and migration, a shortened breeding season and a decrease in local abundance. Establishing the most probable evolutionary pathways, using the method of Pagel, shows that changes in ecological variables (such as migration, range size and diet type) preceded the evolution of brood parasitism, which is likely to be a later adaptation to reduce the cost of reproduction. By contrast, brood parasitism evolved before changes in egg size occurred, indicating that egg size is an adaptive trait in host--parasite coevolution. Our results suggest that the evolution of cuckoo brood parasitism reflects selection from both ecological pressures and host defences.
As with many farmland bird species, the house sparrow Passer domesticus is declining in Europe, mainly due to intensification of agriculture reducing nest sites and food supplies. During 2002-2005, we studied the population size and nest site characteristics of house sparrows breeding within white stork Ciconia ciconia nests in a large area of agricultural landscape within western Poland. To explain sparrow density within stork nests, we examined characteristics of white stork nests (position, age, productivity) and the farm type around the nest. House sparrow density was greatest in the longest established (and hence larger) white stork nests located on traditionally managed farms. Two recent changes appear to have adverse effects on house sparrows. The first is the intensification of farming and the second is active management of white stork nests on electric poles to reduce nest size and thus avoid both disruption to the electrical supply and electrocution of white storks. Because the white stork has such a high profile in Poland, there are numerous schemes to conserve and enhance this species. In conclusion, we clearly show that protecting one species can have valuable, although unplanned, benefits to another species of conservation interest, the house sparrow.
Given the serious limitations of production-oriented frameworks, we offer here a new conceptual framework for how to analyze the nexus of food security and biodiversity conservation. We introduce four archetypes of social-ecological system states corresponding to win-win (e.g., agroecology), win-lose (e.g., intensive agriculture), lose-win (e.g., fortress conservation), and lose-lose (e.g., degraded landscapes) outcomes for food security and biodiversity conservation. Each archetype is shaped by characteristic external drivers, exhibits characteristic internal social-ecological features, and has characteristic feedbacks that maintain it. This framework shifts the emphasis from focusing on production only to considering social-ecological dynamics, and enables comparison among landscapes. Moreover, examining drivers and feedbacks facilitates the analysis of possible transitions between system states (e.g., from a lose-lose outcome to a more preferred outcome).
PARASITIC cuckoos habitually lay their eggs in the nests of one or more host species. Because changes in one member of a hostparasite pair select for changes in the other member, it has been suggested that there is a revolutionary arms race between cuckoos and their hosts1-6. Comparisons of host species with species unsuitable as hosts, and the finding of host species from allopatric populations that tolerate nonmimetic eggs better than do species from sympatric populations, indicates that host behaviour has evolved in response to the behaviour of cuckoos5. Similarly, the observations that the laying procedure of cuckoos matches host defences2, and that cuckoo egg mimicry parallels the discriminatory ability of the host species7, indicates that cuckoo behaviour has evolved in response to host counter-adaptations. Here we demonstrate that rejection of eggs of the parasitic great spotted cuckoo Clamator glandarius by the magpie Pica pica hosts varies between populations depending on cuckoo parasitism. In a population of ancient sympatry, magpies reject both nonmimetic and mimetic eggs; in an area of recent sympatry magpies show less rejection, particularly of mimetic eggs; in a population isolated from great spotted cuckoos, however, magpies show no rejection. Such differences in egg recognition among host populations affect the spatial population dynamics of parasites and their hosts. Parasitic cuckoos therefore are in a particularly favourable position in the coevolutionary arms race with their hosts in areas of recent sympatry.
Biodiversity persistence in non-woody tropical farmlands is poorly explored, and multi-species assessments with robust landscape-scale designs are sparse. Modeled species occupancy in agricultural mosaics is affected by multiple factors including survey methods (convenience-based versus systematic), landscape-scale agriculture-related variables, and extent of remnant habitat. Changes in seasonal crops can additionally alter landscape and habitat conditions thereby influencing species occupancy. We investigated how these factors affect modeled occupancy of 56 resident bird species using a landscape-scale multi-season occupancy framework across 24 intensively cultivated and human-dominated districts in Uttar Pradesh state, north India. Convenience-based roadside observations provided considerable differences in occupancy estimates and associations with remnant habitat and intensity of cultivation relative to systematic transect counts, and appeared to bias results to roadside conditions. Modeled occupancy of only open-area species improved with increasing intensity of cultivation, while remnant habitat improved modeled occupancy of scrubland, wetland and woodland species. Strong seasonal differences in occupancy were apparent for most species across all habitat guilds. Further habitat loss will be most detrimental to resident scrubland, wetland and woodland species. Uttar Pradesh’s agricultural landscape has a high conservation value, but will require a landscape-level approach to maintain the observed high species richness. Obtaining ecological information from unexplored landscapes using robust landscape-scale surveys offers substantial advantages to understand factors affecting species occupancy, and is necessary for efficient conservation planning.
Performance analysis and companion functions for binary classification models. Package "InformationValue
- S Prabhakaran
Prabhakaran, S. (2016). Performance analysis and companion functions for
binary classification models. Package "InformationValue", v. 1.2.3.
Retrieved from http://r-stati stics.co/Infor matio n-Value -With-R.html
Aspects of the ecology of African Woolly-necked Storks (Ciconia microscelis) in an anthropogenic changing landscape in
- V Thabethe
Thabethe, V. (2018). Aspects of the ecology of African Woolly-necked
Storks (Ciconia microscelis) in an anthropogenic changing landscape
in KwaZulu-Natal, South Africa. Unpublished thesis, School of
Life Sciences, College of Agriculture, Science and Engineering,
University of KwaZulu-Natal, Pietermaritzburg Campus.
Aspects of the ecology of African Woolly‐necked Storks (Ciconia microscelis) in an anthropogenic changing landscape in KwaZulu‐Natal, South Africa
- V. Thabethe