The Diet of a Roosting Population of Asian Glossy Starling Aplonis panayensis in Jelebu, Negeri Sembilan, Malaysia

Communal roosting by urban birds, such as crows, mynas, and starlings, can be a public nuisance due to excessive noise and fouling of the surroundings with droppings. Food availability within proximity to the roosting area is one of the key factors influencing roosting site preference and fidelity. The diets of roosting mynas and crows have been well-studied, yet little is known about the diet of the Asian glossy starling (AGS), Aplonis panayensis. This study focused on assessing the diet of roosting AGS and food resource availability around the roosting area. The AGS diet was assessed through microscopic analysis of stomach contents and droppings. The diet mainly consisted of fruits (76%) with a minor component of animal materials, i.e. ants, snails, and beetle larvae. Intact seeds found in the samples were identified using DNA barcoding. Seven out of the nine plant species detected were new records for the AGS diet. The most common fruit found in the samples was Trema orientalis, which grows extensively along roadsides within foraging areas of AGS. The availability of fruits of different fast-growing pioneer species around the roosting site ensured a continuous supply of food to the birds. Animal materials, which were consumed by chance during foraging, supplemented the fruit in the bird’s diet. Hence, the birds’ preference for the roosting site may have been influenced by the availability of various food resources around it.

Mixed-species groups in bats: non-random roost associations and roost selection in neotropical understory bats

Background Mixed-species groups in animals have been shown to confer antipredator, foraging and other benefits to their members that may provide selective advantages. In most cases, however, it is unclear whether functional benefits are a principal driver of heterospecific groups, or whether groups simply result from simultaneous exploitation of common resources. Mixed-species groups that form independently of environmental conditions may, however, evidence direct benefits of species associations. Bats are among the most gregarious mammals, with sometimes thousands of individuals of various species roosting communally. Despite numerous potential functional benefits of such mixed-species roosting groups, interspecific attraction has never been shown. To explore alternative explanations for mixed-species roosting, we studied roost selection in a speciose neotropical understory bat community in lowland rainforest in Costa Rica. Long term roost data were recorded over 10 years in a total of 133 roosts comprising both natural roosts and structurally uniform artificial roosts. We modelled bat roost occupancy and abundance in each roost type and in forest and pasture habitats to quantify the effects of roost- and environmental variability. Results We found that bat species presence in natural roosts is predictable from habitat and structural roost parameters, but that the presence and abundance of other bat species further modifies roost choice. One third of the 12 study species were found to actively associate with selected other bat species in roosts (e.g. Glossophaga commissarisi with Carollia sowelli). Other species did not engage in communal roosting, which in some cases indicates a role for negative interspecific interactions, such as roost competition. Conclusions Mixed-species roosting may provide thermoregulatory benefits, reduce intraspecific competition and promote interspecific information transfer, and hence some heterospecific associations may be selected for in bats. Overall, our study contributes to an improved understanding of the array of factors that shape diverse tropical bat communities and drive the dynamics of heterospecific grouping in mammals more generally.

On the record of Calomera funerea funerea (MacLeay, 1825) (Coleoptera: Cicindelidae) from Odisha, Eastern India

Calomera funerea funerea is reported for the first time from Odisha, Eastern India, represents southernmost locality of the subspecies. Among the two Indian subspecies of Calomera funerea, Calomera f. funerea was previously known from Northern and North-eastern India. On 1.ix.2015, more than 100 individuals of Calomera f. funerea were observed along with a Calomera angulata, in a communal roosting, at Balikiari Reserve Forest of Athgarh Forest Division, Odihsa, India.

Diet of the lesser kestrel Falco naumanni at post-breeding roosts in southern Albania

The lesser kestrel is an insectivorous and migratory falcon species, frequently using communal roosts in the post-breeding period in southern Europe. Using pellet analysis from two post-breeding roosting sites in southern Albania collected in August 2017, we identified 1539 prey items belonging to approximately 58 prey species, 20 families and 7 orders in 110 pellets from two sites. Invertebrates made up the major part of the diet spectrum (PNI = 99.8 %, PFI = 100 %). Invertebrate prey body size varied between 8 and 62 mm (mean 28.1 mm). Bush-crickets (Tettigoniidae) and locusts (Acrididae) were the most abundant and frequent prey groups (PNI = 33 % resp. 48.6 % and PFI = 97 % resp. 94 %). Within the bush-cricket family we could identify the species of genera Tettigonia, Decticus, Platycleis, Isophya and Metrioptera. The species of genera Calliptamus, Stenobothrus and Locusta belonged among the locust species identified in the food. Birds and mammals were found in pellets only occasionally. The prey composition was rather similar at both studied sites, while locusts (Acrididae) were more abundant at the Jorgucat site and bush-crickets (Tettigonioidea) at the Mollas site in the same time. Prey groups Scarabeidae beetles and other beetles (Coleoptera other) were more abundant and frequent at Mollas than at Jorgucat, and spiders were more frequent at Jorgucat. These results suggest that the high abundance of orthopterans and beetles in the food supply in certain localities is the main reason for selection and stable occupancy of these massive communal roosting sites by lesser kestrels in Albania.

Communal roosting of Egyptian vulture Neophron percnopterus in Uttar Pradesh, India

The behaviour of birds to settle or rest at a place at specific times of day and night is called roosting. Some birds prefer solitary roosting while others roost communally. The Communal roosting behaviour of Egyptian vulture was studied in five districts (Sambhal, Lakhimpur Kheri, Aligarh, Bareilly and Faizabad) of Uttar Pradesh, India from January 2014- December 2017. Total count was conducted at roosting sites in all the seasons (summer, winter and monsoon). The maximum number of individuals counted at the roost site was in Sambhal followed by Lakhimpur Kheri, Aligarh, Bareilly, Faizabad. Four different roost substrates were identified: Ground, tree, building, and electric pylon. A maximum (63%) of Egyptian vultures were observed roosting on the ground, followed by electric pylon (19%), tree (10%) and minimum on building (8%). The present study confirmed that Egyptian vultures are communal roosters and a number of roosting individuals most probably depended on the availability of food of the area. Egyptian vultures are globally endangered species and so far no work has been done on their roosting behaviour in India; therefore the present study will prove beneficial to plan for their conservation strategies.

Notes on a communal roosting of two oakblues (Lepidoptera: Lycaenidae: Arhopala) and the Common Emigrant (Pieridae: Catopsilia pomona) butterflies in Uttarakhand, India

Communal roosting on an over-nightly basis is common in butterflies for resting and for avoiding predation. Having a source of nectar and safeguarding from harsh weather conditions are also notable parameters to consider a site as a potential roosting spot. Roosting differs from a congregation in the fact that the latter happens mainly in the exposed plant part or the oozing out of fluid, which attracts the butterflies to extract chemicals from the same. The current study has been conducted on an Elephant-apple tree Dillenia indica in the New Forest campus of Dehradun, Uttarakhand, India to observe the roosting behaviour of three blue butterfly species, namely: Large Oakblue Arhopala amantes, Indian Oakblue Arhopala atrax, and pierid butterfly Common Emigrant Catopsilia pomona. The roosting observation was first noted during mid-October. The coinciding of the roosting period and the fruiting season of the tree may mark the importance of having a food source in a potent roosting site. Moreover, the site would provide a shady area with dense foliage, which would also include safeguards against predation.

Sleeping on a tightrope: White-breasted Cormorants Phalacrocorax lucidus and African Darters Anhinga rufa roosting on transmission lines

Though recent research has explored the negative impact of human infrastructure on large waterbirds, few studies have examined behavioural byproducts such as roosting or nesting on transmission wires. Here, we document our observation of a joint roost of White-breasted Cormorant Phalacrocorax lucidus and African Darter Anhinga rufa on transmission lines in the Western Cape, South Africa. We highlight current gaps in understanding communal roosting, joint roosts between species, and roosting on infrastructure, and provide recommendations for future directions of study.

Data-driven modeling of group formation in the fission-fusion dynamics of Bechstein’s bats

Communal roosting in Bechstein’s bat colonies is characterized by the formation of several groups that use different day roosts and that regularly dissolve and re-merge (fission-fusion dynamics). Analyzing data from two colonies of different size over many years, we find that (i) the number of days bats stay in the same roost before changing follows an exponential distribution that is independent of the colony size, and (ii) the number and size of groups bats formed for roosting depend on the size of the colony such that above a critical colony size two to six groups of different sizes are formed. To model these two observations, we propose an agent-based model in which agents make their decisions about roosts based on both random and social influences. For the latter, they copy the roost preference of another agent which models the transfer of the respective information. Our model is able to reproduce both the distribution of stay length in the same roost and the emergence of groups of different sizes dependent on the colony size. Moreover, we are able to predict the critical system size at which the formation of different groups emerges without global coordination. We further comment on dynamics that bridge the roosting decisions on short time scale (less than one day) with the social structures observed at long time scales (more than one year).

Data-driven modeling of leading-following behavior in Bechstein’s bats

Leading-following behaviour in Bechstein’s bats transfers information about suitable roost sites from experienced to inexperienced individuals, and thus ensures communal roosting. We analyze 9 empirical data sets about individualized leading-following (L/F) events, to infer rules that likely determine the formation of L/F pairs. To test these rules, we propose five models that differ regarding the empirical information taken into account to form L/F pairs: activity of a bat in exploring possible roosts, tendency to lead and to follow. The comparison with empirical data was done by constructing social networks from the observed L/F events, on which centralities were calculated to quantify the importance of individuals in these L/F networks. The centralities from the empirical network are then compared for statistical differences with the model-generated centralities obtained from 105 model realizations. We find that two models perform well in comparison with the empirical data: One model assumes an individual tendency to lead, but chooses followers at random. The other model assumes an individual tendency to follow and chooses leaders according to their overall activity. We note that neither individual preferences for specific individuals, nor other influences such as kinship or reciprocity, are taken into account to reproduce the empirical findings.