Movement ecology, breeding, diet and roosting behavior of barn owls (Tyto alba) in a transboundary conflict region

Transboundary frontiers often contain wildlife habitats that are fractured by geopolitical borders, which could have adverse effects on the wildlife that inhabit those areas. We examined the movement, breeding, roosting and diet of 15 GPS-tagged barn owls (Tyto alba) along the Israeli-Jordanian and Israeli-Palestinian Authority borders. Our results showed that 80% of the barn owls hunted across the border. On average, the owls engaged in 5.4 hunting trips per night, 16% of which were cross-border excursions, and they crossed the borders as frequently as expected randomly, highlighting the importance of wildlife protection on all sides. Hunting movement, rather than cross-border activity, had an effect on the annual reproductive success and diet composition. Specifically, female owls that spent more time at the nest and engaged in longer distance hunting trips had higher reproductive success. 80% of the females roosted outside of the nest box at a median distance of 908 m (range = 199 - 4,112 m). Only 13.3% of the owls (2/15 owls) roosted across the border. These results increase our understanding of the movement, breeding, and roosting behavior of a non-migratory avian raptor. However, a serious lack of cooperation and communication between bordering countries hampers our ability to understand the full effects of differing environmental policies on a species that knows no borders.

Quantifying individual influence in leading-following behavior of Bechstein’s bats

Leading-following behavior as a way of transferring information about the location of resources is wide-spread in many animal societies. It represents active information transfer that allows a given social species to reach collective decisions in the presence of limited information. Although leading-following behavior has received much scientific interest in the form of field studies, there is a need for systematic methods to quantify and study the individual contributions in this information transfer, which would eventually lead us to hypotheses about the individual mechanisms underlying this behaviour. In this paper we propose a general methodology that allows us to (a) infer individual leading-following behaviour from discrete observational data and (b) quantify individual influence based on methods from social network analysis. To demonstrate our methodology, we analyze longitudinal data of the roosting behavior of two different colonies of Bechstein’s bats in different years. Regarding (a) we show how the inference of leading-following events can be calibrated from data making it a general approach when only discrete observations are available. This allows us to address (b) by constructing social networks in which nodes represent individual bats and directed and weighted links—the leading-following events. We then show how social network theory can be used to define and quantify individual influence in a way that reflects the dynamics of the specific social network. We find that individuals can be consistently ranked regarding their influence in the information transfer. Moreover, we identify a small set of individuals that play a central role in leading other bats to roosts. In the case of Bechstein’s bats this finding can direct future studies on the individual-level mechanisms that result in such collective pattern. More generally, we posit that our data-driven methodology can be used to quantify leading-following behavior and individual impact in other animal systems, solely based on discrete observational data.

The Ecology of Nipah Virus in Bangladesh: A Nexus of Land-Use Change and Opportunistic Feeding Behavior in Bats

Nipah virus is a bat-borne paramyxovirus that produces yearly outbreaks of fatal encephalitis in Bangladesh. Understanding the ecological conditions that lead to spillover from bats to humans can assist in designing effective interventions. To investigate the current and historical processes that drive Nipah spillover in Bangladesh, we analyzed the relationship among spillover events and climatic conditions, the spatial distribution and size of Pteropus medius roosts, and patterns of land-use change in Bangladesh over the last 300 years. We found that 53% of annual variation in winter spillovers is explained by winter temperature, which may affect bat behavior, physiology, and human risk behaviors. We infer from changes in forest cover that a progressive shift in bat roosting behavior occurred over hundreds of years, producing the current system where a majority of P. medius populations are small (median of 150 bats), occupy roost sites for 10 years or more, live in areas of high human population density, and opportunistically feed on cultivated food resources—conditions that promote viral spillover. Without interventions, continuing anthropogenic pressure on bat populations similar to what has occurred in Bangladesh could result in more regular spillovers of other bat viruses, including Hendra and Ebola viruses.

Adult Desert Locust Swarms, Schistocerca gregaria, Preferentially Roost in the Tallest Plants at Any Given Site in the Sahara Desert

The desert locust, Schistocerca gregaria, is a major migratory pest that causes substantial agricultural damage. Flying adult swarms disperse widely during the daytime, but they densely roost on plants at night. Swarm control operations are generally conducted during the daytime, but night-time control is a significant potential alternative. However, the night-roosting behavior of swarms is poorly understood. We determined night-roosting plant preferences of migrating sexually immature swarms of S. gregaria at four different sites in the Sahara Desert in Mauritania during winter. The night-roosting sites were divided into two types based on presence or absence of large trees. Swarms tended to roost on the largest trees and bushes at a given site. Swarms used medium-sized plants when large trees were not locally available, but the same medium-sized plant species were hardly used when large trees were available. Plant choice influenced roosting group size—large locust groups roosted on larger plants. Night-roosting locusts rarely fled from approaching observers. These results suggest that swarms of S. gregaria exhibit plasticity in their utilization patterns of night-roosting plants depending on the plant community encountered and they selectively use larger plants. We propose that this predictable plant-size dependent night-roosting can be used to particularly ease locust swarm control and to generally adopt anti-locust night control strategy.

The ecology of Nipah virus in Bangladesh: a nexus of land use change and opportunistic feeding behavior in bats

Nipah virus is a bat-borne paramyxovirus that produces yearly outbreaks of fatal encephalitis in Bangladesh. Understanding the ecological conditions that lead to spillover from bats to humans can assist in designing effective interventions. To investigate the current and historical processes that drive Nipah spillover in Bangladesh, we analyzed the relationship between spillover events and climatic conditions, the spatial distribution and size of Pteropus medius roosts, and patterns of land use change in Bangladesh over the last 300 years. We found that 53% of annual variation in winter spillovers is explained by winter temperature, which may affect bat behavior, physiology, and human risk behaviors. We infer from changes in forest cover that a progressive shift in bat roosting behavior occurred over hundreds of years, producing the current system where a majority of P. medius populations are small (median of 150 bats), occupy roost sites for 10 years or more, live in areas of high human population density, and opportunistically feed on cultivated food resources – conditions that promote viral spillover. Without interventions, continuing anthropogenic pressure on bat populations similar to what has occurred in Bangladesh could result in more regular spillovers of other bat viruses, including Hendra and Ebola viruses.

Analysis of astrovirus transmission pathways in a free-ranging fission-fusion colony of Natterer’s bats (Myotis nattereri)

Bats are a diverse and widespread order of mammals. They fulfill critical ecosystem roles but may also act as reservoirs and spreaders for zoonotic agents. Consequently, many recent studies have focused on the potential of bats to spread diseases to other animals and to humans. However, virus transmission networks within bat colonies remain largely unexplored. We studied the detection rate and transmission pathway of astroviruses in a free-ranging Natterer’s bat colony (Myotis nattereri) that exhibits a high fission-fusion dynamic. Based on automatic roost monitoring data of radio-frequency identification tagged bats, we assessed the impact of the strength of an individual’s roosting associations with all other colony members (weighted degree), and the number of roost sites (bat boxes) an individual used—both being proxies for individual exposure risk—on the detected presence of astrovirus-related nucleic acid in individual swab samples. Moreover, we tested to which degree astrovirus sequence types were shared between individuals that frequently roosted together, as proxy for direct transmission risk, and between bats sharing the same roost sites in close temporal succession, as proxy for indirect transmission risk. Neither roosting associations nor the number of different roost sites had an effect on detected virus presence in individual bats. Transmission network data suggest that astroviruses are transmitted both via direct and indirect contact, implying that roost sites pose a risk of astrovirus infection for several days after the bats leave them. Our study offers novel insights in the presence and transmission of viruses within social networks of bat colonies. Significance statement Bats provide many ecosystem services but have moved into the focus of virological research as potential carriers of zoonotic disease agents. However, the sparse information available about virus transmission within bat colonies is solely based on simulated transmission data. In this field study, we examined the daily roosting behavior in a wild bat colony in relation to the presence of viruses in individual colony members. Our findings suggest that astroviruses are transmitted by direct contact and via contaminated roost sites. Bats typically defecate in their roost sites, and astroviruses can remain infectious in feces for several days. The here observed virus diversity and roosting behavior suggest that bats can contract astroviruses even if they use contaminated roost sites days after infected individuals have left. This study provides first-time insights in the transmission of astroviruses within bat colonies in the wild.

Short Communication: Roosting behavior of Wintering Barn Swallow (Hirundo rustica) in Peninsular Malaysia

Ismail NA, Jufri ABAK, Daud UNS, Nor SM, Mansor MS. 2020. Short Communication: Roosting behavior of Wintering Barn Swallow (Hirundo rustica) in Peninsular Malaysia. Biodiversitas 21: 661-665. The East Asian Barn Swallow Hirundo rustica gutturalis primarily breeds in China, Japan, and Korea, typically migrates to Southeast Asia during winter, including Malaysia. To date, knowledge regarding population of Barn Swallow are limited to their breeding grounds and other subspecies (e.g., European Barn Swallow Hirundo rustica rustica). A previous study on Barn Swallow wintering in Malaysia was conducted approximately 50 years ago and mainly focused on population dynamics. The objective of the present study was to investigate the roosting behavior of wintering Barn Swallows in a major roosting site, Bentong, central Peninsular Malaysia, from October 2018 to March 2019. Scan sampling at 5-min intervals was used to examine the roosting behavior of the swallows perching on service wires (i.e., electricity and telephone wires). We found that the swallows began to roost an average of 10 minutes after sunset and slept 55 minutes later. However, cloudy and rainy weather significantly affects swallow roosting period, leading them to perch earlier, 5 minutes before sunset. The pattern of roosting behavior was somewhat similar throughout the migration season, except in the early migration season (October), which was likely inconsistent due to their early adaptation to the town environment. Behavioral scan sampling revealed that swallows spend most of the time motionless, followed by preening. However, anthropogenic disturbances disrupt their behavior and sleep time. We also noted that this communally roosting bird behaved gregariously on wires, particularly at sites illuminated by light, which is likely an anti-predator mechanism.

First record on the roosting behaviour of Montane myotis Myotis oxyotus (Chiroptera: Vespertilionidae)

Montane myotis is an Andean bat species whose ecology and roosting behavior is poorly known. Three females were discovered and caught roosting in a crevice in a home’s roof located in Sibundoy Valley (SW Colombia). This is the first roost of Montane myotis ever recorded and evidence that this species, usually caught in forests, may use anthropogenic shelters.