CHILDREN OF THE NIGHT
Bat diversity and abundance are highest in old deciduous forest stands on the river banks in Eastern Ukraine
IMAGE: OLD FORESTS AND RIVERINE HABITATS IN EASTERN UKRAINE view more
CREDIT: PHOTO BY YEHOR YATSIUK
European forest-dwelling bats require complex woodland structures at both the micro-habitat and the landscape level for successful breeding in summer. Particularly, the results from Kharkiv region (Eastern Ukraine) demonstrate that large stands of mature forests older than 90 years improved the breeding activity of bats, their abundance and overall species richness. Abundance and species richness increased from upland plots surrounded by agricultural lands to riverine or waterside plots with high forest cover. These are the results of a newly published paper in the scientific journal “Forests” by an international team of authors from the Ukrainian Bat Rehabilitation Center (UBRC) and the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW).
Mature deciduous forests are the most targeted forest type for logging because of the high potential revenues from selling timber on international markets. Biodiversity associated with these forest stands is therefore threatened worldwide. One group of species that is a key conservation target are bats. In their investigation the scientific team around first author Dr Anton Vlaschenko from UBRC and Dr Viktoriia Radchuk from Leibniz-IZW asked how bat diversity is affected by land cover types and the age of forest stands in the Kharkiv region in northeastern Ukraine, in an area on the border between forest-steppe and the steppe zone. The fragmented broadleaved forests typical for this region are common for temperate regions, but the relationships between bat diversity, land cover and forest structure remain largely understudied. Yet, understanding such relationships is of key importance for designing efficient conservation measures.
The results showed that logging intensity in the study region differed between districts and was not related to the amount of mature forests. This allowed the scientists to study how bat assemblages were influenced by the share of clear-cuts and mature forests in the landscape. “The most conspicuous result was a clear increase of bat diversity close to riverine habitats, further enhanced by the presence of mature forests with a mean age more than 90 years”, says co-author Dr Yehor Yatsiuk from the University of Tartu (Estonia). “Although old forests represent 22% of all forests in the Kharkiv region, the combination of mature oak forests and riverine habitats covers much smaller areas, considerably limiting areas suitable for bats.”
First author Anton Vlaschenko, Co-Head of UBRC, says: “The field data used in this study were collected over a long period, in more than ten years of summer field expeditions. It was a continuous effort and hard job. We camped in tents and spent hundreds of sleepless nights near mist-nets. Later on, we also had some challenges when analysing these data. We were close to wrapping up the manuscript at the end of 2021. The collaboration with Leibniz-IZW scientists and, after February 24, 2022, the three-months scholarship for me and our team members offered by Leibniz-IZW meant that we could finish this paper.”
“The first time I participated to the field research studying bats in 2009, as an undergraduate student. The data collected back then contributed to the current paper. Since then, bats have become my big passion and focus group for my current research. By investigating the ecological requirements of such enigmatic animals, we better understand ecological leverages of the natural world”, adds co-author Dr Kseniia Kravchenko from UBRC and Leibniz-IZW. Dr Yehor Yatsiuk continues: “My research is focused on associations between historical distribution of forests and management of animal species in eastern Ukraine. Over recent decades we observed an increase in clear-cutting intensity in this region. Our aim is to ensure protection of forest biodiversity here. Ten years ago, we initiated a series of projects aimed to survey the oldest and the largest forests here with the main focus on several groups of vulnerable species from land snails to birds of prey and bats.”
“Our study shows that old forests and riverine habitats are beneficial for breeding activity of bats, for abundance of single bat species and for the overall community composition. The fact that we see the same response to landscape structure across levels of ecological organisation underlines the importance of preserving mature oak stands and riverine habitats for conservation of bat diversity in the region. I enjoyed working with Kharkiv bat researchers a lot, their enthusiasm and group spirit inspired me”, adds senior author Dr Viktoriia Radchuk, scientist at the Leibniz-IZW Department of Ecological Dynamics.
JOURNAL
Forests
METHOD OF RESEARCH
Case study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Bat Assemblages Are Shaped by Land Cover Types and Forest Age: A Case Study from Eastern Ukraine
Evolution of bat wings and calls through 'foraging syndromes' allows diversity to flourish
Study shows that echolocation frequency and wing shape of bats evolve in unison, which leads to distinct ‘foraging syndromes’ adapted to different environments
Peer-Reviewed PublicationBats are an evolutionary success story. With approximately 1,400 species living today, they thrive in every environment except the polar regions. They come in a remarkable range of sizes, from the golden-crowned flying fox with a mass of 1.2 kg and a wingspan of 171 cm, to Kitti's hog-nosed ‘bumblebee’ bat with a mass of 2 g and a wingspan of 33 cm. The frequencies that all bats emit during echolocation are also highly variable, ranging from 11 kHz to 212 kHz. But what has driven the evolution of this extraordinary diversity?
“Here we show with that among bat species, there is a close correspondence between wing shape and the frequency of their echolocation vocalizations. This pattern wasn’t found in earlier studies because it’s hidden among the variation due to family,” said Dr Bo Luo, a researcher at China West Normal University and a corresponding author on the study, which is published in Frontiers in Ecology and Evolution.
“And importantly, both are tightly linked to foraging ecology – the preferred habitat type of a species and how it catches prey there.”
Evolutionary trade-offs
Scientists already knew that different wing shapes are optimal for bats in certain environments: for example, short, round wings are more maneuverable in confined spaces, while long, pointed wings are best for fast flight over long distances. Echolocation also requires trade-offs: calls with long duration or high frequency are more costly to produce, but are more effective at detecting tiny prey among environmental clutter. So how are these competing demands balanced?
Luo and colleagues gathered published data on 152 species of bats in 15 families: each species’ body mass, the duration and peak frequency of its echolocation calls, the body mass divided by the wing area (‘wing loading’) and the wing ‘aspect ratio’ – the square of the wingspan divided by wing area. As a proxy for ecology, they assigned each species to one of five ‘foraging guilds’. For example, edge-space trawling foragers scoop up insects or small fish from water surfaces with their tail membrane and feet, while open-space aerial foragers catch insects on the wing in the open air.
Strong effect of family
The authors found that echolocation peak frequency and wing morphology are strongly dependent on bat family. This means that any other evolutionary patterns are likely to remain hidden, unless the range of families and species in the sample is large. And it’s the large sample of the present study which revealed that after differences between families are taken into account, peak frequency in echolocation and wing shape tend to be positively associated with each other.
Corresponding author Dr Jiang Feng, a professor at Northeast Normal University, said: “Our results show that peak frequency and wing shape are linked: for example, bat species that hunt in open spaces tend to have long, pointed wings, and to produce long echolocation calls of low frequency.”
“In contrast, species that hunt in edge spaces tend to have short, round wings, and to emit short calls of intermediate frequency. And species that forage in narrow spaces tend to have short, round wings and high-frequency calls.”
Distinct foraging syndromes
The authors concluded that echolocation parameters and wing shape haven’t evolved independently from each other. Rather, they both evolved as dictated by each species’ foraging ecology. For each type of habitat, there is a unique optimal evolutionary solution – a foraging syndrome – that matches wing shape and echolocation traits to foraging mode. These syndromes have evolved repeatedly in each family.
“We demonstrate that foraging ecology drives the correlated evolution of wing morphology and echolocation calls in extant bats. This doesn’t necessarily mean that flight and echolocation evolved simultaneously. To answer the question of which came first, we need research that explores similarities in forelimb shape, the auditory system, and associated traits between extant bats and fossils of bat progenitors,” said Luo.
JOURNAL
Frontiers in Ecology and Evolution
METHOD OF RESEARCH
Data/statistical analysis
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Correlated evolution of wing morphology and echolocation calls in bats
ARTICLE PUBLICATION DATE
9-Dec-2022
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