Habitat fragmentation can profoundly disrupt the community dynamics in an ecosystem. Within similar habitats, species still face unique threats caused by fragmentation. To complicate things further, individuals of the same species often have differing needs within their landscapes.
Intraspecific variation (variation within a species) can be difficult to account for since conservation policy and research often focus on the species level. One form of intraspecific variation is sexual segregation. In some species, male and female individuals respond differently to landscape features and group together by sex. This can alter the population sex ratio of a given area.
Fialas, P.C., Gilmour, L.R., Vickress, S., Underwood, E., Williams, C.A., Miller, H. and Lintott, P.R. 2022. Sexual segregation occurs in bats within fragmented remnant woodlands in an agricultural landscape. Ecology and Evolution 12(10): e9350.
Many bats exhibit sex differences in migration, foraging, and roost selection. Since many bats are reliant on woodlands for these behaviors, they are particularly impacted by poor forest connectivity. Because of their diversity, sensitivity to landscape change, and the critical ecosystem services they provide, bats can be indicator species for ecosystem health.
A recent study focused on sexual segregation in six bat species in fragmented woodland habitats in England. According to WWF-UK, the UK is 70% farmland, and the intensification of agriculture over the last several decades has been the biggest threat to wildlife there. Using data collected by citizen scientists, researchers sought to understand sex differences in how bats use habitat and respond to fragmentation. Almost nine hundred bats were captured and identified in over two hundred fragmented woodlands. Researchers compared the probability of capturing a female bat vs. a male bat in forest patches with varying connectivity and surrounding habitat quality.
One crucial takeaway was that the connectivity of patches, as well as the quality of the surrounding area, influenced the presence of female bats in remnant woodlands. When woodland patches were poorly connected and surrounded by agricultural land, female bats of three generalist species were constrained to woodland patches. In these cases, males were more likely to be found in agricultural grassland (lower quality habitat), possibly due to increased competition in the higher quality woodland habitats.
However, in woodlands with semi-natural surrounding habitat acting as a better foraging area, females were less likely to be found in the woods than in the surrounding grasslands. In that case, landscape factors (such as the agricultural history of surrounding area and the connectivity with other patches) had a much greater effect on sexual segregation than the quality of the woodland patches themselves, indicating that when it comes to fragmented habitat, what’s on the outside counts, too.
This research emphasizes the importance of a landscape level approach, considering not only the patches but the quality of the habitat surrounding them. Furthermore, each species demonstrated sexual segregation differently, and some not at all. In species where sexual segregation occurs, it should be considered in sampling, site prioritization, and land management. Where possible, a conservation approach should seek to understand how both differences between species and within species can amplify the effects of fragmentation.
Related Posts
Keeping rare species connected in urban areas
Plans to protect multiple rare species across a gradient of urban areas in Michigan provide a template for preserving biodiversity in an increasingly urban world.
Microbats benefit from a restored corridor in tropical northern Australia
Detections in a replanted forest corridor in Queensland show that while some bats may be sensitive to fragmentation, they can respond positively to the re-establishment of connectivity.
Habitat fragmentation and sexual segregation
Citizen science data on bats in England shows how males and females respond differently to woodland fragmentation and connectivity.
