Bat activity in Ammarnäs, Västerbotten - Infuence of biological and environmental factors on the activity of Northern bats (Eptesicus nilssonii) in Northern Sweden
(2024) BION02 20232Degree Projects in Biology
- Abstract
- In northern Sweden, insectivorous bats must face challenging conditions throughout most of the year, with longer and colder winters compared to the south, and continuous daylight for several weeks during the summer. The northern bat (Eptesicus nilssonii) is common in Sweden, despite experiencing population declines over the last 30 years, and can be found at high latitudes across Europe. This study utilized acoustic monitoring from June to September to explore E. nilssonii activity across various habitats around Ammarnäs (Västerbotten), towards the northern limit of its range, and to assess the impact of weather parameters, insect abundance and diversity, and habitat characteristics on its activity. Bat activity showed positive... (More)
- In northern Sweden, insectivorous bats must face challenging conditions throughout most of the year, with longer and colder winters compared to the south, and continuous daylight for several weeks during the summer. The northern bat (Eptesicus nilssonii) is common in Sweden, despite experiencing population declines over the last 30 years, and can be found at high latitudes across Europe. This study utilized acoustic monitoring from June to September to explore E. nilssonii activity across various habitats around Ammarnäs (Västerbotten), towards the northern limit of its range, and to assess the impact of weather parameters, insect abundance and diversity, and habitat characteristics on its activity. Bat activity showed positive associations with temperature and daily precipitation, while light intensity in July affected activity levels outside the village. Insect abundance and diversity had a weak effect or no effect on bat activity. Distance to water did not affect activity levels, but bats were more active in human modified environments and close to houses, making them vulnerable to human disturbances. (Less)
- Popular Abstract
- Northern bat activity in Northern Sweden
In temperate regions, insectivorous bats must adapt to the seasonal fluctuations in environmental conditions and food resources. They use torpor for a significant part of the year, allowing them to minimize energy expenditures and endure long periods of cold and food scarcity. But torpor isn’t just a winter strategy. It can be used during summer on cold, windy, or rainy nights. At high latitudes, bats face an even tougher challenge due to shorter and colder summers, during which these nocturnal mammals must contend with a few weeks of continuous daylight.
Using a combination of active and passive acoustic monitoring of bats, the study aimed to investigate how northern bats (Eptesicus nilssonii)... (More) - Northern bat activity in Northern Sweden
In temperate regions, insectivorous bats must adapt to the seasonal fluctuations in environmental conditions and food resources. They use torpor for a significant part of the year, allowing them to minimize energy expenditures and endure long periods of cold and food scarcity. But torpor isn’t just a winter strategy. It can be used during summer on cold, windy, or rainy nights. At high latitudes, bats face an even tougher challenge due to shorter and colder summers, during which these nocturnal mammals must contend with a few weeks of continuous daylight.
Using a combination of active and passive acoustic monitoring of bats, the study aimed to investigate how northern bats (Eptesicus nilssonii) utilized the available habitats and adjusted their activity in response to weather conditions, light intensity, and variations in insect availability.
Bat activity fluctuates a lot from night to night depending on weather conditions. Adverse weather conditions such as low temperatures, wind, or rain will not only affect the activity of the insects bats rely on for sustenance, but they will also increase the amount of energy required for flight and foraging. In such conditions, bats will usually go without feeding, and use torpor instead to conserve energy. This study showed that northern bat activity decreased on cold nights and windy nights but bats were not less active on rainy nights. Surprisingly, bat activity was higher on days with some amount of rain. Bats appeared to be more active during weeks with high insect availability and insects might benefit from higher humidity levels and become more abundant following rainfall.
In early summer, bats were less active, with most activity concentrated within the village. Urban areas offer an abundance of roosting sites in buildings, where females can establish maternity colonies and rear their young. During lactation, females maintain an active presence around their roosts, making regular visits throughout the night to nurse their offspring. Moreover, heightened visibility to diurnal predators due to increased light intensity during this period prompts bats to reduce their activity and forage closer to their roosts to minimize predation risk. They maintain their nocturnal activity throughout this period and are only active for a short time, during the darkest part of the night.
By the beginning of August, bats became more active outside the village and used a variety of habitats. However, they showed a preference for urban areas throughout the summer. In September, when temperatures started to drop, bats were seen more often in the village. Northern bats can take advantage of the aggregation of insects around streetlights when they become scarce. During this period, bats also demonstrated heightened activity at higher altitudes, potentially in search of suitable hibernation sites. However, further research needs to be conducted to find out where they spend the winter to study their activity throughout the year.
In Northern Sweden, northern bats are very active in urban areas, which offer them roosting sites and foraging opportunities. It is thus important to consider how human activity may affect them.
Master’s Degree Project in Biology, 45 credits, 2024
Department of Biology, Lund University
Advisor: Martin Green
Department of Biology, Lund University (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9154593
- author
- Merlet, Maëla
- supervisor
-
- Martin Green LU
- organization
- course
- BION02 20232
- year
- 2024
- type
- H2 - Master's Degree (Two Years)
- subject
- language
- English
- id
- 9154593
- date added to LUP
- 2024-05-27 13:59:14
- date last changed
- 2024-05-27 13:59:14
@misc{9154593,
abstract = {{In northern Sweden, insectivorous bats must face challenging conditions throughout most of the year, with longer and colder winters compared to the south, and continuous daylight for several weeks during the summer. The northern bat (Eptesicus nilssonii) is common in Sweden, despite experiencing population declines over the last 30 years, and can be found at high latitudes across Europe. This study utilized acoustic monitoring from June to September to explore E. nilssonii activity across various habitats around Ammarnäs (Västerbotten), towards the northern limit of its range, and to assess the impact of weather parameters, insect abundance and diversity, and habitat characteristics on its activity. Bat activity showed positive associations with temperature and daily precipitation, while light intensity in July affected activity levels outside the village. Insect abundance and diversity had a weak effect or no effect on bat activity. Distance to water did not affect activity levels, but bats were more active in human modified environments and close to houses, making them vulnerable to human disturbances.}},
author = {{Merlet, Maëla}},
language = {{eng}},
note = {{Student Paper}},
title = {{Bat activity in Ammarnäs, Västerbotten - Infuence of biological and environmental factors on the activity of Northern bats (Eptesicus nilssonii) in Northern Sweden}},
year = {{2024}},
}