Giving some information on our native flying mammals and tips on how to attract them to your doorstep.
Amidst the current global pandemic, bats have been in the news quite a bit with the acquired delicacy of bat soup as a possible source of the virus’ transmission to humans. This has led to a mixed bag of press for the flying mammals, with some sources calling them disgusting harbingers of disease to others giving a rightful amount of sympathy towards the creatures for finding their way into a broth. With the hope that the consumption of exotic animals such as bats can come to an end after the situation humanity finds itself in, I wanted to provide my own ethical smorgasbord of facts and information about Irelands own bat species, and even some steps on how to help these animals and encourage them to visit your garden.
As the weather gradually warms up and Spring begins to meet Summer, we can start to see bats flying around in our night skies once more. Bats in Ireland awake from their hibernation around April/May, depending on the weather and food supply at the time. They have been in their hibernacula, or hibernation roosts, since October/November. Bats alongside hedgehogs are the only Irish mammals to enter through hibernation, only waking during the winter months for the occasional drink of water. In this hibernation state the bats use very little energy, and their body temperature drops to 8-9°C. Bats may start slowly with their foraging of nocturnal insects but will continue hunting for longer as the nights warm up into the Summer.
Ireland has 9 species of bat hailing from two separate families. 8 of our species are from the Family Vespertilionidae which includes pipistrelles, whiskered bats and brown long eared bats. The other species, the lesser horseshoe bat, belongs to the Family Rhinolophidae. There are a couple of noticeable differences between these two families.
Vespertilionid bats have an uncomplicated muzzle and a flap of skin outside of the ear. This is called a tragus, and it helps the bat to determine the vertical position of prey during foraging. They also produce their echolocation calls through their mouths, by either contracting their larynx or clicking their tongue.
Whereas with Rhinolophid bats, they have a complicated muzzle with multiple flaps of skin called a noseleaf which forms a horseshoe around the nostrils. This allows them to focus their echolocation calls through their noses as they produce their calls from their nostrils.
All our species of bats are insectivores, meaning they only eat insects and insect larvae. There are no vampire or fruit bats in Ireland. In fact, out of the 45 species of bats in Europe there is only one species of fruit eating bat, the Egyptian fruit bat. All of Irelands bats are also very small, with an average weight of 5 grams.
Female bats begin to roost in early summer in nursery or maternal roosts, but few adult males will be present. Bats mate from August until hibernation and females will hold onto the sperm until conditions are right to ovulate, fertilise her egg and give birth. They will all then give birth to a single baby in these maternal roosts in late June/early July.
Due to a lot of help from different conservation bodies and voluntary efforts bat numbers have stabilised or steadily increased, but this follows a considerable decline throughout the past three centuries in Ireland. There are several organisations researching bat populations in Ireland, with Bat Conservation Ireland (there website is where I got a lot of my information for this article) carrying out a lot of monitoring projects on several species. Along with funding from the National Parks and Wildlife Service and the Northern Ireland Environment Agency and a lot of help from volunteers Bat Conservation Ireland have been able to track yearly trends since 2003 in three bats; the common pipistrelle, the soprano pipistrelle and Leisler’s bat. Other species are also being monitored in feeding and roosting sites.
Despite all the efforts from the peoples mentioned above, bats remain vulnerable at a local level due to threats such as water pollution, increased artificial night lighting, pesticides and hedgerow loss but to name a few issues.
There are plenty of things that we can do from our homes, workplaces, farms etc. to promote the feeding and roosting of local bat populations. A big issue is the decline of insect populations, due to the lack of native vegetation and increased use of pesticides. It is very important, not just for helping bat populations, but for all our favourite Irish wildlife that our insect populations retain high diversity and density.
A study carried out by Shiel et al. (1998) analysed the diet of Leisler’s bat in Ireland and also in English and German populations. Droppings were collected from six different pastoral sites in Ireland to decipher the main diet of bats, and the results showed a very varied diet. The main prey was found to be nocturnal swarming flying insects as expected. Other food sources for these bats included:
- Yellow dung flies
- Dung beetles
- Acari arachnids (mites and ticks)
- Aquatic larvae of insects (found in ponds, pools, streams etc)
- Lepidoptera, specifically moths
- Brown and green lacewings
- Ichneumonidae wasps
These findings indicate a dependence to human associated areas such as farmlands as dung flies, dung beetles and acari can all be associated with livestock. Lacewings are also commonly encouraged onto farmlands as their larvae prey upon nuisance mites and ticks. This shows how fragile a bat population could potentially be to their food source suddenly dying out because of insecticide use.
Attracting bats to your garden is best achieved by trying to replicate a natural environment. This can be done by growing plenty of broadleaf trees and shrubs, and not constantly cutting and pruning them. These encourage swarms of small flying insects along with other larger invertebrates to prey upon them to visit your garden, which in turn will promote a range of garden birds, small mammals and bats to visit depending on your location of course. The planting of evening nectar releasing plants such as evening primrose and greater stitchwort is also great for encouraging moths to feed, a favourite prey of bats.
Maintaining some wild areas in your garden is also important for promoting biodiversity. Hedgerows are of vital importance to a lot of invertebrate species, as are plants usually considered to be weeds. Nettles for example can really increase the insect diversity of a garden, which in turn increases the diversity of birds, amphibians and small mammals. Ponds are also fantastic for encouraging different wildlife into your garden, flying insects may lay eggs in the still water and their larvae would provide a new food source for bats to swoop for.
If you decide to go one step further, you could buy or build your own bat box for your local bats to roost in. These simple boxes can be made from a range of cheap materials from wood to sheet metal. They are also cheap to purchase online if craft isn’t your forte. These artificial roosts replicate the bats favoured nesting sites, which include hollows in trees, cracks and crevices in buildings or other man-made stonework, for example Daubenton’s bat favours roosting in the crevices of stone bridges.
These bat boxes can be attached to the sides of buildings, on the trunks of trees or can even be pre-installed into newly built houses or sheds. If you have a larger amount of land or a few different suitable features where bat boxes could be places, having a few different material boxes in different locations can give bats a greater selection of microclimates as they prefer different temperature roosts depending on whether they are rearing young or hibernating.
Bats are one the most unique and fascinating animals alive today, and for our country’s relative lack of diversity in terms of wildlife, we are blessed with several species of these soaring mammals. It is important that they are appreciated for the right reasons, such as their importance to ecosystems, their incredible body mechanics and the overall wonder and myth that comes along with them. In these times of welcoming distraction, going for an evening stroll or wrapping up and sitting in your garden may just give bats an open forum to spark imaginations and begin fascinations.
- Bat Conservation Ireland (for all of the information you’ll need on Irish bats!)
- Scientific American, 1998. How do bats echolocate and how are they adapted to this activity? https://www.scientificamerican.com/article/how-do-bats-echolocate-an/
- Shiel, C., Duvergé, P., Smiddy, P., & Fairley, J. (1998). Analysis of the diet of Leisler’s bat (Nyctalus leisleri) in Ireland with some comparative analyses from England and Germany. Journal of Zoology, 246(4), 417-425. https://www.cambridge.org/core/journals/journal-of-zoology/article/analysis-of-the-diet-of-leislers-bat-nyctalus-leisleri-in-ireland-with-some-comparative-analyses-from-england-and-germany/168560A4389463C2554A61A7C78BCC16
- Biodiversity: The best plants for attracting insects to gardens, 2019. BBC News, Science and Environment. https://www.bbc.com/news/science-environment-50663818
- Attracting Wildlife in the Garden, 2017. Fruit Hill Farm. https://www.fruithillfarm.com/info/2017/01/attracting-wildlife-in-the-garden/
All images sourced from Creative Commons.