Stowaway bats
In October of 2023, a cargo ship arrived in Nova Scotia, originating from Germany and stopping in the United Kingdom along the way. On board this ship was a tiny stowaway that went unnoticed until the ship moored at its Eastern Canadian destination. Upon arrival, a cargo inspection was conducted when the small stowaway was discovered, clinging to the back of a car. The stowaway was quickly recognized as a bat. The Nova Scotia Department of Natural Resources was contacted, who in turn contacted the Canadian Wildlife Health Cooperative (CWHC), Atlantic Region. Considering the journey of the ship this bat was found on, we had a suspicion that this may not be a species native to Canada. The bat was submitted to our Atlantic Region centre for health surveillance and our suspicion was quickly confirmed. While we didn’t immediately know what species the bat was, we instantly knew it wasn’t any of our native species, based on the external body features we use to identify our bat species. Our bat team used a key for European bat species identification and used the pattern of blood vessels in the wing (a feature we do not use for species identifications in Atlantic Canada) to confirm the species’ identity as a Nathusius’ pipistrelle (Pipistrellus nathusii). The Nathusius’ pipistrelle is a fairly widespread species throughout Europe and is known to migrate and fly distances over the seas in that region as well. Where exactly the bat jumped aboard the ship is not known, but it is definitely a species that would not typically occur on our continent.
Examining wing veins of a stowaway bat to help with species identification
The tail tip extending past the tail membrane was a notable feature of this unidentified bat specimen
Then, in January of 2024, CWHC Atlantic Region received a report of a bat that died on Sable Island, about 175 kilometers off the coast of mainland Nova Scotia. This bat was also submitted to CWHC Atlantic Region for health surveillance and post-mortem examination to determine cause of death. At first glance, it looked like one of our common Myotis species, but its external appearance was not typical of our local bat species. The tip of its tail extended past the tail membrane, a feature that does not match any of the species found in Atlantic Canada. It turns out we had another bat on our hands that is not typically found in this geographical region. While its external features did not match our native species, they also didn’t perfectly match any other species from Europe or the rest of North America that we were able to determine, and to this date the identity of this bat remains a mystery to us. To accurately identify it, the CWHC Atlantic will need to send some tissue from the bat to a lab specializing in genetic identification of bats. Different from the Nathusius’ pipistrelle, this specimen was not confirmed to have arrived at its final destination by any vessel or other mode of human transportation. While it could have come from a vessel sailing near Sable Island, it may also have flown there on its own, which is especially likely if it turns out to be a species found in the Eastern United States after all.
There are multiple ways in which a wild animal could end up outside of its normal range. Weather events, especially those with high winds, are known to blow birds and bats off course, with birds being reported in continents across oceans, and North American bats ending up in Iceland. Warming temperatures, due to climate change, can also cause an animal to wander outside of its normal range, with animals moving further north than usual as the increasing temperature can render previously unsuitable areas more useable for the species. Such is the case with common vampire bats moving north towards the United States. And of course, animals can end up hitch-hiking their way across continents or oceans on board vessels, planes, trains, long-haul trucks, and recreational vehicles, as did our stowaway Nathusius’ pipistrelle.
Accidental translocation of species, including bats, outside of their natural ranges is occasionally officially documented, but likely not nearly as often as it actually happens. Either an animal is not recognized by the finder as a potentially introduced species and may subsequently be set free, or the animal gets out into the wild before anyone even notices. This is especially likely with small and fast animals that tend to move under the cover of darkness such as bats.
A North American Myotis bat species with visible signs of white-nose syndrome
Invasive species are organisms introduced to and that often thrive in a new area, causing harm to the economy or native plants and animals of the region. As a result, they can be devastating to ecosystems and the species living within them. Bats as tiny flying mammals are likely candidates for accidental introduction involving long-distance movements. However, there are no published records of any bat species, other than the common vampire bat, becoming an invasive species. This is possibly due to the life history traits of bats, specifically a low reproductive rate and restricted habitat and climatic requirements. An additional concern is not the introduced animal itself, but instead about what micro-organisms the introduced animal might be carrying that could be problematic for our ecosystem. We know that the fungus which causes white-nose syndrome originally came from Europe or Asia and was accidentally introduced to North America. While it is considered most likely that this fungus was accidentally introduced by people, we worry that further introductions of additional strains of this fungus (or other micro-organisms and viruses), be it by people or by stowaway animals, could cause additional problems for our native species and the ecosystems in which they live.
Increasing public awareness about the risks of invasive species and teaching people how to minimize such events from occurring is an important way to mitigate their potential risks. Long-haul transportation authorities should conduct close inspections of cargo for stowaway wildlife before departure from and upon arrival to a destination. The public can also help by conducting such inspections of their recreational vehicles prior to travelling to a new location because bats, in particular, like to roost under awnings and inside folded umbrellas. In instances where an animal is found in such a spot after travelling a long distance (inter-provincial and international travel), the local Department of Natural Resources or regional wildlife agency should be contacted for advice.
Looking after wildlife is everyone’s responsibility. Report sick and dead wildlife to the CWHC, and report wildlife species that may be out of place to those responsible for wildlife in your local area. Your attention to such circumstances can make a significant difference in keeping Canada’s wildlife and ecosystems healthy.
Article submitted by: Jordi Segers, National Bat Health Program Coordinator, CWHC National Office
