BUILDING RESILIENCE FOR BATS

This short 14 second video shows the output from a Echo Meter Touch 2 bat detector that plugs into a mobile phone or tablet and translates a bat’s ultrasonic sounds to something humans can hear.

The big brown bat sounds in the recording show the bat emitting ‘chirps’ while searching for insects (where bars are more spaced out) as well as a feeding buzz when it detected and emitted faster sounds to lock onto the insect before capturing it (where bars become closely spaced). This clip was recorded right here in Waterton Biosphere Region in May of 2020.

The clip on the left is of Little Brown Bat calls recorded using a home-made detector (heterodyne downconverter) coupled with a Tascam Porta II cassette tape unit. The background noise is mostly insects that issue sounds near 23 KHz. The chirps and pops are bats echo-locating.

The ‘fart’ sounds are them catching prey. The rapid chirps are them landing (roosting) in the trees.

Bats make up roughly 20% of all mammalian species around the world and contribute vital ecological and economic values to many ecosystems through pollination, seed dispersal, and pest control. They are an important part of the ecosystem in Waterton Biosphere Region.

Bats are the primary consumers of night-time insects, including mosquitoes and agricultural or forest pests: a single individual can consume 100 times its own weight in insects each year. Their continued presence in WBR is important for both the environment and the economy.

Migratory bat species typically arrive in Alberta during April and May for their reproductive season. The southward migration begins after pups are weaned with bats leaving the province in August through to early October. Overwintering locations for these migratory bats are thought to include areas in the southern United States and Mexico, California, the Pacific Northwest, and possibly warmer locales in  British Columbia.

Long distance migrants include:

• Hoary Bat
• Silver Haired Bat
• Eastern Red Bat

‘Resident’ species may undergo seasonal movements of up to several hundred kilometres but likely remain in or close to the province. Overwintering locations (hibernacula) for most resident bats in Alberta also remain largely a mystery. Suspected habitats include abandoned caves, mine shafts, deep rock crevices, and buildings but the few identified hibernaculum areas account for only a small proportion of our bat population. Local migrants include:

• Big Brown Bat
• Little Brown Bat
• Northern Myotis
• Long-eared Myotis
• Long-legged Myotis
• Western Small-footed Myotis

The Western Small-footed Myotis is the only resident species not confirmed in WBR.

DIET

Alberta bats are all insectivorous, pursuing prey items by hawking (catching flying insects while in flight) or by gleaning (gathering insects off foliage or the ground), and the importance of their insect consumption cannot be understated. Lactating little brown bats can consume their own body weight each night in prey.

Annual consumption rates of big brown bats can total in the millions of insects a year at a colony level. Though no similar analysis has been conducted in Canada, pest control services provided by bats represent an average $23 billion value to the U.S. agricultural sector each year.

For more information on insect preferences of Alberta bats and influence of body size, flight speed, and habitat on bat diet, refer to our Bat Conservation Plan.

FORAGING HABITAT

Particular habitat preferences can vary among bat species and breeding status, with some preferring treed areas, others open waterbodies, and yet others selecting the interface between two habitats. Lactating little brown bat females typically choose to forage in close proximity to their maternity roost using airspace over open water or near shorelines and along edge habitat.

Riparian and wetland areas (along the Old Man, Castle, Waterton, Belly, and St Mary’s river valleys and associated smaller creeks and tributaries) provide natural foraging areas for bats, as these areas typically host concentrations of insect prey.

The importance of riparian areas, springs, open river valleys, and treed stands for foraging bats in a grassland landscape and proximity to adequate roosting habitat may increase attractiveness for some species. Treed habitat may also provide connectivity through the landscape for bats that are commuting between roosting and foraging sites but that are reluctant to cross open areas.

WATER SOURCE FOR DRINKING

Most species of bats drink by skimming the surface of a waterbody with their bottom jaw while in flight. Accordingly, they need open water sources free from flight obstacles, in other words a clear ‘swoop zone’.

Waterbodies such as ponds, lakes, dugouts, and slow-moving streams can serve as open, unobstructed drinking water sources for bats. The required size of the waterbody will depend on the size of the bat species and their maneuverability, but can range from 3 m for smaller species with short, broad wings to 30 m for larger-bodied, less maneuverable species.

Bat habitat can be found in both natural areas and human-made structures. Large diameter cottonwood and poplar, especially dead or decaying trees, provide natural roosting areas. Farms and ranches with used or abandoned buildings may also provide significant roosting habitat for some species.

Preferred roost type depends on the species and, in some cases, on the sex and reproductive status of the individual.

Reproducing female little brown bats, the target of the Waterton Biosphere Region Building Resiliency for Bats project, select warm and safe locations to raise their pups in colonies, while males and non-reproducing females choose slightly cooler locations and typically roost alone or in small groups. The warm environment in maternity colonies helps minimize energy required to keep pups warm and maximize rapid pup growth.

WHITE-NOSE SYNDROME (WNS)

Bats in North America are threatened by white-nose syndrome (WNS), a fungal disease that has killed over 7 million bats since first detected in 2006 in New York. In 2022, the fungus was confirmed in eastern Alberta and is expected in WBR within the next year or two. We are now collecting and testing spring guano from accessible roosts to detect its arrival. WNS affects hibernating bats and at some sites, 90 to 100 percent of bats have died. Several species are affected.

Three of the hardest hit, little brown myotis (Myotis lucifugus), northern myotis (Myotis septentrionalis) and tri-colored bat (Perimyotis subflavus) are listed as Endangered under Canada’s Species at Risk Act. Click here to find out more about WNS.

The syndrome is caused by white fungal growth on infected bats’ muzzles and wings. The cold-loving fungus infects bats during hibernation, causing them to arouse more frequently from hibernation and burn up valuable fat reserves they need to survive the winter. The disease spreads by bat-to-bat contact in colonies or bat contact with contaminated surfaces.

In the face of population-level challenges for these important insect predators, WBR works with local landowners to build resiliency for bats, in particular little brown myotis (or little brown bat). A resilient bat population will be quicker to recover from disturbances like WNS or severe weather through adapting to stresses, better resisting disease, and/or sustaining fewer mortalities.

White-nose syndrome occurrence map (March 5, 2023). White-nose syndrome has been moving westward over the last 15 years. Data available at: https://www.whitenosesyndrome.org.

WIND ENERGY

Wind energy primarily affects migrating species of bats in WBR including the hoary bat, silver-haired bat, and eastern red bat (rare but sometimes present). Fatalities are greatest during the late summer and fall migration period. Specific reasons as to why impacts are not noted in the spring migration as well are unclear but perhaps the bats take a different flight route or elevation. Fatalities occur when bats collide with the spinning turbine blades or suffer injuries due to rapid changes in air pressure near the blades (barotrauma). Wind turbines kill hundreds of thousands of bats annually in North America with Canadian fatalities projected to reach 166,000 bats/year by 2035 due to increased installations and capacity.

Tree-roosting migratory species, such as hoary bat, silver-haired bat, and eastern red bat, account for 73% of fatalities across Canada while little brown bat and big brown bat account for another 21%. Though cumulative numbers have not been published for the WBR area, bat activity and fatalities are typically higher at turbines in southwestern Alberta than at locations further east in the province.

DEGRADATION/LOSS OF FORAGING HABITAT

Riparian habitats are important foraging sites for bats, particularly females, and bat use of such habitats may be affected by disturbances that alter the tree or shrub cover. Bats also use treed riparian habitats for commuting lanes or roost sites. Although riparian areas can offer forage, water, and shelter for livestock, associated trampling of seedlings or shrubs, loss of dead or decaying trees, and a decrease in the number of plant species can degrade these important habitat areas for bats. Activities that degrade or drain wetlands can also impact habitat quality and associated insect prey for bats. Wetlands with emergent vegetation are used less by bats than open wetlands as bats may have difficulty echolocating or finding a clear swoop zone when drinking due to the vegetation. However, such vegetation does support insect prey.

DISTURBANCE OR LOSS OF ROOST SITES

Disturbance of roost sites, either natural or building roosts, can impact bats relying on the sites by causing them to lose pups, breaking up large colonies, causing them to travel further to roosts or foraging habitat, and decreasing their likelihood of returning to a trusted/secure site in subsequent years.

Loss of building roosts typically occurs when a landowner or resident decides to actively exclude bats (e.g., patch holes or seal entry points with spray foam), to remove structures used for roosting (e.g., demolish old barn), or when structures deteriorate and succumb to weather or age (e.g., wooden granary roof collapses). The impact to bats will depend on the method and timing of roost elimination, availability of other suitable habitat, bat species, as well as sex and reproductive status of the bats using the roost. For example, females show strong loyalty to their maternity roost, so the summer removal of the roost will disrupt both current and future generations. The impact of natural roost site loss may depend on the availability of alternate sites in the nearby area: maintaining seedling, sapling, mature, and decaying trees is necessary to ensure constant supply of potential roost trees in the future.

Please see the Stewardship Opportunities section of this page for more information on reporting roost sites and other ways you can help bats in WBR.

For more information on additional threats to bats in WBR than what you see here, please refer to our Bat Conservation Plan.

WHAT THE WBRA IS DOING TO HELP

Waterton Biosphere Reserve Association (WBRA) began the Building Resilience for Bats project in 2019 to work with local landowners to build resiliency for bats, in particular little brown myotis (or little brown bat). A resilient bat population will be quicker to recover from disturbances like white-nose syndrome (WNS) or severe weather through adapting to stresses, better resisting disease, and/or sustaining fewer mortalities.

By confirming buildings that support bat roosting (e.g., barns, sheds, granaries, houses), WBRA helps landowners decide how best to protect such sites or provide alternate roosting areas if the original structures are damaged or scheduled for removal.

Landowners who steward high-quality roosting and foraging habitats will support successful rearing of pups and help maximize the health of adults heading into hibernation. Periodic monitoring of roosts can help detect population changes as well as identify target sites for mitigation measures currently being tested to lessen the impacts of WNS (e.g., inoculation with probiotics/anti-fungal agents, oral vaccines).

WBRA staff help landowners identify and monitor maternity roosts for bats, specifically by identifying entry and exit points, conducting roost counts, helping determine the particular bat species through bat detectors and guano collection, and discussing ways to maintain or improve habitat for bats on a given property.

To correspond with when mother bats have flightless pups in the colony, our roost count window runs from early June to mid July, while site visits to discuss bat roosts and bat habitat continue through the summer. You can read about the results of our previous Field Seasons in the WBRA Outreach & Fieldwork section of this page.

Bat Conservation Plan for the Waterton Biosphere Region

Our ongoing bat work is guided by a Bat Conservation Plan for the Waterton Biosphere Region that synthesizes the early knowledge and experience gained during this project. The plan details conservation objectives and strategies, outlines stewardship activities that could be pursued, identifies required resources, and suggests potential partnerships going forward. The target areas are outreach and education, identification and monitoring of roosts/colonies, and habitat protection and enhancement.

WHAT YOU CAN DO TO HELP BAT HABITAT

You can help bats in your area by becoming a steward of good bat habitat. Landowners can help promote resilient bat populations by maintaining important roosts that help females successfully raise pups and by ensuring adequate prey and foraging locations to maximize the health of bats heading into hibernation.

Maintaining good bat habitat goes beyond ensuring roost sites in buildings are protected wherever possible. Many bat species, including the little brown myotis, will use natural roosts such as spaces under loose bark; cavities and crevices of standing dead trees or older live trees; cracks and crevices of cliffs, rock bands, and boulders; or erosion cavities of rock or solidified mud.

But in addition to adequate roosting sites, bats rely on accessible drinking water and sufficient insects for food. Bats drink by dipping their bottom jaw in water while flying, thus ideal drinking sites will be open, calm waterbodies that are free from thick vegetation or other flight obstacles and that are close to their summer roosts (e.g., less than two kilometers away for female little brown bats). These waterbodies, as well as streams or rivers, often support the insect populations important to foraging bats. Landowners who implement best practices to maintain healthy riparian areas, avoid drainage of wetlands or seasonal wet areas, and preserve known/potential natural and man-made roost sites will be protecting habitat for little brown bats as well as several other at-risk insectivorous species.

Beneficial Management Practices 

Beneficial management practices for bats maintain roosting sites or potential roosting habitat, including the recruitment of young cottonwood and poplar trees that will produce future mature and old-growth age classes conducive to roosting. This could include practices that avoid grazing riparian areas during the spring when soils and stream banks are more susceptible to damage and in the fall when woody vegetation is most vulnerable to browsing or placing salt and minerals away from waterbodies to draw cattle away from riparian areas. Similarly, practices that promote diverse vegetation composition and structure across the landscape (e.g., avoid intensive grazing; use rotational grazing with light to moderate stocking rates), particularly in treed stands and riparian areas, will positively impact insect diversity and abundance and thus promote high quality foraging habitat for bats. Ensuring water troughs, tanks, rain barrels, and other small containment devices for drinking water are covered or have escape options suitable for bats is one example of a beneficial management practice to promote safe, healthy drinking water sources for bats.

Considerations in Using Bat Boxes

Bat boxes or bat houses are often viewed as an easy conservation or habitat enhancement tool to help local bats, and indeed they are sometimes used by little brown or big brown bats or occasionally long-legged myotis. But bat houses also frequently sit unused by bats or have been the location of mass mortality events due to overheating. Research is ongoing to determine whether bat boxes are beneficial or detrimental to local bats in light of climate change and to identify what features of bat boxes provide the greatest likelihood of supporting healthy bat populations.

Maintaining natural roost habitat is a proven method of supporting local bat populations. Natural roosts offer characteristics appealing to a broader range of species (by including those species that will not use boxes). In addition, natural roosts provide options for bats to move sites based on their current needs (e.g., different sun orientation/cooler temperatures during hot spells, lower parasite levels in roost).

Accordingly, consider these factors if you choose to install bat boxes on your property:

• Multiple boxes at multiple orientations will provide more microclimate options for bats, akin to a forest with a cluster of roost options.
• Multi-chamber designs with passages between chambers will better allow females with dependent pups to move within the box based on thermal needs.
• Regular maintenance should factor into your installation. The box(es) should be checked annually to clean out any unwanted visitors (e.g., wasp nests) and ensure weathertightness.
• Monitoring of your bat box(es) can help provide valuable data to current research, even if the box is not used by bats! Information on your bat box can be submitted to the Canada-wide bat box project.

See What You Can Do To Help Monitor Bats below on how to monitor bat numbers in active bat boxes and submit roost count data.

If you want to learn more about ensuring your property has high-quality natural habitat to support local bats, check out Alberta Community Bat Program’s Building Bat Friendly Communities Program Guide by clicking here. If you want to learn more about bat boxes, designs, and installation, check out Alberta Community Bat Program’s Building Homes for Bats guidelines by clicking here.

WHAT YOU CAN DO TO HELP MONITOR BATS

A great way to make sure bats are getting the help they need is to report a suspected roost to the Waterton Biosphere Reserve Association by emailing eanderson@watertonbiosphere.com. 

Landowners who suspect building-roosting bats on their land can contact us to discuss how to confirm the roost and how to monitor the colony size. We can help you better understand the habitat features supporting local bats and understand how to best manage that habitat.

Reporting maternity roost locations to Waterton Biosphere Region (or the Alberta Community Bat Program) also helps identify target locations for novel techniques to combat WNS (e.g., inoculation of bats with probiotic bacteria cultures to decrease mortality or application of vaccines) as they are tested and become more widely available.

Once a suspected roost is found and reported, landowners can monitor the roosts and conduct roost emergence counts when bats return in the spring. Ideally, two roost emergence counts should be conducted before pups are able to fly, and two counts afterwards to see if your bat numbers are changing. But any level of counting can help provide valuable data. WBR can provide guidance on how to conduct a roost count as well as how to collect and submit guano to identify the species. For this information you can contact us at eanderson@watertonbiosphere.com. When handling guano, be sure to wear gloves and a mask. Wild bats in either natural or man-made roosts have very little chance of transmitting diseases to humans, unless handled without proper protection.

Bats at overwintering sites are sensitive to disturbance as premature awakening can use valuable energy and lower their chance of surviving the winter. Avoid disturbing known overwintering sites if at all possible, but report any potentially new or previously unknown sites as there is a shortage of information on overwintering bats in WBR and elsewhere.

Waterton Biosphere Reserve Association’s Building Resilience for Bats project was created in 2019 in a collaborative effort to help bats provincially. Our outreach and data are helping raise awareness of bat conservation and are contributing important information on known roost sites in southwestern Alberta.

Waterton Biosphere Region’s (WBR) conservation staff have helped landowners to identify and monitor maternity roosts for bats. To correspond with when mother bats have flightless pups in the colony, our primary survey window for roost counts runs from early June to mid July. Maternity roost counts follow the Alberta Community Bat Program protocol where participants (i.e., biologist, landowner, other volunteers) count bats leaving the suspected roost exit for one hour after sunset. When guano (bat poop) is accessible, we collect a sample for lab analysis of the bat species using the roost. We are sometimes able to get a sense of bat species in the area using bat detectors like the one shown to the right.

Occasional visits are also held with landowners at properties known to support bats but where specific roost locations are unclear or when we want to sample guano from a new roost location after the count window had closed. These visits provide an opportunity to explore bat habitat in the area, discuss ways to maintain or improve habitat for bats on a given property, and sometimes employ the bat detectors to identify possible species using the area.

FIELD SEASON RESULTS

A total of 28 bat roosts have been reported to date through our Building Resilience for Bats project, and at least 5 of these roosts are sufficiently large enough to qualify as high priority roosts that are important to monitor annually (i.e., detected species is little brown bat, colony size is over 100 individuals, and no exclusion is planned). Consistent monitoring at such roosts can help us detect changes in the population that may happen when white-nose syndrome spreads throughout Alberta.

Little brown bats appear to be the most common species detected in our guano sampling, consistent with findings province-wide in Alberta where 86% of building roosts are used by little brown bats. Big brown bats were identified at three locations, each with multiple roost sites on the property. Bat detectors have also indicated the presence of long-legged bats and the occasional hoary or silver-haired bat at various sites in WBR.

A summary of our field season results is shown in the table below:

Our highest roost count saw 319 bats exiting the roost for their nighttime feast one early August evening in 2024.  

Pups of little brown bats (the focus of the Building Resilience for Bats project) are typically born in late June/early July and take their first flight at 3 weeks of age. By 4 weeks of age, they are weaned, self-sufficient members of the colony and begin foraging and fattening in preparation for hibernation.

Additional guano sampling occurs at select roosts in conjunction with our partners at Alberta Community Bat Program (ACBP). They are monitoring early-season guano for the fungus that causes white-nosed syndrome to detect its spread into and through Alberta. ACBP is also conducting research into the specific insects contributing to the diet of bats in agricultural areas.

The following map shows the locations of the site visits completed to date. Some locations have more than one roost at the site. An individual map of the 2020 site visits can be viewed here, the 2021 map here, the 2022 map here, and the 2023 map here. A big thank you to the ACBP, roost count volunteers, and the landowners who gave access to their properties and roosts – together we are all working to maintain bat populations in WBR!

Acoustic Monitoring

Acoustic monitoring of bat activity can lead to early detection of population changes as well as identification of potential target sites for mitigation measures currently being tested to lessen the impacts of white-nose syndrome (e.g., inoculation with probiotics/anti-fungal agents, oral vaccines).

This acoustic monitoring is accomplished through the deployment of a specialized Acoustic Recording Unit (ARU) for a minimum of 4 nights in an area agreed upon by the landowner and WBRA staff member. The ARU is programmed to start recording at dusk and stop recording at dawn to reflect the typical bat activity window. These recording results are then run through a software program designed to recognize ultrasonic frequencies emitted by bats as they navigate and feed using echolocation.

The audio recording results are presented to us as a visual representation of these recordings. It is important to note that some bat species calls can closely resemble the calls of other species and the software technology has not been 100% reliable in differentiating such species. To offer a more accurate representation, we group these overlapping bat species together.  

This type of prolonged nocturnal acoustic data collection would not be feasible for our staff to accomplish without the ARU. 

Our acoustic monitoring efforts aim to contribute to the NABat Alberta Monitoring Hub, which is a centralized bat data hub for the province of Alberta.  Provincial data is then shared to the broader North American Bat Monitoring Program (NABat).
 

 Habitat Stewardship Projects

White-nose syndrome is predicted to spread within WBR and bat populations are expected to decline. There is some evidence from eastern North America suggesting that some populations may be developing a resistance to the disease. Supporting bat populations during this time, through habitat stewardship of roosting, drinking, and foraging sites, may help the recovery of future populations.

One way Waterton Biosphere Reserve Association is building bat resilience is through habitat stewardship projects such as installing bat houses or duplexes to provide roosting habitat where it is expected to be lost. When natural bat roosting habitat is absent, bat houses can be helpful to support bats on the property.

Bat houses are most effective when:

• Bats are currently roosting on the property in buildings or mature trees and these roosting locations are expected to be lost or demolished. Bat houses may compensate for the loss of habitat
• There are bats roosting in a structure the owners would like to exclude them from
• The bat house will be available to bats for many years as bats typically return to the same roosting area.

For more information on beneficial management practices for bats in WBR, please see the Stewardship section.

Community Events

Waterton Biosphere Reserve Association hosted a Starry Nights & Silent Flights event, supported by staff from the Alberta Community Bat Program and Dark Sky Guides.

We have compiled a few resources with more in-depth information for you . Click on the images to access the full pdf documents.