That doesn\u2019t mean we should abandon bat boxes \u2014 bats are already under threat due to disease and habitat loss \u2014 but as global temperatures keep rising, conservationists say the boxes need a few tweaks.\u00a0<\/p>\n
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A view looking straight up into one of the bat boxes on site at \u019b\u0313\u00e9x\u0259t\u0259m Regional Park in Coquitlam, B.C, which contains about 400 bats in just one of the very large boxes at the time. (Submitted by John Saremba)<\/p>\n
What exactly happened in 2018?<\/p>\n
It wasn\u2019t the first time the colony experienced dangerously high temperatures; the bats had survived a heatwave a month before the fatalities. So what was different this time? And if conditions had become unbearable, why didn\u2019t they simply fly away?<\/p>\n
Leah Rensel, a wildlife biology PhD candidate at the University of Montana, was studying the Port Coquitlam bats when the die-off occurred.\u00a0<\/p>\n
\u201cThe temperatures inside the bat boxes had exceeded, I believe it\u2019s 44 C, which is lethal for the species,\u201d Rensel said.<\/p>\n
Rensel suspects the bats\u2019 fiercely protective maternal instincts was the reason they stayed, noting the colony was likely going through parturition in July 2018, a time when the female bats gather to give birth.\u00a0<\/p>\n
\u201c[The babies] are really small \u2026 so the bats had these vulnerable pups and they didn\u2019t want to leave the roost, even though the conditions were too hot.\u201d<\/p>\n
Though expectant mothers seek out warm spots \u2014 so they can devote themselves to giving birth, nursing their young and hunting insects instead of temperature regulation, there\u2019s a limit to how much heat they can handle.<\/p>\n
\u201cI call it the Goldilocks zone,\u201d Rensel said, which falls between 35 C and 41 C for the little brown bat and the Yuma Myotis bat.\u00a0<\/p>\n
\u201cSo it’s not too hot and it\u2019s not too cold \u2026 so if you\u2019re a bat in a maternity colony and you find a roost that hits that most of the time, that\u2019s golden.\u201d<\/p>\n
But these little wooden boxes can heat up quickly, particularly when they\u2019re painted black and placed in direct sunlight, as the Port Coquitlam boxes were.<\/p>\n
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A cluster of bat boxes housing female Little Brown and Yuma Myotis bats in S\u0259h\u0259tl\u0259m Regional Park in Port Coquitlam. (Submitted by John Saremba)<\/p>\n
And the combination of higher temperatures and the stuffy conditions inside the boxes led to humidity, which is especially harmful to the inhabitants.\u00a0<\/p>\n
\u201cWhat climate change is doing is essentially increasing the temperature component of their microclimate,\u201d said Cori Lausen, director of bat conservation with the Wildlife Conservation Society Canada and Rensel\u2019s thesis adviser.\u00a0<\/p>\n
\u201cWhen you bring temperature and humidity together, that\u2019s heat stress,\u201d she said, noting that bats don\u2019t sweat, which makes it harder for them to cool down.<\/p>\n
Why bats are in danger<\/p>\n
Bats are under threat from more than just heat.<\/p>\n
Worldwide, habitat loss and forest fragmentation have reduced the availability of natural roosting sites and the insect-rich habitats bats rely on for food. In North America, the fungal disease known as white-nose syndrome has decimated their populations.<\/p>\n
Of the world\u2019s nearly 1,400 known bat species, 25 are considered critically endangered, 87 endangered and 110 vulnerable, according to the International Union for Conservation of Nature<\/a>.\u00a0<\/p>\n A world without, or with significantly fewer, bats could devastate ecosystems, because the animals perform natural pest control, suppressing insect populations that can ravage forests or farmers\u2019 fields, according to a 2019 paper<\/a> published in the Biodiversity and Conversation journal.<\/p>\n In tropical and subtropical forests, bats disperse seeds through their droppings, an important role in regeneration.\u00a0<\/p>\n
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