The North has been experiencing record summer temperatures for more than 40 years, with many places exceeding 40 degree Celcius. Combined with the impact of the "urban heat island" effect, the average heat at the same time in the big cities like Hanoi is harsher. The effect of hot weather on the life and activities of people, especially in urban areas, has been mentioned by many news agencies. However, the impact of these extreme weather phenomena on the living creatures in the urban environment receives less research.
Since 2009, scientists from the Institute of Ecology and Biological Resources have conducted research and monitoring of bat species in urban areas of Hanoi and its surrounding areas. Accordingly, bats are one of the wild animals remaining in Vietnam's urban areas. They play an important role in the urban environment, bringing many benefits to people, including helping destroy harmful insects such as mosquitoes or pests.
One of the most common bats in northern Vietnam is the Japanese pipistrellus abramus (Figure A). This species have been adapted to living conditions in urban areas, often nesting in slits, holes under the roof, under bridges, electric poles and feeding in open places such as rivers, lakes, street lamps. This species of bat usually gives birth to two or more pups, even four at a time. The reproductive season of this species of bat begins in spring-summer intersection and ends in July (Specifically, the female bats start their pregnancy in March and give birth in May while their young can be separated from mothers by mid-July). This is also the time when insects thrive, so they can provide food for the bats to nourish and care for the young.
Over the past few days, scientists from the Institute of Ecology and Biological Resources have recorded two cases of dead bats, and they all belong to pipistrellus abramus. The first case (Figure B) was a dead mother bat, with three baby bats born about one to two weeks previous, in Le Hong Phong Ward, Phu Ly City, Ha Nam Province, at 4p.m on June 3, 2017. The second case (Figure C) is an immature male bat individual, found in a densely populated area at Alley 109 on Truong Chinh Street, Phuong Liet Ward, Thanh Xuan District, Hanoi, at 1p.m on June 5, 2017).
Examination of dead bats in Hanoi as well as photos of buried samples taken in Ha Nam province showed that they had not been hurt by collisions with objects or traffic vehicles, or not been beaten by animals like dogs or cats. On the other hand, based on the findings over the past several years, we identified that the bats did not die due to a lack of food. Considering the time of bat deaths, at noon or afternoon when the temperature is recorded highest in a day, we reached the conclusion that they could die of heat. Accordingly, too high temperature made bats, especially those with weak resistance, such as young bats and mother bats which are raising many young bats at the same time, lose water quickly, and if water is not added promptly, their vital functions will fail.
Here are just two cases of bats that may have died due to hot sun, but the actual figures will certainly be greater because there are no comprehensive statistics. We can see some of the negative effects of extreme weather conditions caused by climate change, as well as urbanization.
Translated by Phuong Huyen
Link to Vietnamese version