20 June, 2024

We’ve just experienced a major heat wave, surprisingly early in the year, breaking several records in the province. This heat wave is also occurring at the height of birds’ breeding season, when many young birds are still in the nest. Should we therefore expect an increase in mortality?

A bit of avian biology

It may be easy to be alarmed for birds in these conditions, if we compare the way we manage these high temperatures. One important fact, however, is that the body temperature of birds, especially passerines, is higher than our own, varying between 39 and 43 degrees Celsius. This variation is found both between species and between the sexes.

To cope with high temperatures, and despite the absence of sweat glands (which enable us to perspire and lower our body temperature), birds will pant to dissipate heat and hydrate and bath as much as possible (importance of wetlands), giving priority to the cooler hours of the day.

Finally, temperature has a major impact on the development of organisms, both chicks and the insects they feed on. In this respect, the literature shows both positive and negative impacts, depending on the species studied (Sauve et al. 2021).

Different impacts

A large number of scientific studies have examined the variability of bird reactions to high temperatures. As is often the case, there are no uniform conclusions among birds, and that’s just as well!

In addition to the variability observed between species, geographical zone can have an additional impact. Indeed, these heat episodes in desert areas can be catastrophic, with cases of mass mortality (Fey et al. 2014). In temperate environments, a study (Pipoly et al. 2022) showed that birds breeding in forest environments could suffer more from heat episodes than individuals living in urban environments. They had lower body mass and tarsal length, and suffered increased mortality when they experienced a greater number of hot days during the nesting period.

These morphometric measurements, nesting success and daily ambient temperature are all currently being recorded as part of our work at Cap Tourmente NWA, and will help us learn more about the effects of heat.

This project was carried out with the financial support of Environment and Climate Change Canada.

What can we expect in the future?

The difficulty that organisms will face in the future lies more in the variability of climate change, than in temperature increase alone. But more studies are needed to better understand and anticipate the consequences these global changes will have on avian fauna.

While we can expect an increase in avian biodiversity in the province over the next few years, with what is known as the northern biodiversity paradox (Berteaux et al. 2021), the ability of these organisms to cope with significant temperature increases may also be variable.

We can therefore expect species more accustomed to living in warm environments to survive better than northern species. Unfortunately, climate change will also have an impact on forest fires and droughts, which are unlikely to spare forest birds.

Given the variability of the effects of climate change on bird species (Andreasson et al. 2020), almost as variable as the diversity of bird species, it is difficult to predict with any certainty which species are likely to benefit from heatwaves, and other climatic effects and which are likely to suffer. This is the role and importance of the long-term monitoring we’ve been carrying out at the Tadoussac Bird Observatory since 1993. As much as migration monitoring projects give us a better idea of reproductive success, so that we can link it to environmental factors, so do projects carried out during the birds’ breeding season.


Andreasson, F., Nilsson, J. Å., & Nord, A. (2020). Avian reproduction in a warming world. Frontiers in Ecology and Evolution, 8, 576331.

Berteaux, D., Blois, S. D., Angers, J. F., Bonin, J., Casajus, N., Darveau, M., … & Vescovi, L. (2010). The CC-Bio Project: studying the effects of climate change on Quebec biodiversity. Diversity, 2(11), 1181-1204.

Pipoly, I., Preiszner, B., Sándor, K., Sinkovics, C., Seress, G., Vincze, E., … & Liker, A. (2022). Extreme hot weather has stronger impacts on avian reproduction in forests than in cities. Frontiers in Ecology and Evolution, 10.

Sauve, D., Friesen, V. L., & Charmantier, A. (2021). The effects of weather on avian growth and implications for adaptation to climate change. Frontiers in Ecology and Evolution, 9, 5.