Wildfire smoke reduces Little Eagle (Hieraaetus morphnoides) flight activity

ABSTRACT

There have been few empirical studies of the sensitivity of birds to the effect of air pollutants. In late 2019 and early 2020 the Australian Capital Territory (ACT) and much of south-eastern Australia were affected by extreme wildfire events and smoke extended to surrounding areas. Prior to this event, GPS transmitters had been fitted to a sample of Little Eagles Hieraaetus morphnoides in the ACT as part of a study of their movement behaviour. Three of these birds carried transmitters in the breeding season during the fires and in the previous breeding season. This offered opportunistic analysis of data from both periods to test for effects of smoke on the birds’ flight behaviour. The effects of particulate matter in the air of ≤2.5 microns in diameter (PM_2.5) and covariates on flight status were investigated with a binomial generalised linear model with logistic link. The birds were more likely to fly when there were low levels of PM_2.5 and the odds of flying decreased as density of PM_2.5 increased at a rate of 0.202% per ug/m³. None of the sample birds died during or after smoke exposure, although their respiratory system might have been affected.

KEYWORDS:

• Air pollution
• wildfire smoke
• particulate matter
• birds
• Little Eagle Hieraaetus morphnoides

Acknowledgments

We acknowledge the Ngunnawal People as the Traditional Custodians of the land on which this study is undertaken and pay our respects to Elders past, present and future. We are grateful to landowners and managers who allowed access to nest sites and hunting areas. This study was part of a wider study by the Little Eagle Research Group and we thank other members of the group for help with fieldwork and comments on this report; these being Jacqui Stol (CSIRO Land and Water, Black Mountain), Michael Mulvaney (Rtd. Conservation Research Unit, ACT Government), David Roberts (Ginninderry Joint Venture), Penny Olsen (Research School of Biology, Australian National University) and Don Fletcher.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed at https://doi.org/10.1080/01584197.2023.2267609