Can Wind Farms Slow the Growth of Shorebird Populations?
Vulnerability of northern gannets to offshore wind farms; seasonal and sex-specific collision risk and demographic consequences (2020) Lane et al., Marine Environmental Research, https://doi.org/10.1016/j.marenvres.2020.105196
A green on green conflict is what occurs when forms of renewable energy can have a potentially negative effect on the local environment. We see it in hydropower disrupting freshwater fish populations, or in the case of today’s paper, wind farms causing bird deaths. Marine shorebirds are often killed by wind turbines, yet it’s not totally clear to what extent population numbers are impacted by these deaths.
Additionally, whether wind farms are more dangerous to male or female, old or young birds could have a big impact on whether these bird deaths affect population numbers in the future. Today’s authors wanted to investigate this question, using a population of northern gannets off the coast of Scotland.
What They Did
The researchers successfully equipped just under 200 birds with GPS loggers and pressure loggers, which were not only capable of tracking each bird’s position, but their height when flying as well. They were then able to estimate how high birds of each sex were flying when close to wind farms, and therefore calculate the risk of a collision.
They recorded trips taken by the gannets both before chicks had hatched and while chicks were being reared. The combined data enabled the researchers to then calculate the predicted number of gannets killed of each sex, and integrate that number into a population model showing the effect of wind farm deaths on the population long-term.
Did You Know: Wind Energy As a Threat To Birds
Wind farms get a lot of negative press, much of it concerning their role in increased bird deaths. Yet as this paper from last decade shows, wind farms are a drop in the ocean compared to other threats like land use change and fragmentation, invasive species, outdoor cats, and in the case of seabirds, getting swept up as by-catch by fishers. Among those threats is also, you guessed it, climate change.
What They Found
Gannets seemed to make much longer trips before hatching than while raising chicks, and females almost always made longer trips than males. Both sexes spent a lot of flight time near wind farm sites pre- and post-hatching.
The population model estimated that about 1500 northern gannets would die every year from wind turbines, with around three-quarters being female. While that sounds like a lot, it didn’t cause the population growth of the gannets to decline. It’s also important to note that the figure doesn’t account for density-dependent effects: the deaths of those 1497 gannets may open up resources and cause more successful breeding among the surviving gannets, further lessening the effects of the wind farms.
There is a lot of uncertainty present in these predictions, and giving a number like 1474 bird deaths without presenting more details on best and worst-case scenarios would normally seem a bit dodgy. Given that the paper goes onto show that the number is still well below what would be needed to cause a population decline, it gets a pass.
In this example at least, wind farms don’t seem to have a profoundly negative effect on gannet populations. This is of course just one scenario, and it was conducted using the world’s largest northern gannet population. The situation could be worse for a smaller colony.
But my main takeaway from this paper is that it sets a great framework for other research projects to follow. It’s a model that can be easily applied to other locations, and can help successful planning of future wind farms.
Dr. Sam Perrin is a freshwater ecologist who completed his PhD at the Norwegian University of Science and Technology and is wondering how much electricity constantly blowing hot air can produce, and whether he can start a miniature wind farm in his office with said hot air. You can read more about his research and the rest of the Ecology for the Masses writers here, see more of his work at Ecology for the Masses here, or follow him on Twitter here.