Published on August 14th, 2018 | by Jake Richardson0
Rising Temperatures Could Cause Common Songbird Population To Collapse
August 14th, 2018 by Jake Richardson
University of Missouri researchers have found that a common songbird, the Acadian flycatcher, could decline greatly in numbers within this century if the climate continues to increase in temperature. In fact, it is possible it could be driven into near extinction in just 90 years. Dr. Thomas Bonnot and research wildlife biologist Frank Thompson collaborated on the research, and Bonnot answered come questions for CleanTechnica.
The mechanism we suspect is that warmer temperatures alter the behavior of nest predators such as snakes and other birds. In the case of snakes, which are ectothermic, higher temperatures increase activity levels and metabolic requirements and thus they may be looking for more prey. And we actually have additional data to support this idea that predation increases with temperature.
If climate change continues on its current path, how much of a die-off will this songbird species experience?
The most severe climate scenario we considered assumes the Representative Concentration Pathway (RCP) 8.5, which is not only the highest but can also be considered the business as usual scenario that would take us down the current path. Under that scenario we project a 34% risk that flycatchers in the region would decline by 99% or more. Now, these estimates assume that many other factors such as habitat do not change with climate. But, we know that will not be the case so it is certainly possible that the risk could be higher or lower given other changes.
If its population is reduced to near extinction, what impact will that within its ecological niche, or web? Which other species will be impacted by its absence?
Just look at the processes reflected in this study; that rising temperatures influence nest predators, which affects productivity, and ultimately threatens millions of birds. I think that illustrates the critical balance of interactions between all species in any ecosystem. And so while I can’t say what the exact consequences of losing flycatcher or similar birds would be, these results alone suggest that substantial impacts can happen from even intricate changes. Aldo Leopold said “If the land as a whole is good then every part is good, whether we understand it or not.”
Will it be driven into extinction if climate change increases unchecked?
The short answer is I don’t know. It is important to remember that our predictions pertain only to the flycatchers in a defined region in the Midwest, when in fact this species is distributed across the eastern US. We can’t say what the impacts of climate change would be in these other regions because the nesting and predator processes vary across their range. And we know there will be the potential to adapt. We are already seeing species of birds that are shifting ranges northward and arriving to breed earlier. In both of these cases that could alleviate this effect somewhat. Additionally, we are unsure how climate change might affect the predator species too which would alter the underlying impact. We can be confident that things will change, we just can’t be sure how.
How would reducing forest fragmentation help the Acadian flycatcher survive?
Another separate process that affects breeding productivity of forest songbirds in the US is nest parasitism by brown-headed cowbirds. Scientists have known about this for decades and it continues to be a threat. Cowbirds will lay their eggs in songbird host nests, leaving the songbird parents to raises it with their offspring. But, cowbird chicks often out compete the host’s chicks for food causing loss of fledglings. Or the hosts may even abandon the nest resulting in total loss. Cowbirds are highly associated with habitat fragmentation because they inhabit the developed and agricultural lands that cause the fragmentation. And then they fly into the nearby forest to find host nests. So reducing the amount of forest land that is fragmented by other land uses can keep cowbird population away from songbirds, promoting better reproduction.
Could the species simply move further north to find cooler temperatures in order to increase its chance of surviving climate change?
Potentially, and we are seeing evidence that many birds are doing this. I think this would not be a conscious decision by the birds but, rather a passive process whereby populations of birds in northern, cooler areas do better overtime while populations in the original areas start to do relatively worse.
Are other birds like the Acadian flycatcher as vulnerable as it is to climate change?
Yes! Many songbirds in this region are affected to varying degrees by the same processes. So this should prompt concern for those other species that are less common or already at risk.
Outside of scientists, is anyone paying attention to the Acadian flycatcher, how could it get more attention?
That is a good question. Environmental groups have always been concerned about these impacts. But, we hope that by showing how even common abundance species like Acadian flycatchers can be threatened, policy makers will understand the risks facing our natural resources.