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Why the Mallard Might Move North

Audubon’s Chief Scientist explains how even common birds could be affected by a change of a few degrees.

Mallards are widespread and have proven to be resilient species. Over a century ago, agriculture and development claimed nearly all of the wetlands these birds call home. Mallards and other waterfowl species were in severe decline. Hunters, NGOs and government agencies worked together to secure and restore wetlands across North America. The recovery of our waterfowl is an important conservation milestone: The rebound proved that birds respond well to restored habitat and can recover from serious population declines.

Now Mallards* are again at risk. The Audubon Climate Report lists it as one of 314 species threatened by climate change. Our models show that the climate conditions these birds need during the summer months will be harder and harder to find in the lower 48 states. As a result, Mallards are projected to lose up to 75 percent of their current summer range by 2080.

According to the report, in the next few decades Americans looking for Mallards in the summer may have to head to Canada:

When Audubon launched its Climate Report, a biologist in Canada remarked that our projections of Mallards in danger were “nonsensical”. The argument goes something like this: The bird is already widespread over a large swath of geographic area. If it can handle the temperature difference between Arizona and Maine, how much influence could a few degrees of global warming have? 

This is an important issue because it seems like common sense that a widespread species should be able to cope. Yet, even widespread species that seem well adapted to varying conditions can decline very quickly in response to abrupt changes in climate. This is happening right now for Mallards in California. This year, the California Department of Fish and Wildlife found that Mallard populations had dropped 20 percent since 2013. Aerial surveys have been conducted for years, and this was the largest decline ever reported.

California waterfowl biologists attribute the Mallard decline to habitat quality, which in turn is caused by the severe drought the state has suffered over the last three years. Mallards don’t seem to be adjusting well, though other waterfowl species experiencing the same drought in the same places did not decline. This underscores the complexity of response different, but related, species have to the same environmental conditions.

I won’t be surprised if the Mallards rebound in the coming years if the drought recedes. But, we should also be watching closely to see if the drought was an anomaly or the new normal. There is currently some debate as to whether the drought in California is climate-change caused or not (NOAA has suggested it is not). But whatever the final verdict on that, this example shows that species can, and do, respond rapidly to abrupt change in environmental conditions even if they are widespread.

Models can tell us where to focus our concern and which species are likely to need the most help. But in the end, we need to let birds tell which are most susceptible to climate change and which will be more resilient than expected. Birds are great to study because they are so easy to observe and we have a wealth of data to compare to any future changes.  Nature is full of surprises and shows that when given half a chance it can respond quickly.

*Science Note: By Mallards, we’re referring to wild, migratory populations, not birds that have hybridized with domestic duck populations and often permanently reside in urban or suburban parks, lakes, and golf courses. 

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