The National Audubon Society recently released a study of the potential impacts of climate change on the ranges and distribution of more than 600 North American birds. Audubon scientists used hundreds of thousands of citizen-science observations and sophisticated climate models to predict how birds in the U.S. and Canada will react to climate change. The results are alarming. More than half of the species studied will likely suffer significant range contractions and/or need to find suitable habitat in new areas in order to thrive. Approximately 30 species studied will have their “climactic envelope” shrink by more than 99%, meaning they may run out of suitable nesting or wintering areas and run the risk of becoming extinct, including some species regularly found in Connecticut.
This study looked at 18 climactic variables of precipitation and temperature under a host of different climactic scenarios, but this study is only a first step. Many compounding factors, both predictable and unforeseen threaten to make the situation worse. For example, rising sea levels were not yet taken into account in the study, nor were factors such as changes in bloom periods for plants and emergence dates for insect or other prey items.
This is particularly relevant with regard to the potential impacts of these changes on Connecticut’s birds. Pictured above is a Saltmarsh Sparrow, which is among the species most endangered by climate change in North America. For a variety of reasons (mostly stemming from the difficulty of detecting the presence of this species in traditional survey methods), Saltmarsh Sparrows not included as part of this study. Nonetheless, Saltmarsh Sparrows are in deep trouble because of rising sea levels.
Saltmarsh Sparrows only breed in a small sliver of suitable habitat from Maine to Virginia. If you added up the entire suitable nesting habitat in the world for Saltmarsh Sparrows, the area would be smaller than the land area of Connecticut. They nest directly on the ground in the higher (relatively) portions of tidal marsh habitats, making them especially vulnerable to sea level rise. Upon returning to nesting areas in the spring, they attempt to nest immediately, but almost invariably lose their nests to the next high spring tide. The race is then on to re-nest quickly so that their eggs can hatch and chicks grow strong enough to climb up on taller pieces of vegetation before the inevitable return of the next flooding tide. Any shortening of that window between periodic tidal flooding can spell doom for the nestlings.
Researchers from the University of Connecticut and other partners up and down the East Coast are studying this species and finding that it is already suffering poor productivity from the effects of sea level rise. This all is compounded by the limited nesting range of this species. Normally, as sea levels rise, sediment deposition allows marshes to keep pace with rising sea levels and such habitats will migrate landwards as the sea encroaches. Since these sparrows are restricted to one of the most heavily developed areas of coastline in the world. We have also altered the natural flow of rivers, which starves marshes of the sediments they need to grow; these habitats are just not keeping pace. The habitat that this species requires may disappear entirely, but because of the above mentioned shortened window for nesting, Saltmarsh Sparrows may be gone long before the tidal marshes themselves are.
Audubon is a key partner in this ongoing research in the Mid-Atlantic region and was a pioneer in sounding the alarm for this species, an alarm which UCONN researches rose to meet by initiating important research into its distribution, nesting success and strategies to meet the challenges that Saltmarsh Sparrows are facing. We are also working with partners to identify and protect key buffers for the areas most important for this species’ survival and have played a key role in the protection of over 1,000 acres of upland buffers for globally important nesting areas in Connecticut for Saltmarsh Sparrows in the last decade.
To learn more about Audubon’s climate report and what you can do to help, please see:
To learn more about how Connecticut’s birds will be affected, please see the following slides.