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Forest Birds

Climate Change Indicator

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Young forest and shrubland birds are on the decline.

The population trend of songbird species that typically inhabit mature forests has increased over the last 35 years while the population trend of songbird species that typically inhabit forests that are young or dominated by shrubby vegetation, sometimes known as "shrublands", has declined over the last 35 years. As the amount of young forest and shrubland habitat has declined in Connecticut, so have the wildlife species that depend on it. However, the trend for both songbird species groups has generally declined since 2004. Most of the mature-forest bird species are affected greatly by forest fragmentation. Predators, invasive species, overpopulating deer, human activities and other intrusions into the forests cause nesting success to falter. The true forest birds, those that are not adapted to disturbed roadside or suburban habitat, will succeed in the long term only in forests that are not fragmented (i.e., core forests). Nationally, it is estimated that there has been a net loss of 2.9 billion breeding birds since 1970. It is also estimated that approximately 63.5 percent of Eastern forest avifauna, which is comprised of 63 species, are in decline.63

Historic data indicate that the composition of Connecticut's songbird population is changing. Over the last 35 years, the trend for songbirds that prefer warmer climates is increasing, while the trend for cold-adapted songbird species is declining, based on the CEQ index. The CEQ index is used to assess the presence and abundance of a total of eighteen warm-climate adapted and cold-climate adapted songbird species.64

Goal: The goal for a variety of landbird species identified in the Partners in Flight Landbird Conservation Plan 2016 is to prevent further decline, stabilize populations in the short-term, and then reclaim a portion of their populations within 30 years. 

Technical Notes: *The Council calculates index values (using advice from statistics experts) to show the combined population trends of several species (for mature forest birds: Hairy Woodpecker, Wood Thrush, Eastern Wood-Pewee, Red-eyed Vireo, Scarlet Tanager, Black-and-white Warbler, Veery, Ovenbird; for bird species that typically inhabit forests that are young or dominated by shrubby vegetation: American Redstart, Blue-winged Warbler, Chestnut-sided Warbler, Eastern Towhee, and Yellow Warbler). Survey data were not available for 2020.


63 Rosenberg et al.,2019, “Decline of the North American avifauna”; www.birds.cornell.edu/home/wp-content/uploads/2019/09/DECLINE-OF-NORTH-AMERICAN-AVIFAUNA-SCIENCE-2019.pdf.

64 USGS, Eastern Ecological Science Center, North American Breeding Bird Survey, accessed 10-20-2023; www.pwrc.usgs.gov/bbs/.