A project of

Winter Wren

Wren of the Woods

Winter Wren is an unusual wren: its breeding range extends further north than any other North American wren - small numbers of individuals nest regularly in the Yukon and the Northwest Territories - and, unlike most of its relatives, it lives in mature, structurally complex forests.

The State of Winter Wrens

Regionally: Declining

The numbers of Winter Wrens counted during Mountain Birdwatch surveys have been declining since at least 2012. Since 2011, the overall numbers of Winter Wren in our study area have changed by -3.41% per year (95% Bayesian credible interval = -4.19% to -2.62%). This equates to a 24% overall reduction (95% Bayesian credible interval = 19% to 29%). Interestingly, Winter Wren declines have a longitudinal and latitudinal pattern–the declines become less severe as one moves from Maine towards the Catskills of New York. These declines are supported by the North American Breeding Bird Survey results from the last decade within the Atlantic Northern Forest Bird Conservation Region. In both data sets, Winter Wren numbers fluctuate up and down frequently. These fluctuations may be related to severe winter mortality.

The mean (thick, dark orange line) annual estimate of the Winter Wren local population size within the immediate area surrounding ~750 Mountain Birdwatch sampling stations. The vertical orange bars present the 95% Bayesian credible interval (a measure of uncertainty) surrounding those mean annual estimates.

Mean annual population trends (below) for Winter Wren from 2011 through 2019. A red dot indicates strong evidence for a negative trend. An orange dot indicates a likely negative trend. A trend of -2%, for example, indicates that the number of Winter Wrens in our study area has declined by an average of 2% each year from 2011 through 2019.
RegionMean annual trend (%)95% credible interval
All regions combined -3.41(-4.19, -2.62)
New York (state) -2.89(-4.08, -1.70)
New York (Catskills) -1.65(-3.09, 0.00)
New York (Adirondacks) -3.20(-4.60, -1.80)
Vermont -1.74(-3.26, -0.14)
New Hampshire -3.85(-5.04, -2.71)
Maine -5.55(-7.12, -4.01)

Globally: Probably stable

Winter Wren overall population index for Canada and the US. The black line indicates the annual estimate of relative abundance; higher numbers mean more Winter Wrens were counted in that year. Red lines above and below indicate the uncertainty around estimates of relative abundance. Figure provided by the United States Geological Survey.


Data collected by the Breeding Bird Survey indicate that Winter Wren numbers across much or Canada and the U.S. are higher than they were in the 1970s. Since 2000, however, many populations of Winter Wrens appear to have declined.





Opportunities for Conservation

In the northeastern U.S., Winter Wrens are most abundant between 900 and 1200 meters (upper left panel), in areas with high canopy coverage of spruce-fir forests (lower left panel), and at northern latitudes (i.e., Maine, upper right panel) and western longitudes (i.e., New York, lower right panel). The dark lines represent the mean relationship between abundance and the covariate; the lighter colored-areas represent the uncertainty of the mean response (i.e., the 95% Bayesian credible intervals).

The long-term stability of Winter Wren populations suggests that the species is not in need of any immediate or specific conservation intervention. Most importantly, we can continue to provide complex, mature forests that offer safe nesting and wintering habitat. Because of the vulnerability of Winter Wren to harsh winter weather, we should continue monitoring populations, especially given the risk of increasingly volatile and severe winters due to human-caused climate change.

State of Mountain Birds