Ecology and Vulnerability

Eastern Meadowlark

Background
The eastern meadowlark is a bird that breeds from New Brunswick and central Ontario to Florida and northern Mexico and winters as far north as southern New England and central New York. This species is sedentary across most of its range, but northern breeders make short distance migrations, and some individuals migrate upwards of 1000km/621mi ⁵. Meadowlarks breed primarily in native grasslands, pastures, and savannas with adequate grass and litter cover, and secondarily in human-made grasslands such as hay and alfalfa fields, orchards, golf courses, reclaimed strip mines, airports, and shrubby overgrown fields ^5,8. They winter in similar habitats and marshes and are limited by temperatures ⁵.

The eastern meadowlark has experienced a range-wide decline of 72% in the last four decades ⁹ - nearly 2% a year. Although this decline has occurred throughout its entire range, Breeding Bird Survey data indicates that the highest rates of decline occurred in urbanized northeastern states, including Massachusetts ⁶. Population declines are linked to loss of grassland habitat due to urbanization and agriculture ⁵, disturbance and mortality from livestock and mowing, and pesticide use in agricultural landscapes ⁹. The eastern meadowlark has shown evidence of area sensitivity (i.e only present in larger habitat patches) in some studies ⁴, so habitat fragmentation could also be of concern.

Climate Impacts
Changing precipitation and winter temperatures could have large effects on grassland bird populations. One study found that spring densities of Baird's sparrows (Ammodramus bairdii) were negatively related to the previous winter's snowfall, whereas grasshopper sparrow (Ammodramus savannarum) densities were positively related to May precipitation ¹.  Climate appears to drive the abundance of some grassland bird species, including the grasshopper sparrow, bobolink (Dolichonyx oryzivorus), Henslow's sparrow (A. henslowii), sedge wren (Cistothorus platensis), and upland sandpiper (Bartramia longicauda) ⁷.  Moreover, a study of the effect of a North Dakota drought on grassland birds showed a decline in species richness and abundance, with negative (although primarily short-term) effects on nearly all species studied ³ . Winter mortality from sudden and severe cold snaps has also been reported ⁵. This implies that changes in winter temperatures and in severity of storms may also influence Eastern Meadowlark.

Eastern meadowlark populations may also benefit from climate change. Models of future distribution considering habitat and climate changes predicted that landscape capability (suitable climate and habitat) for the eastern meadowlark would increase by 17% by 2080 ².