North American birds that feed on flying insects are experiencing steep population declines, particularly long-distance migratory populations in the northern breeding range. We determine, for the first time, the level of migratory connectivity across the range of a songbird using direct tracking of individuals, and test whether declining northern populations have higher exposure to agricultural...

As a measure of cold hardiness, we tested the supercooling points or freezing temperatures of individual hemlock woolly adelgids (Adelges tsugae Annand) collected from 15 locations across the north to south range of the adelgid in eastern North America at different times during two winters. Adelgids from the northern interior locations with USDA hardiness zones of 5B–6B had lower supercooling p...

Each year, millions of monarch butterflies (Danaus plexippus) migrate up to 3000 km from their overwintering grounds in central Mexico to breed in eastern North America. Malcolm et al. (1993) articulated two non-mutually exclusive hypotheses to explain how Monarchs re-colonize North America each spring. The 'successive brood' hypothesis proposes that monarchs migrate from Mexico to the Gulf Coa...

—We compared roost site characteristics of the Indiana bat (Myotis sodalis) and northern bat (M. septentrionalis), which form maternity colonies in cavities and beneath bark of dead (snags) and living trees in eastern North American forests. We used published data (n 5 28 sources; n 5 1145 roost trees) from studies completed where the distributions of the two species overlap and evaluated a sui...

Examination of temperature variations over the past century for Europe and the Arctic from northern Norway to Siberia suggests that variations in the North Atlantic Oscillation are associated with an increase in oceanicity in certain maritime regions. A southward depression of the tree line in favour of wet heaths, bogs and wetland tundra communities is also observed in northern oceanic environ...

Changes in tree species distributions are a potential impact of climate change on forest ecosystems. The examination of tree species shifts in forests of the eastern United States largely has been limited to simulation activities due to a lack of consistent, long-term forest inventory datasets. The goal of this study was to compare current geographic distributions of tree seedlings (trees with ...

Previous studies propose that the Yangtze River is the geographic boundary separating northern and southern Chinese populations. In order to test this hypothesis, 19 Neolithic and 15 Modern human cranial samples from north of the QinlingMountain Range, south of the Yangtze River and in between were chosen for morphometric analysis. Our results indicate that cranial variation exists in Holocene ...

We present a model in which monitoring costs determine firms’ outsourcing and offshoring decisions. We predict that the most productive firms outsource in the South, while the least productive produce in-house in the North. Within the range of intermediate productivities, firms with lower productivity outsource in the North, and those with higher productivity perform in-house production in the ...

[1] We have analyzed the mean climate response pattern following large tropical volcanic eruptions back to the beginning of the 17th century using a combination of proxybased reconstructions and modern instrumental records of cold-season surface air temperature. Warm anomalies occur throughout northern Eurasia, while cool anomalies cover northern Africa and the Middle East, extending all the wa...