Effect Of Global Warming Local Habitat

Shifts in Winter Distribution in Birds: Effects of Global Warming and Local Habitat Change.
As global warming intensified toward the end of the 20th century, there was a northward shift in winter ranges of bird species in Cape Cod, Massachusetts, USA. These pole-ward shifts were related to local increases in minimum winter temperatures and global temperature anomalies. This evidence and other recent results, suggests that during the last two decades global warming has led to massive and widespread biogeographic shifts with potentially major ecological and human consequences.
The evidence of such global and local changes is compelling, raising question whether these changes are sufficient to affect organisms and whether globally-driven changes can overwhelm local changes from other sources. In this paper, we use long-term bird censuses to evaluate the relative the relative effects of globally-driven increases in winter temperature patterns, and of local changes in the habitats, on assemblages of birds overwintering on Cape Cod, Massachusetts, USA.
One of the organizations associated with the bird distribution in winter; The Cape Cod Christmas Bird Count has come up statistics over a period of time. The well-honed identification ability of these skilled observers guarantees that species counts are a robust aspect of these censuses. The censuses also report numbers of each species, but these values are not as consistently taken as the species identification. To evaluate the relative effect of global warming trends, we hypothesized, based on previous results, that the winter distribution ranges may be controlled by the cold extremes of temperature regimes. Thus we obtained temperatures that occurred annually from October to February from the National Weather Service.
If warming was biologically meaningful, we would find that southern species sensitive to cold would extend their winter-range pole-ward during the warming period, and that species with more northern ranges might be able to survive winter farther north.
The number of bird species found in the Cape Code census increased from the 1930's through the 20th century. Some of the increase is said to be as a result of changes in observation procedures, some might be owing to global atmospheric changes and some to local habitats.
To sort out effects of climatic warming from effects of differences in census procedures, they used the internal comparison, calculating numbers of species with southern distributions relative to those with the northern distribution for each year of the record. There was a clear increase from 2.5 to 5

Posted by L.S Mustapher