In speculating on what contributed to the northward expansion of Black
Vultures, I wondered if the creation of the interstate highway system
during the 1950s and 60s, with its resultant increase in road kills of
large animals might have played a significant role. So I browsed the
internet for research...Some of the sources reference different
decades in which the expansion began, which makes my hypothesis more
tenuous. However, this abstract from JSTOR sets the time about right
for the construction of such major interstate highways as I-95...a
relative straight-shot from Florida and Georgia, the historic
northerly range of Black Vultures, to New England. The article also
draws a correlation between the vulture's expansion and an increase in
White-Tailed Deer population in the east.
Interesting stuff...and, as usual, it all leads back to changes we have wrought.
Here are some of the other webpages I found: