Professor of Biosciences Herb Wilson researched whether or not birds arrive earlier in the spring now than they did 100 years ago, as he supposed they would. What he found, however, is that there is no significant change in arrival dates for most birds, but 20 species actually seem to arrive quite a bit later than they did around the turn of the 20th century.
Wilson sees two possible explanations: First, the amount of forest in Maine is much greater than it was in 1900, when farmland was more extensive, and as a result, habitat for some birds that seem to be arriving later was likely more abundant then than now, meaning the chances of seeing an early-arriving bird were higher 100 years ago. Second, birders of the early 1900s “were likely more in tune with nature than we are. Outside on foot or on horse-drawn carriages, these observers would be less likely to miss a first arrival.”