About 130 species of birds nested in Cook County in the summer of 1992. The dry weather of early summer made it a bad year for wetland species, but populations of some of our forest birds were up.
Our most common bird was the ring-billed gull, with more than 11,000 observed. Most of those were from the colony at Lake Calumet, where an estimated 5,000 pairs nested. Starlings took second with 3,599 individuals, and robins were third with 2,561.
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These numbers have to be approached with caution. One of the nagging problems all bird counters face is how to compare species numbers. Ring-billed gulls are large birds that prefer to hang out in open areas, where they can be easily counted. Robins and starlings, while smaller, are quite bold and noisy and therefore easy to count. But the bird world is also full of skulkers–rails, cuckoos, wrens–that are very easy to miss.
A short-term shift in population numbers probably doesn’t mean much. It could well be that a rainy winter and spring would create a major rebound in 1993. However, several dry years in a row could reduce the breeding stock to the point that recovery might take a long time.
The slight improvement in the number of forest birds is also heartening. Many of these birds are neotropical migrants, spending the summer here and the winter in the forests of Mexico, Central and South America, or the West Indies. Practically every species of neotropical migrant has suffered population declines over the past 25 years–some so drastic that we have reason to fear for their continued survival as species.
Scarlet tanagers were discovered at 18 locations, and as many as 33 pairs may have nested. No summer tanagers were reported, but this is a southern species that only occasionally nests this far north.
