Welcome to the Kirtland's Warbler GeoTrail (KWGT). This trail will take you in a loop in central Northern Michigan through the Jack Pine ecosystem, breeding home of the Kirtland's Warbler. This tour takes you to a total of 25 caches with an amazing trackable geocoin as a reward. The KWGT Passport can be downloaded here: https://f81c572e-1d95-4026-befc-8c60f69cbcd9.filesusr.com/ugd/31e003_41b2f3aa918442e8b08c880e746e6946.pdf
Most Kirtland’s Warblers arrive on their Bahamian wintering grounds in early-October and leave for the breeding grounds in late-April. Kirtland’s Warblers eat primarily fruit in the winter, with insects, mostly eaten from the ground, making up the remainder of their diet. They are known to consume fruit from 10 different species with the majority consisting of wild sage, snowberry, and black torch. Unlike establishing summer breeding territories, Kirtland’s move around in the winter in response to fruit availability. Individuals do tend to return to the same wintering sites every year though.
Studies have shown that higher levels of March rain in The Bahamas, positively influence adult male Kirtland’s survivorship in later seasons, most likely due to increased fruit production.
Cache
To the west of a cache a colleague and I were trying to catch a Kirtland’s that was banded in The Bahamas the previous winter that we named Triple Yellow, because of the 3 yellow bands on its legs. The capture procedure is relatively simple. Locate the singing male, set up a net nearby, place a plastic lemon in a tree, then play a Kirtland’s Warbler song. The Kirtland’s hears a strange male in his territory, comes to investigate, sees the plastic lemon (thinking it is the yellow breast of the intruding male), then proceeds to chase away the “intruder” and flies into the net. This time however the bird came in so fast it bounced off the net like a trampoline. After that, the bird new the net was there and went around and over without ever getting caught. We tried throwing the lemon to each other as sometimes the movement makes the bird less careful. Not this time. We even set up a triangle of net, but the bird outwitted us. We tried again the next week, but the bird was too smart for us.