HI: It has always been curious why the Western Kingbirds leaves Colorado so abruptly at the end of August, beginning of September, after which they are quite scarce. One obvious reason is that Colorado’s insect population rapidly diminishes. Recently its become known that the Western Kingbird fits a pattern shared by other western songbirds in that they travel to an area described as the “Mexican monsoon” area which in this country includes southern New Mexico eastern Arizona. At this time of year this monsoonal region is rich in insect life where the kingbird can obtain the necessary protein needed to replace many of its now year old feathers. What is also interesting is that adults leave Colorado much earlier than juveniles where by the end of July beginning of August they have started to move out and by mid August most of the Western Kingbirds remaining in Colorado are supposedly juveniles. For more information in this phenomenon see Auk, April 2009.
This summer Colorado has experienced an unusual amount of moisture, perhaps even historical amounts, so it will be most interesting to see come the end of August if Colorado’s Western Kingbird population will linger longer than usual, assuming the more moisture-insect ratio is in place or will they instinctively disregard this weather anomaly and move south anyways. Lets all keep our eyes open after Labor Day and see how many Western Kingbirds we can tally up. Bob Righter Denver CO --~--~---------~--~----~------------~-------~--~----~ Colorado County Birding: http://www.coloradocountybirding.com/ You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.as/group/cobirds?hl=en -~----------~----~----~----~------~----~------~--~---
