Interesting discussion. A couple of weeks ago I had a sighting at Prewitt that got my attention (and earned me a flag from eBird): nine Cassin’s lined up together on a fence (with one western). This had me thinking about group migration by the species.
Norm Lewis Lakewood (but currently in Montrose) Sent from my iPhone > On Oct 4, 2017, at 5:10 PM, DAVID A LEATHERMAN <[email protected]> wrote: > > David and all, > > The map in Sibley is not accurate. There are breeding populations in eastern > Montana, southwestern SD, eastern WY and western Nebraska (Wildcat Hills, > etc.). Birds of Nebraska by Sharpe et al list them as "fairly common > breeders in the Panhandle". Birds of Wyoming by Faulkner reports a count of > 31 at Pine Bluffs on 3September2000. Most of these areas have open grown > ponderosa pine which looks a lot like the eastern Black Forest in Elbert and > that is where I always figured our late September-early October Cassin's at > places like the Pawnee Grasslands and Fort Collins come from. There is also > a patch of aberrant limber pine just south of where CO-NE-WY come together in > CO that is private but may also support a breeding population. Cassin's > Kingbirds show up on the northeastern plains and along the Front Range pretty > much every year about this time of year (later than Eastern and Westerns). > There seems to be more of them this year than most, but then, there are a lot > more birders than there used to be. I think the Cassin's Kingbirds are > coming from somewhere north of us. > > > Dave Leatherman > > Fort Collins > > > From: [email protected] <[email protected]> on behalf of David > Suddjian <[email protected]> > Sent: Wednesday, October 4, 2017 3:45 PM > To: Colorado Birds > Subject: [cobirds] Cassin's Kingbird origins > > I'll suggest an answer to my own question about where the recent Cassin's > Kingbirds are coming from. I suggest this is a northward movement, similar to > the "reverse" migration of Tropical Kingbirds in California, and now one from > CO. Looking at eBird patterns for Wyoming and Nebraska to the north, and CO > counties that are north of or adjacent to the main CO breeding range of > Cassin's (e.g., Jefferon, Boulder, Larimer, Weld, Adams), there is an > increased frequency of occurrence in September that is not a continuation of > a late summer presence but seems to result from migrants moving during > September (and into early October). Since there is not really a pool of birds > to the north during September or late August, it seems to me most likely that > the Cassin's we are finding over the last few weeks have moved north in a > "reverse" pattern... maybe from afar away. > > Maybe this pattern is already obvious to others or established? Thoughts? > > David Suddjian > Ken Caryl Valley > Littleton, CO > -- > You received this message because you are subscribed to the Google Groups > "Colorado Birds" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/cobirds/CAGj6Roodmw54-HCRxnMORb56DB0KVt-QJeZJ2%2B-4wQC09auWDA%40mail.gmail.com. > For more options, visit https://groups.google.com/d/optout. > -- > You received this message because you are subscribed to the Google Groups > "Colorado Birds" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/cobirds/SN1PR0601MB16156464D7828D9C63C7BAE5C1730%40SN1PR0601MB1615.namprd06.prod.outlook.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/cobirds/9CEF3A45-DDEF-4A52-8F97-45A8FBAEE254%40aol.com. For more options, visit https://groups.google.com/d/optout.
