Blue Grosbeaks

[DAVID A LEATHERMAN]

I am curious as to whether any one else thinks Blue Grosbeaks are definitely more common in the northeastern quadrant of Colorado than they used to be.  They used to be present in this area back in the 1970s and 1980s but were noteworthy, and very local.  Now I would say they are sort of expected in any decent patch of rural thicket with a few trees, especially in years we have had rain (like this one). 

Like so many southern species that appear to be marching northward, Blue Grosbeak is now part of the normal scene north of I-70 and e of I-25.  Not sure if this is mostly due to climate change or human activities like shelterbelt plantings, or both.  According to the Nebraska and Wyoming books by Sharp et al and Faulkner, respectively, they are statewide in low numbers in NE and very local in WY (no mention of trends, per se).

Also, I am assuming the great majority of CO birds are of the western race, Passerina caerulea infusa.  Do we know if any examples of the other two U.S.-occurring subspecies P. c. caerulea (eastern) or P. c. salicaria (southwestern) have been seen/collected in CO?  And can these be differentiated in the field by sight and/or voice?

Comments?

Dave Leatherman
Fort Collins

[David Wade]

Personally, I have noticed an increase in Blue Grosbeaks around Fort Collins at least. Looking at my ebird sightings I counted 76 birds seen last year among 4 sites I frequent around the Fort. I have sightings in each month from May to September, most coming from Douglass Reservoir a few miles north of Fort Collins. At North Shields Ponds Natural Area, I think a pair nested because, in the same area, I saw a pair in May, none in June (nesting and secretive), a pair in July, then Adults and immatures in Aug. I also had sightings at Running Deer NA and Bobcat Ridge NA. My most interesting sighting was 2 fledglings in the third week of Sept at Douglass Res. They couldn't have been out of the egg for more than a few days. I never saw the parents and  I'm not positive they were Blue Gbeaks, but they had a large grosbeak like bill. Rather late nesting (3rd clutch?) for any passerine, none the less, possible evidence of breeding there too.

I have a few records from Larimer County from 1988 to 1992 and none of those show any Blue Grosbeaks. My first Larimer sighting was is 2011 when I saw one that year. 

David Wade 

Fort Collins,  CO