Date: 11/3/20 5:57 am From: Jesse Ellis <calocitta8...> Subject: Re: [ia-bird] Evening Grosbeaks in Iowa
Jim and All-
The period you refer to here in the 70s and 80s corresponds, if I recall correctly, to a peak of both spruce budworm and of Evening Grosbeak population in the boreal forests north of here. Spruce Budworm follows a boom and bust cycle feeding on balsam fir, and there were many records of EVGR across Minnesota at that time as well. Once the budworms died off a bit, the grosbeaks dwindled as well (I think some spruce/fir specialist warblers did too? Cape May, for instance?).
Now, in northern MN and S Ontario, budworms are doing very well again and in the past two years in northern MN at the Coe College Wilderness Field Station I have had regular detections of Evening Grosbeak in the summer, suggesting local breeding (we had a juvie show up two summers ago, the first detection at the station since a huge flock was present in... the mid 80s.)
The movements of many different winter finches this year (siskins, crossbills, possibly redpolls and even maybe Pine Grosbeaks, out east at least) suggest that tree crops were bad. I would guess that high reproduction and poor winter food sources have combined to push them out of their regular winter range.
Jesse Ellis Coe College Cedar Rapids
On Sun, Nov 1, 2020 at 2:56 PM Dinsmore, James J <oldcoot...> wrote:
> Birders > > The recent flurry of reports of Evening Grosbeaks in Iowa and a discussion > I had this morning with son Steve reminded me that I had written a paper on > that subject some years ago. The paper, "Evening Grosbeaks in Iowa: An > avian mystery" appeared in the now defunct IOU News, volume 26, no 1, pp > 6-7 published in 2010. Some of you may still have copies of that issue. The > paper pointed out that the species had been a fairly regular but rare > winter bird in Iowa in the 1970s and 1980s and was seen on CBCs all but > three years from 1970-1990 but then virtually disappeared from Iowa. The > last report of one was in Fairfield in 1998. Since 2010, there have been a > few reports in Iowa but it has remained a rare bird here with no real > explanation for its disappearance. My only personal experience with the > species in Iowa was a few seen in Ames on a class field trip in March 1978. > One of the lucky observers that day is now an (unnamed) active > birder/member of the IOU. > > With the advent of eBird and so many more people now looking at birds, it > will be interesting to see if there are more observations in Iowa and > elsewhere of this very different looking species that often visits bird > feeders. Keep watching. > > jim dinsmore > The Villages, FL > > -- > You received this message because you are subscribed to the Google Groups > "IA-BIRD" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to ia-bird+<unsubscribe...> > To view this discussion on the web visit > https://groups.google.com/d/msgid/ia-bird/<BN8PR04MB56973F42C5442A3EDE3F95F0AF130...> > <https://groups.google.com/d/msgid/ia-bird/<BN8PR04MB56973F42C5442A3EDE3F95F0AF130...>?utm_medium=email&utm_source=footer> > . >