Red Crossbills, Pine Siskins - Pueblo

[Leon Bright]

COBirders--  As I reported several days ago, Red Crossbills are visiting my back yard regularly, ranging from four to seven birds at a time.  It’s odd that they would stick around after not having been here before during the 47 years we have lived here.  Also, the flock of 12 to 15 Pine Siskins have been snarfing Niger (aka nijer, thistle) seed continuously for about six weeks, much longer than this species has stayed before.  Why would these irruptive species stick around this year?  Soon I will be off to the mountains to check on the cone crop, related to the crossbills.  Could the drought be the cause of the siskins’ extended visit?

Leon Bright, Pueblo (city/county)

[DAVID A LEATHERMAN]

Leon et al,

Cody Porter, crossbill student at U of WY, reported to me last fall he had observed a general failure of essentially all conifer cone crops in the mountains of WY last year.  I suspect a similar thing happened in CO since such large phenomena across tree species tend to be regional.  That probably explains the major incursion of Red Crossbills that included at least two Types (2 which is ponderosa pine dependent, and 4 which is Douglas-fir dependent) into lower elevations, including the Eastern Plains of CO and beyond.  Since cone crops are irregular to start with and take years to produce, I can see why the crossbills that were doing well on local, low-elevation resources would linger until now.

As for siskins, I don't know how long it has been going on but they have nested for one cycle in Lamar in late spring-early summer for several years.  My theory is that the massive wild sunflower crop on the plains most winters, followed by abundant Siberian elm and dandelion seed in April, allows them to do well out there and it is cool enough in spruce-populated cemeteries out East to allow them to pull off the first brood.  I also think they move to the cooler mountains in summer (June?) for brood #2.

That's my take on your observations/questions.

Dave Leatherman

Fort Collins

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From: cob...@googlegroups.com <cob...@googlegroups.com> on behalf of Leon Bright <urr...@comcast.net>
Sent: Thursday, May 17, 2018 9:14 AM
To: Cobirds
Subject: [cobirds] Red Crossbills, Pine Siskins - Pueblo

 

COBirders--  As I reported several days ago, Red Crossbills are visiting my back yard regularly, ranging from four to seven birds at a time.  It’s odd that they would stick around after not having been here before during the 47 years we have lived here.  Also, the flock of 12 to 15 Pine Siskins have been snarfing Niger (aka nijer, thistle) seed continuously for about six weeks, much longer than this species has stayed before.  Why would these irruptive species stick around this year?  Soon I will be off to the mountains to check on the cone crop, related to the crossbills.  Could the drought be the cause of the siskins’ extended visit?

Leon Bright, Pueblo (city/county)

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[Cody Porter]

I'll second what Dave said.

I talked to folks and/or visited places in WY, CO, UT, and MT last fall and couldn't find any good cone crops -- there really seems to have been a massive failure of cone crops across much of the west. I've been amazed at the extent to which type 2 and 4 have dispersed this year. Currently, there is a big concentration of both types in the red and jack pine forests of the upper Great Lakes region. Folks in my hometown in southern Michigan have seen more type 2 than I have this winter!

Initially, I suspected that a lot of type 2 would stick around and try to eek out an existence on lodgepole pine, which basically always has a good cone crop, given that many trees are serotinous and thus retain cones with seeds until a fire occurs. After all, type 5 (the second most common type in our region) is a lodgepole pine specialist, and has a similar bill size to type 2, so why wouldn't a bunch of type 2 stick around? However, that really does not seem to have happened -- the few type 2 that did stick around this year have really been hitting feeders hard and have been doing so for much of the winter (look at the enhanced media reports of crossbills in eBird throughout the Rockies -- almost every time the birds have been identified as type 2, they are on feeders, not conifers). A not insignificant number of birds further out on the plains have even taken to feeding on the sunflower seeds Dave mentioned.

So why did this happen? Why didn't type 2 simply opt to hang out in lodgepole pine all winter, instead of traveling well over 1,000 miles to Wisconsin, spending the winter acting like goldfinches and siskins in Oklahoma, or hanging out at feeders along the Front Range? As the movement of crossbills was really getting underway in the fall, I gathered some data on type 2 that were feeding on lodgepole pine here in the Laramie Range. On average, type 2 birds were extracting seeds at a rate 30% lower than type 5 feeding at the same time/place. It's not easy to make a living in a cold, high elevation pine forest with short day lengths when you're competing for food with a close relative that has a 30% advantage. The bill differences between most call types may be small, but they really do make a huge difference when it comes to their ability to feed on different conifers.

I don't have much to say about siskins, except that I find Dave's observations fascinating and will be emailing him soon about that. However, one thing struck me this winter compared to last year. Throughout the high elevations of the Rockies last winter, there was an excellent cone crop of blue and Engelmann spruce, which siskins readily feed on. At the time, I was doing fieldwork on crossbills in the Snowy Range west of Laramie. By February 13, large numbers of siskins had returned to the Snowies and were singing and courting like crazy. This year, in the absence of such a bountiful cone crop, the first siskins appeared on March 29, at a feeder in Laramie, and they didn't show up in the mountains until much later.

And before I forget, I'd be very appreciative if you'd email me about the cone crops in your area, Leon. The situation is not looking terribly good in the Laramie Range this year.

Good birding,
Cody Porter
Laramie, WY

[David Steingraeber]

I'll add my $0.02.  We live just W of Horsetooth Reservoir, in ponderosa pines.  The big snowstorm that hit us exactly one year ago destroyed virtually all the male (pollen) cones just as they were maturing and getting ready to release their pollen, and I suspect that lack of successful pollination may have contributed to the failure & abortion of young female/seed cones last year, at least locally.  Young female cones were present on the trees around us last year around the time of the storm, but +/- all of them aborted.  (Had pollination been successful, those cones would have grown in size and still be present on trees, with their rudimentary seeds completing their development this summer, and cones opening to release mature seeds later in the summer.)  The trees around us have just begun to show this year's female cones, and the male cones are getting ready to release pollen.  I've noticed (anecdotally) through the years that pollination success at our house often seems weather-dependent -- if we get hit with prolonged rain or snow right when the male cones are getting ready to release pollen, there's little to no pollen deposition, and subsequently low seed set. 

At the present time, we still have a sizeable flock (20-40 or so) of Type 2 Red Crossbills hanging out in the trees around us and regularly visiting our feeders.  When they've shown up at our house over the past 30 years, they've only gone to feeders with (black oil) sunflower "seeds" (fruits, actually); in the past few months, however, they've also (for the first time) been feeding regularly at  a niger feeder.  I was surprised to see them go for the niger, and wonder if others have seen them feed on niger, or other such small seeds/fruits.  I haven't been able to find any references documenting their feeding on niger, and wonder whether its inclusion in their diet might be related to a lack of other, larger and more preferable food items. 

Dave Steingraeber
Larimer County, W of Horsetooth Reservoir

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[ca...@ecentral.com]

I live at 7700 ft between Conifer and Evergreen, and, atypically for the eight years I've lived here, this year I've had PISI regularly throughout the winter.  What has surprised me even more is that I anticipated that they would move on to higher elevations (or lower elevations, as Dave suggests) once we were getting into more springlike weather.  However, in the past two weeks, the opposite has happened.  Currently, I regularly have 25-30 PISI on a daily basis, and following our one somewhat significant snow event in early May there were about 50 around for a couple of days.  They tend to be feeding voraciously, and seem to be relying on my feeders as a significant resource.  I take my feeders in every night, and they and the BTHU are always waiting for me to emerge at the crack of dawn.  I get intermittent visits from 6-12 RECR, but they are not the daily swarm that the PISI are.

Chuck Aid

Evergreen, CO