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Feb 09 2017

Predicting that next winter finch irruption

Author: DakotaBirder • Discussion: No Comments
Pine Siskin - Spinus pinus

A Pine Siskin, a regular but unpredictable visitor in winter in South Dakota Research shows that southward irruptions of boreal finches such as Pine Siskins may be predicted from recent seasonal climate records.

Not a lot of time this week to blog, as I’ve been in pretty intense meetings all week for work.  However, it was through those meetings that I became aware of this interesting research paper.  Birders are always wondering when that next great “irruption” of boreal bird species will occur.  On occasion, boreal finches such as Common Redpolls, Pine Siskins, and Crossbills will move southward in great numbers from their boreal forest stronghold.  The thought is that such irruptions occur when poor “mast” production occurs, with lower conifer seed numbers than normal.  The birds thus move southward in search of food.

It’s not just boreal finches that are subject to occasional southward irruptions.  One of the greatest birding experiences of my life was during the huge boreal owl irruption into northern Minnesota over a decade ago, when Great Grey Owls and Northern Hawk Owls were seemingly “dripping off the trees”.  Those irruptions are thought to be due to a similar driving force…a loss of a primary food source…with periodic crashes of small rodent populations driving the owls southward in search of food for the winter.

The paper below (click to see it) gives an assessment of climate data to potentially predict when a finch irruption would occur.  The species studied here is the Pine Siskin, but the authors note that it may also apply for other boreal finch species that depend on conifer mast.  Cool study…

More coming next week!  Given I’m still in meetings the rest of the week and have family obligations all weekend, it’s likely the next blog post won’t come until Monday!  Click below for the study…

Predicting finch irruptions with climate information

May 11 2015

Predicting that next invasion of winter finches

Author: DakotaBirder • Discussion: No Comments
Common Redpoll - Acanthis flammea

A Common Redpoll, one of several “northern finch” species that sporadically invade the conterminous U.S. With this study, perhaps those irruptions could be predicted in the future.

It was 2 winters ago that we had an incredible redpoll invasion.  I’d never even had one in my yard before, and we’d lived in South Dakota for 20 years.  However, in the winter of 2013/2014, we had Common Redpolls around for several months.  A real thrill when one, and then another, Hoary Redpoll showed up at my feeders and stayed for a couple of weeks.

Such events are always a surprise, and it’s not just Redpolls.  Both Red and White-winged Crossbills are equally unpredictable winter invaders across the U.S., as are Pine Siskins and Evening Grosbeaks.  It was generally understood that large movements southward in the winter were due to poor seed crops for pines and spruces further north.  A new study from the University of Utah attempts to explain the winter invasions, based on climatic variables. First, the study finds that favorable climate patterns tend to shift across the continent. When one region is favorable to seed production, other parts of the continent are more likely to have unfavorable conditions for seed production, resulting in periodic movements in birds as they key in on areas with the most food resources.

The other climate finding is that it may be possible to predict irruptions to south up to two years in advance!  Seed production itself tends to be correlated with favorable conditions 2 or 3 years PRIOR to the actual growing season.  So, for example, if 2015 has unfavorable climate conditions in much of Canada, it may mean reduced seed production in 2017, resulting an increased likelihood of a southward irruption of northern finches. One of the things I love about birding is the total unpredictability, as you never know what you may see when you head out, but it would be cool to be able to anticipate a great winter finch season.

One final aspect of the work I like…they relied very heavily on eBird data.  A GREAT resource, but one that really isn’t being used for research nearly as much as other, more established monitoring programs like the Breeding Bird Survey.  If found the eBird data to be invaluable for the bird/climate/land-use study I published, and I think you’ll see more papers like this finch study use eBird data in the coming years.

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