The Irruption of 2020-2021

I don’t know about you but the word irruption doesn’t conjure up a positive image to me. As I sit here at my desk a former President is being impeached after the January 6th Capital riot, Covid is surging in my state of Virginia, Vaccine distribution is still months off, and I've been quarantined from family and friends for almost a full year. With all that has gone on in the past year an irruption would not be totally welcome. But I am talking about a different irruption - the irruption of birds. Ornithologists are referring to it as the Winter Finch Irruption of 2020-21.

 

Purple Finch

Pause for a moment amidst all the stresses of the day and take a look out of your window. If you feed the birds or watch the shrubs and bushes you will notice something unusual going on that occurs in our area every 3-4 years. You will see all your familiar winter birds, like the beautiful Cardinals, the perky Carolina Wrens and the colorful Bluebirds but this year you will see masses of Finch-like birds invading your yard.  Such species as House Finches with their splash of red, Pine Siskins, Red Polls, Purple finches, Juncos,  and the beautiful Red Breasted Nuthatch. These birds are visiting us this winter in far greater numbers than seen in the last 20 years. It's being referred to as a "Super Irruption". Slightly north of us the States are experiencing an influx of the beautiful Evening Grosbeaks, also a seed eater.

 

Red Breasted Nuthatch

The answer for the increase lies in the cold north. Ron Pittway, a noted Canadian ornithologist from Toronto has studied finches for many years as an employee of the Algonquin Provincial Park. He started publishing his annual count in 1999. No question, these birds of the north are moving south, as far as North Carolina in what has been labeled a “Finch Irruption”.

 

                                                             White Breasted Nuthatch

These northern small perching birds are moving south due to a scarcity of food stuffs that are part of their routine diet in the boreal forests of Canada.   Finches and their relatives prefer pine nuts found in conifers, which are also found here in our Piedmont area. Seeds at backyard feeders are an welcome buffet.

Pine Siskin

An interesting phenomenon has been studied which identifies a cyclical relationship between trees and seed-eaters like birds and squirrels. The relationship seems almost supernatural at first glance as if the trees and squirrels are communicating with each other. Who better to know a tree than a squirrel? 

 

Grey Squirrels -"Sciurus Pain-in-necksis"

Here’s my condensed version of what is going on. Trees produce an abundance of seeds in a given year in order to reproduce. In response birds and squirrel populations increase with the abundance of food in that year, inhibiting the trees ability to reproduce. The trees respond in mass by not producing as many seeds in the next year. The squirrels in particular reduce the size of their litters due to the shortage of food. The following year the trees rebound producing an abundance of seeds in order to reproduce amongst the smaller squirrel population.  The seed-eating birds head south in the lean years and THAT in part is what we are experiencing here this winter. And thus, the cycle continues. This year there is a greater scarcity of seeds in the north. This cycle of "Boom-Bust" may also answer my question as to why only in certain years there are acorns on the ground everywhere causing me to “roller-skate” on my garden path.

Dark -Eyed Junco

 

Trees and Squirrels communicating? Sounds like the stuff of science fiction, but this year…I’ll believe anything. Search the Cornell University E-Bird site for more information. Wonder in the cycle of living systems and keep those bird feeders full. How many of these finch-like birds do you see?

 

House Finch

Goldfinch in Winter Plumage