Dickcissel Invasion

Holy cow there are a lot of dickcissels in my neck fo the woods this year. Last year on my surveys I had one dickcissel pair, this year, I'm practically tripping over them. They are by far the most abundant bird outside of red-winged blackbirds on those same survey routes. One of my final duties at the park service was a banding program with Avian Images (and for those who missed it, one of my freelance clients hired me full time and I'm now an Avian Field Ecologist with Westwood Professional Services). The banding program was at Bruce Vento Nature Sanctuary and we even found a breeding pair of dickcissel there.

The birds have been noticed here in Minnesota and Wisconsin and a challenge has been issued to try and document them in every county. Checking out dickcissel information online, this is par for the course for this species on the outer edges of its breeding range. According to Birds of North America Online:

"...this species is notorious for regular seasonal movements within its primary breeding range and for irregular movements outside of this core range to breed in surrounding areas where extensive grassland habitat exists. These erratic, semi-nomadic movements result in dramatic year-to-year changes in distribution and abundance, especially in peripheral and sporadically occupied areas."

And Minnesota and Wisconsin definitely fall on the outer edges of the dickcissel range.

I can't help but wonder how an influx of dickcissel works with other species. Do they drive out bobolink and frustrate savannah sparrows?

I did some more poking around on Birds of North America Online and if you don't have a subscription, you should really consider it somtime and read up on your favorite birds.  You never know what little gems you will find in there.  Some of my favorites about dickcissel on BNA include:

"Nothing remarkable about defecation."


"Dickcissels show resource-defense polygyny (Zimmerman 1966b), as do a few other grassland species (Verner and Willson 1966). Polygyny in Dickcissels is not based on a skewed sex ratio, but on spatial heterogeneity in grassland habitat, such that some males hold territories of higher quality and attract more mates than others."

As if the name dickcissel weren't provocative enough.  I wonder if anyone has tried to use the above as an excuse for infidelity? "Really, honey, it meant nothing.  It was just a little resource-defense polygyny, nothing more.  You know how great of property we have? How could I say no?"