We love fat!

Yesterday’s climatic drama here in MN included thunder and lightning (in the winter!), rain, freezing rain, sleet, snow, and then bright sunshine for 5 minutes before more gray drizzle.  There was also a lot of wind, making outdoor activity quite uncomfortable.  The birds visited the feeders frantically early in the morning, perhaps in anticipation of the weather drama soon to hit them. It was entertaining to watch the woodpeckers scramble for access to the suet feeder — I usually never see all four resident species within the space of 10 minutes.

Northern Flicker-

Mr. Yellow-shafted Flicker was first and dominated for a few minutes until he was completely sated and went and sat in a tree to digest his heavy meal.

yellow-shafted flicker

So full of fat now — that’s about 100 calories per gram of suet eaten, and this guy ate a lot!

Hairy Woodpecker

Mrs. Hairy Woodpecker fed noisily, chipping continuously as she warned others to stay away until she had her fill.

Red-bellied Woodpecker-

However, Mrs. Red-bellied Woodpecker was not to be denied access and finally drove Mrs. Hairy off. She vigorously attacked the suet, drilling multiple holes in the block.

Downy Woodpecker-

Finally when everyone else was satisfied, Mr. Downy Woodpecker got his chance, and spent a few minutes cramming big chunks down his gullet.

You’ve probably noticed the order of my suet visitors seemed to be organized by size, and it certainly seems to be the case that smaller birds do yield to larger-bodied ones when both want the same resource.

But the intensity of the feeding activity observed made me wonder if precipitation that day was more of driving force, or was it the drop in temperature??  Do all birds respond the same way to these two climate variables?  Well, it turns out that someone else was interested in these questions, using the data generated by Project Feeder Watch collected from backyard feeders in the northeastern U.S. by the folks at the Cornell Lab of Ornithology.  And some of the results were a little surprising, summarized in the graph below.

Zuckerberg et al. 2011 fig 2

Gray bars next to the species name indicate the extent to which birds might increase their feeder activity in response to decreased temperature. Black bars indicate the feeder activity response to increased precipitation.  Obviously, not all species respond the same way!

According to the authors’ findings, Yellow-bellied Sapsuckers showed the greatest probability of increased feeder activity with decreased temperatures, but the diminutive Downy Woodpecker’s feeding activity did not change with temperature — probably because they are such regular visitors every day anyway.

Red-bellied Woodpeckers are more responsive to temperature changes than Hairy Woodpeckers, even though the two species are very similar in size, and presumably in their daily energy needs.  So, perhaps this reflects differences in the two species’ reliance on backyard feeders for their total food intake?

House Finches and Cardinals are more likely to be seen at feeders when there is marked precipitation, but the House Finches, like Downy Woodpeckers don’t seem to care if it’s colder — just wetter.

It’s amazing what one can learn from observing birds at a feeder.  Do these results jive with what you’ve seen at your bird feeders?

4 thoughts on “We love fat!

  1. I participate in Project FeederWatch and am always amazed at the flurry of activity before the arrival of bad weather. Mr. Red-bellied is the bully at my suet feeder and yes, the Downys are regular visitors, regardless of the weather. I rarely have a Flicker stop by in the winter although the Hairy is an occasional visitor.

      • I’ve been doing this for 7 years now. It’s made me a lot more aware of who’s foraging in the yard.

        The count runs from mid-November through early April – any two consecutive days of the week, amount of time is up to the participant. Over the two days I tally the highest number of each species seen at any one time (no distinction for M or F), high and low daytime temp, precipitation, and snow/ice coverage.

        This is one of Cornell’s Citizen Science Projects. They publish summaries and links to some of the research the data was used in. http://feederwatch.org/

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