Tuesday, December 26, 2006

Purple Sandpipers as Merlin Food


Purple Sandpiper at Sheboygan in 2002

This past Sunday, Seth and Noel Cutright witnessed a Merlin chase and capture what they believed to be a Purple Sandpiper at North Point, Sheboygan. Seth reported the observation to the Wisconsin Birding Network, "It was a good sized bird for a Merlin to take." Yeah, that's what I thought, too.

I made the trip up to Sheboygan with Kim and Corey Benton on Saturday and we were fortunate to find 3 Purple Sandpipers (as many as 5 were previously reported). I first spotted them flying over the water by the piers, then they came to rest on the rocky point next to the parking lot. The three birds briefly foraged, but soon went airborne again in favor of a spot further down the beach. We walked over and got excellent looks at them (life birds for both Kim and Corey). These were the first Purple Sandpipers I've seen in nearly 3 years.

The shorebirds were pretty skittish compared to the few other Purple Sandpipers I've seen in the past and recall thinking they would make an obvious target for a Peregrine Falcon. I have to admit I first read Seth's post with a bit of skepticism, as I've generally associated Merlin diet with large insects, rodents and small songbirds...but a shorebird as large as a Purple Sandpiper? I turned to Cornell's Birds of North America on-line for the answer:

"Diet on migration and wintering grounds poorly documented. Early studies based on stomach contents of migrating Merlins showed insects a large proportion of diet (Allen and Peterson 1936). Wintering Merlins feed heavily on various species of small shorebirds in areas where they are abundant; e.g., Least Sandpiper (Calidris minutilla) and Dunlin (C. alpina) each made up nearly 40% of the diet of Merlins wintering at Bolinas Lagoon (Page and Whitacre 1975; Buchanan et al. 1988). Urban wintering Merlins mainly feed on House Sparrows (72% of diet) and Bohemian Waxwings (17%; Warkentin and Oliphant 1990, see also Smith 1978, Servheen 1985). In Venezula (Hilty 2003), follows and feeds on large Dickcissel flocks found in some sections of the llanos (seasonally flooded grasslands)."

If a Merlin (10" in length) can take a Dunlin (8.5"), then it can take a Purple Sandpiper (9"). Fitzmier, you better get up to Sheboygan quick time. Those chubby rock-pipers are gonna be eaten!

Purple Sandpiper image © 2006 Mike McDowell

3 Comments:

At 6:41 AM, Anonymous Ryan Brady said...

Hey Mike,

It's not uncommon for Merlins, especially females, to capture pigeons, although they have trouble transporting them once captured. I've seen this on several occasions. A mid-sized shorebird is no sweat at all. And certainly more bang for the buck than a measly sparrow!

 
At 6:35 AM, Anonymous mon@rch said...

We have noticed that our nesting Merlin’s feed primarily on English Sparrows and European Starlings!

 
At 12:22 PM, Blogger Seth said...

Here is just another note about Merlins vs. Purple Sandpipers. In the book "Raptors of Western North America" by Wheeler, it lists the size as:
Male-length 9-11" and Female-length 11-12"

From the book "The Shorebird Guide" by O'Brien, Crossley, and Karlson, for Purple Sandpiper it list length as 8---8 3/4"
Then for a Dunlin 6 1/2--8 3/4"

So the largest Dunlin can equal the largest Purple Sandpiper in size. So a Merlin either Male or Female should be able to get either one. Also a reminder is that Peregrine Falcons use to be called "Duck Hawks." Some ducks are close to Peregrines in size but I don't think that would stop one from trying to get the other. Part of it just depends on speed and they way the bird can move and hunt. Most likely Merlins would be faster with quicker moves then most Purple Sandpipers.

Also we should remember that most birds of prey hunt the other birds that are slower, or older, or hurt, or have something wrong with them and are for the most part not 100%. This helps keep that species strong if the weaker bird of that species is caught...and for the most part it will take less time and energy for the bird of prey to catch.

So I always love to watch a Merlin or Peregrine hunting...

 

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