Friday, April 22, 2011

The dark side of meadowlarks: an annotated bibliography

Western Meadowlark, Merced National Wildlife Refuge
A ruthless killer. (photo by Chuq Von Rospach)

You might not know it, but meadowlarks are carrion-eating scavengers, egg-eating nest predators, and even cold-blooded killers! I didn't know either, until I stumbled upon a series of articles detailing the full scope of their gruesome taste for blood. I'll get right to the bibliography... 

Terres, J. 1956. Eastern meadowlark eating a traffic-killed bird. Auk 73:289-290.

The first hint of these dark tendencies was revealed in a 1956 article by John Terres of the National Audubon Society. In it he relates a chilling scene of cannibalism that must have made an impression, as it occurred 17 years before the article was published. It was early July 1939, in upstate New York. Along the edge of a well-traveled road, a dead meadowlark is systematically pulled to bits by a live member of its own species. Terres, perhaps too professional to express his presumed horror in anthropomorphic terms, coolly excuses the behavior as simply making nutritional sense. As he put it, "I see no reason why almost any wild songbird might not be inclined to eat meat if it had the opportunity."

Hubbard, J. P. and C. L. Hubbard. 1969. Meadowlarks feeding on road-kills. Wilson Bull. 81:107-108.

Further light was shed on this scavenging (and cannibalistic) tendency one snowy day in December 1967. John and Carrie Hubbard were driving along a lonely desert highway in New Mexico in a blizzard, when they witnessed a curiously macabre scene. They began to notice dead birds along the roadside. Lots of them. Horned larks, mourning doves, lark buntings and meadowlarks, all apparently killed by cars as they foraged in the only snow-free areas around: tire ruts. The Hubbards made their way along this gruesome route, where "bodies littered the highway and roadside," stopping frequently to collect specimens (typical biologists, apparently). Before long they began to get suspicious. At each carcass (including those of meadowlarks) one or more live meadowlarks would often flush. Later examination of meadowlark stomach contents confirmed their suspicions: feathers and bird skin pieces were main components. 

Tyler, J. D. and L. L. Choate. 1990. Opportunistic scavenging by meadowlarks in southwestern Oklahoma. Proc. Okla. Acad. Sci. 70:41-42.

Twenty years later, a similar but even more grizzly scene was witnessed on Interstate 44 in Oklahoma after a massive ice storm. Dead birds (and mammals too) were everywhere, killed in the same manner: struck by cars while scrounging for seeds on ice-free roads. The article by Jack Tyler and Larry Choate of Cameron University reads like an account of a plague or epic natural disaster. The body count included nearly 500 meadowlarks (eastern and western),  over 900 mourning doves, "great numbers" of bobwhites, and mammals including house cats, hispid cotton rats, and cottontails. Throughout this scene of carnage, a mixed flock of eastern and western meadowlarks roamed and feasted on the flesh of mammal and bird alike. There also seemed to be a vicious circle in effect, in which meadowlarks were struck by cars while feasting on road-killed meadowlarks which were struck while feasting on...etc.

Schrick, M. P. 1979. Tree Sparrows killed and eaten by meadowlarks. Bull. Oklahoma Ornithol. Soc. 12:33-34.

Now it's getting serious. I was willing to accept carrion-feeding in meadowlarks, but predation...that was too much to believe. Again the scene is rural Oklahoma during a mid-winter blizzard. Michael Schrick of the Corp of Engineers had been shooting starlings at a bird feeder with a pellet gun (?!) and was shocked when the meadowlarks below the feeder began "pecking at and eating" the corpses. And this despite the piles of seeds he had scattered for them. Imagine his surprise two days later when he witnessed the following. I quote:

  • Park Ranger Wes Masonhall and I saw a meadowlark suddenly walk toward and grab with both feet a Tree Sparrow, a maneuver that obliged the meadowlark to fall to its side while striking its victim
    with its beak. The commotion did not seem to frighten the Tree Sparrows, but it did attract the other meadowlarks, several of which started to peck the captured sparrow. Rivalry developed: one meadowlark, more aggressive than the others, jabbed savagely at the sparrow's captor, forcing
    that bird to release its prey. The aggressor strode off with the dead sparrow in its beak. When it stopped to feed, however, the other meadowlarks put it to flight. Eventually, still carrying the sparrow in its beak, it disappeared in the distance.
    Almost immediately, the vanquished meadowlark caught another sparrow; another free-for-all developed; and the sparrow was killed and eaten. The living sparrows, obviously ravenous, and possibly weakened by starvation, did not seem to realize that the meadowlarks would be predatory.

Wow, that is real drama! Rivalry, vanquishing, victims, starvation, free-for-alls, striding, aggression. It has it all. This turned out to be the first of several accounts indicating that meadowlarks, when pushed to the edge, will kill.

Waters, L. S. 1990. Meadowlarks prey on Pine Siskins and American Goldfinches. Bull. Okla. Ornithol. Soc. 23:7-8.

Bell, P. M. 1990. Eastern Meadowlark predation on American Goldfinches. Bull. Okla. Ornithol. Soc. 23:20-22.

An Oklahoma bird feeder, mid-winter, recent snowfall. Starting to see a pattern. 

Two separate articles by Patrick Bell and Luann Waters published in 1990 not only added significantly to the body count attributable to meadowlarks, but also shed light on their ghoulish methods. For example: "Part of the roof of the finch's skull was gone, as was half the brain." And "another goldfinch had a massive opening in its cranium..." And "bird was killed by pecks to the back of the head and then left intact while the meadowlark returned to the feeder and ate sunflower seeds...Later, the meadowlark came back, ate the brain first..." Aaaaahhh!

Creighton, P. D. and D. K. Porter. 1974. Nest predation and interference by Western Meadowlarks. Auk 91:177-178.

Schaeff, C. and J. Picman. 1988. Destruction of eggs by Western Meadowlarks. Condor 90:935-937.

Picman, J. 1992. Egg destruction by Eastern Meadowlarks. Wilson Bull. 104:520-525.

Say it ain't so. Not only do they kill adults, but they also kill babies. Specifically they have a taste for eggs of horned larks and lark buntings, and even Coturnix quail and clay eggs placed in artificial nests. Presumably, eggs of all ground nesting species would suit their pallets. And nestlings are also fair game, apparently, as Creighton and Porter found a lark bunting chick with "deep puncture wounds in the back and neck" after the nest was "inspected" by a meadowlark.

So, after all is said and done, can we excuse these anthropomorphically distasteful behaviors of eastern and western meadowlarks - namely cannibalism, infanticide, and murder? I say: maybe so. At least on the basis that they seem to occur mainly in extremely harsh circumstances (think "Donner Party"), and primarily in Oklahoma.

Squirrel goiter?

At first glance, this might look like a cute picture of a squirrel loading his cheeks up with acorns. But when I downloaded the pictures, I realized that only one cheek was puffed up. That's odd. Looking closer I saw that instead of being cute and cuddly, it was a decidedly non-cute and non-cuddly fleshy growth of some kind. A tumor? It looks like it has scabs and pus on it. I suppose it could be a botfly, which I know affect squirrels in this region. Bad place for a botfly!

The growth, up close.
 The non-tumor side.

Wednesday, April 20, 2011

Who builds the nest?

First of all, it is amazing that a little bird that hatches out of an egg one June morning, can the next year build a nest of its own that is a typical specimen for its species (with no training even). Secondly, it is interesting that often it is only the female that builds it. The male presumably is above such domestic endeavors.

But not in all species. I'm not positive (and because this is a blog I'm not required to verify it), but I believe that the vireos and possibly other groups engage in dual-sex nest building. (Go check your Birders Handbook and post the answer for me below.) I seem to remember watching two blue-headed vireos both collecting nesting material together once somewhere near a hemlock-lined stream in Pennsylvania. Maybe it was a dream.

Now for the point of my story. Today I witnessed a common thing: a female bluebird making repeated trips to a nest box with a mouthful of nesting materials (grasses, pine needles, etc.). But the interesting thing was that the bright blue male followed her every step of the way, but did none of the work. He would fly with her to a spot several hundred meters away to collect stuff (staying within a few meters). Then he would fly all the way back to the nest while she put it in the box. While she was in there, he would perch on top and sometimes come down to look in.

This has two potential explanations, as far as I can tell: 1) he was guarding her against being cuckolded by rogue males (as she was likely approaching fertility at this point), and 2) well there is no 2. But it is also possible that this "male accompaniment" is some sort of transition between "male doesn't help at all" and "male helps build nest." No proof, but why not. I'm pretty sure there are also cases in which the "male helps a little bit."

Tuesday, April 19, 2011

Miscellaneous dead things

This is a post of random dead things I've come across in the past few weeks...dead things being one of the main things of interest one runs across during winter/early-spring walks! (I know spring is farther along now, but I'm behind.)

This flicker was found inside an abandoned house in Warren County a couple of weeks ago. It looks to be surrounded by dried yew berries. Maybe it wandered in and couldn't get out, and/or maybe it was cached by a squirrel!

These next three were all found in Ocean County this month. Skunks have tiny, delicate feet, which is also reflected in their tiny tracks. This foot belonged to half a skunk I found near a predator burrow (fox? coyote?).

This dead pine snake was brought to my attention by a turkey vulture that was eating it in the middle of a large, wide-open grassland. It didn't smell and was very cryptic, so I was pretty astonished that the vulture had found it. The only visible damage to the snake was a smooshed-in head, so I wonder if the vulture killed it (maybe it had come out of hibernation too early and was sluggish), or if it had died last October when the field was mowed (maybe would have looked more weather-beaten), or maybe just keeled over (do snakes have heart attacks?). This is a threatened species in NJ, and I see a lot of them out in the fields, so mowing during the warmer months would not help in any case. Many of the snakes I find are 6 feet long, so this was a fairly young one, I'm guessing.

Deer skulls are an all-too-common sight in any NJ woodland. But this one has an extra tooth! Looks like a very old deer - the teeth (even the extra one) have lots of wear. Maybe this extra tooth contributed to its demise? I'm not a dentist, but it looks sort of painful. Compare with normal deer skull below.

Tuesday, April 5, 2011

Nestlings by the numbers

After my last post, I started reexamining my pics of Acadian flycatcher chicks to see if I could actually identify the fuzzy tufts that I only recently found out have names. I realized that many of them are actually pretty obvious (see below for key), and I also realized that the close-cropped white fuzz of Acadians make them a pretty good study-species for the aspiring fuzz-identifier (fuzzer?). Compare, for example, the wispy, hard-to-differentiate fuzz of baby grasshopper sparrows. And besides being funny-looking (I especially like the "occipital" patch - #2 - for it's jauntiness), these humble fuzz-patches can even tell an evolutionary tale. If I remember correctly, the Acadian is the only Empidonax to have white rather than tan fuzz, one of several things that make it an outsider in its group (nest structure, range, and habitat also come to mind). Connect the numbered tufts to reveal a hidden picture!

Friday, April 1, 2011

Baby birds are strange

Actual scientific drawing from Saunders (1956)

Very strange indeed. It seems like the random tufts of fuzz on newly hatched chicks are just for decoration. What other purpose could they serve? Warmth? It does look warm, but there's not enough of it. There are apparently names for each little patch, too. I came across a 1956 paper in the journal Bird Banding (by Aretas Saunders) that describes the fuzz from several species, and gives names to each fuzz patch. I don't necessarily see the corresponding patches on the nestling photos that I have (see below), but maybe it varies by species (the drawing is of a chipping sparrow). Maybe I should actually read the article. Here are the patches (refer to numbers on the cute yet scientific drawing above):

1. coronal      } capital
2. occipital     }  tract
3. dorsal
4. humeral
5. femoral
6. caudal
7. secondary   }  alar
8. primary       }  tract
9. crural
10. abdominal  } abdominal
11. lateral        }     tract

Here are some pics of alien nestlings from my files:

 Acadian flycatcher
eastern meadowlark

blue grosbeak

 grasshopper sparrow

field sparrow

Lit cited
Saunders, A. A. 1956. Descriptions of newly-hatched passerine birds. Bird Banding 27:121-128.