Birdwatching at the Morrison Natural History Museum!

Last Monday, a snow storm hit Colorado....in the middle of May.  Although it snowed even as much as sixteen inches in some places, it melted pretty quickly afterwards, leaving an excellent opportunity for many birds that rely on insects for their meals.  After a rain, you can often see birds like the American robin or flicker foraging around (click HERE to read more), using the soft ground to their advantage to try and catch insects that were washed up out of the ground.  After the snow, it seems like a number of birds were attempting to do the same thing.  As I was closing up, I looked out behind the Morrison Natural History Museum, and noticed a bonanza of birds!  I ran downstairs and grabbed my camera, and tried to get some good shots.  Here, we have a male western bluebird (Sialia mexicana), perching on one of the blocks of sandstone from the historic Quarry 5 in Morrison.  This block contains dinosaur bone, making it ironic that the bluebird, a dinosaurian descendant itself, perched upon the block.

There were plenty of American robin (Turdus migratorius) running around, and got a few shots of them!

As we talked about in a PREVIOUS POST, winter causes many birds, including the American robin, to decrease their territoriality, and flock together.

There were several lark bunting (Calamospiza melanocorys) hopping around.  The lark bunting is actually the state bird of Colorado!

A European starling (Sturnus vulgaris) probes the ground.

There were several more male and female western bluebirds flitting around, and I got some pictures of them that I really like!  Below is a female perched on the fence next to the Jurassic Garden!

A male perched on a fence.  Notice the sexual dimorphism displayed here; the male displays much more vibrant plumage than does the female.

A female perched near my car!

Sometimes, I am really, really bad at identifying birds.  Below are two pictures of birds that I think I have identified correctly, but am not positive.  The first I think is a picture of a pair of chipping sparrows (Spizella passerina).

This one gave me a bit more trouble.  I think this bird is either a western wood-pewee (Contopus sordidulus) or a least flycatcher (Empidonax minimus).

Finally, a yellow-rumped warbler (Dendroica coronata)!

Works Cited:

Robbins, C. S., Bruun, B., & Zim, H. S. (1983). Birds of North America. New York: Golden Press.

Stokes, D. W., & Stokes, L. Q. (2010). The Stokes field guide to the birds of North America. New York: Little, Brown.

Flickers on a Rainy Day

Rain makes lots of animals behave differently than they normally do. Many birds either take shelter or, like the American robin, head out to forage for drowning worms. The other day (and by other day, I mean several months ago, because I kept forgetting to post this post) during a rainstorm, I was walking with my friend Mona when we noticed a flicker stabbing repeatedly at the ground.

Here is a picture of the end result of what we were witnessing!

According to one source, the Puget Sound Backyard Birds, ants compose about 80% of a flickers diet, and foraging for this tasty insect snack is probably what the flicker was doing as it continually stabbed its beak into the ground! Even if it wasn't looking for ants, most of the flickers diet is insects. During the winter, when insects can become scarce, the flicker consumes berries and seeds. Certainly an unusual diet and foraging behavior for a woodpecker!

Below is a video uploaded by Deepa Mohan of a flicker foraging for food.  As you can see in the video, this flicker is foraging when the weather outside is not so frightful.  I assume that perhaps the flicker we saw was active while it was raining both because the insects would be scurrying around trying to find safe ground, and also probably because the ground was softer than usual.  

Like other woodpeckers, the flicker will nest in holes of trees, but will sometimes nest in the abandoned burrows of birds such as the belted kingfisher or the bank swallow, whose nests are located in holes within the earth.  Below is a picture of a pair of belted kingfishers flying into their nest:

Flickers are pretty common where I live, and they seem to be pretty common throughout the United States!  If you have any great flicker stories or pictures, make sure to send them in or comment below!

Works Cited:

Flocks of Robins and Winter Territoriality

Where I live in Colorado, and in fact across much of North America, the American robin (Turdus migratorius) is a common sight, especially during the spring and summer.  You can often find this bird hopping across the ground, rooting around in the ground for worms.  However, this morning, on my walk across campus, I noticed a flock of about thirty or so robins in a random tree, and couldn't remember a time when I had seen so many robins in one place, not even close.  What was going on?

Just like for a robin, a little digging proved fruitful....or should I say wormful?  "The Great Backyard Bird Count" (GBBC) revealed that during the winter, the territoriality of the American robin decreases dramatically.  Two graphs on the website, which I have included below, help us to understand what is going on.  The first graph, titled "Percent Submissions With Positive Sightings," charts the number of people who see robins.  As you can see, the peak months for robin sightings are between the months of April and July, with a peak in July.  March, as well as August through October, are also pretty good times to see robins, but during the winter months between November and February, robins are not seen as often.

The second graph, titled "Average Number of Birds for Positive Sightings" charts how many robins people typically see together: i.e., if they report a robin sighting, they also report how many robins there were together.  As you can see, April through September are definitely the worst months to see multiple robins together, with October through February being the best time, and a large peak in November.

Graphs are tough: what does this all mean in English?  Essentially, during the breeding season (spring and summer), robins maintain strict territories, which causes them to spread out, with a more even distribution.  This means that you would be more likely to see a robin on a walk through the park, but not several robins in the same place.  During the winter, presumably because their breeding territories are simply too small for them to get enough food, and since it is no longer the breeding season, they abandon their territories, allowing different robins to go wherever they wish.  For whatever reason, probably something to do with mutual protection, they also form flocks.  The forming of flocks also causes the number of individuals per sighting to increase.

Another study conducted by the GBBC (read the full write-up HERE) pertained to snow depth and frequency of robin sightings.  As you can see in the graph below, the likelihood of spotting an American robin with even just a little bit of snow drops quite dramatically.  Similar results were reported for the red-winged blackbird, while birds such as the white-throated sparrow and northern flicker responded to increased snow depth as well, but not quite as dramatically.

For the robin, a bird that typically feeds on the ground, even just a little bit of snow cover might prove to be an issue.  However, other ground-feeding birds, such as the dark-eyed junco, didn't seem to mind the snow anywhere near as much as the robin.  GBBC suggested that other factors must affect the distribution of these birds, such as "weather, diet, and the species' normal range and altitudinal limits."

A subspecies of the dark-eyed junco called the gray-headed junco.  I took this picture of the stuffed animal when we were in Ouray over the summer.

A picture of a dark-eyed junco that I took in my backyard.

The GBBC devotes a paragraph to acknowledge the uncertainties in these results, a humility that I find refreshing and, sadly, not too common on many Internet sources these days.  GBBC looks at the graph below, plotting the snow depth against the likelihood of seeing a house finch, and notes the steady decline, as opposed to the sharp drop seen in the robin graph, or the lack of real pattern seen in the junco graph.  GBBC reports that this would be a pattern not expected if it was access to the ground (or lack thereof) that was causing these birds to move.  Instead, one would expect the sharp decline of the robin graph.  Other factors, such as temperature, could be what is causing birds like the house finch or the house sparrow to move.

A male house sparrow.

A female house finch, silhouetted against the backdrop of the evening sky.

Works Cited:

"Snow Depth Survey." The Great Backyard Bird Count. http://www.birdsource.org/gbbcX/science-stories/past-stories/snow-depth-survey (accessed January 23, 2014).

Stokes, Donald, and Lillian Stokes. The Stokes Field Guide to the Birds of North America. New York: Little, Brown and Company, 2010. (accessed January 23, 2014).

"Winter Robins." The Great Backyard Bird Count. http://www.birdsource.org/gbbcX/science-stories/past-stories/is-that-winter-flock-of-robins-in-your-yard-unusual/ (accessed January 23, 2014).