A Whiter Shade of Pale

Despite the colder temperatures and snow of late across most of Colorado, the birds have definitely been signaling that spring is on its way. In fact, astronomically, the spring equinox happens next month (this year it’s March 20th). When you think of spring, what comes to mind? For some people, me included, one of the most common indicators of spring is the reappearance of the American robin in your backyard.

Partially leucistic or "piebald" American robin in northern Colorado. Photo by Jamie Simo.
Partially leucistic or “piebald” American robin in northern Colorado. Photo by Jamie Simo.

The American robin (Turdus migratorius) is one of the most ubiquitous song birds in North America. While it’s commonly believed that they migrate south in the fall (and some do, particularly those in the upper reaches of Canada and the U.S.), a lot of robins actually spend their winters where they spend their summers. They just might not be as visible because they’re clustered together in trees eating berries instead of on the ground foraging for worms.

A few weeks ago, I noticed that the robins had returned. Spurred on by hormones, their winter flocks were breaking up and they were starting to lay claim to spring breeding grounds. One day, I was watching a couple of robins on the roof of my neighbor’s gazebo when I did a double take; one of the robins had a partially white head! What was going on?

Color in animals is dictated by the amount of pigments in the cells of their skin, hair/fur, scales, or feathers. One of those pigments is called “melanin.” The darker the animal’s features are, the more melanin is being produced. Albinism is the total absence of melanin and results in an all-over white or pale pink coloring (the pink is the blood vessels showing through) and, often, red eyes. Last summer, I visited the Colorado Gators Reptile Park in Mosca, Colorado, and saw several albino alligators, but this robin clearly wasn’t like them; Aside from his head, the robin was a normally colored bird. What else could explain his unusual look?

Albino alligator at the Colorado Gators Reptile Park in Mosca, Colorado. Photo by Jamie Simo.
Albino alligator at the Colorado Gators Reptile Park in Mosca, Colorado. The green is from algae. Photo by Jamie Simo.

Similar to albinism, leucism also involves a reduction in color in the skin, hair/fur, etc. However, scientists believe that leucism differs in that pigments (melanin as well as other pigments) are produced, but not deposited in particular areas. This can result in an animal that’s completely white with normal-colored eyes, one that is a muted shade of its usual coloring, or even one where only patches of the animal are white (called piebald). The latter is probably the category my robin fits into. Piebald is a common color pattern in domestic animals such as horses, dogs, cats, and cows.

Leucism, like albinism, can make an animal more susceptible to predators by reducing its natural camouflage. In addition, because melanin provides structural support to feathers (hence why the wing tips on even white birds are typically black), an albino or leucistic bird where the leucism affects the wings, may experience more feather wear. This, in turn, could cause problems during migration. It’s also been theorized that albinism and leucism could cause problems in animals, such as some birds, that rely on color for mating displays, or that it may cause problems trapping heat in cold climates because paler colors reflect more solar radiation than darker colors.

So far there doesn’t seem to be much of an impact on my leucistic robin neighbor, but the real test will be this upcoming breeding season.

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Spotlight on Parks: Golden Ponds

One of my favorite parks to visit is Golden Ponds in Longmont, CO. Like many other parks along the Front Range, Golden Ponds used to be a gravel mining site until it was donated to the City of Longmont by its previous owner Vernon Golden. It was dedicated as a district park in 1990. Today, it plays host to a number of animals, especially waterfowl such as Canada geese and mallard ducks. In the summer, osprey can be seen fishing in the park’s 4 ponds.

Waterfall at Golden Ponds Park in Longmont, CO. Photo by Jamie Simo.
Waterfall at Golden Ponds Park in Longmont, CO. Photo by Jamie Simo.

Golden Ponds is deceptively small-looking, but actually encompasses 88 acres. The trail that loops around the ponds also takes you past St. Vrain Creek and a beautiful waterfall. Linger there as long as you wish. It’s a favorite area for kids and families alike. Continuing on over a footbridge, you’ll link up with the western end of the St. Vrain Greenway, a scenic trail that runs east to west through the city of Longmont. It’s a fantastic walk on a beautiful day with amazing views of the mountains, including Longs Peak, the highest point in Boulder County.

Beaver at dusk in Golden Ponds Park in Longmont, CO. Photo by Jamie Simo.
Beaver at dusk in Golden Ponds Park in Longmont, CO. Photo by Jamie Simo.

While most mammals are pretty scarce during the day when the park is busy (and it’s definitely a busy park!) this past fall I was lucky to see the resident beaver foraging in the creek a stone’s throw from the trail. Another park visitor told me to keep an eye out for a mink that also makes its home on the creek. Although I’ve never seen one, signs warn visitors to be on the lookout for mountain lions in the area. More commonly seen though are birds, including the aforementioned waterfowl. On a recent trip, I caught sight of two American wigeon dabbling near the bank of one of the ponds. As is usually the case, you’re more likely to see wildlife near dawn or dusk.

Golden Ponds is a great place to fish, cook burgers on provided barbecue grills, or just take a walk. Leashed dogs are welcome in the park as well as on most of the St. Vrain Greenway, and the wide, level paths in the park are handicap accessible. Picnic shelters can be reserved for $35 a day for residents with an additional $9 fee required for non-residents.

Entrance to the park is free and the park is always open, so what are you waiting for? If you’re in the area, come check out Golden Ponds!

Owl Always Love You

With less than a week until Valentine’s day, store shelves are filled with candy, red and pink hearts, and stuffed animals. While we’re perhaps contemplating a romantic, candle-lit dinner to celebrate, most animals are still hunkered down just trying to stay warm. Springtime and courtship rituals are far from their minds. Others, however, have been in a loving mood for some time, including the great-horned owl.

A male great-horned owl keeps an eye on visitors at Twin Lakes Park in Gunbarrel, CO. Photo by Jamie Simo.
A male great-horned owl keeps an eye on visitors at Twin Lakes Park in Gunbarrel, CO. Photo by Jamie Simo.

The great-horned owl (Bubo virginianus) is the most widely dispersed owl in North America. While sources differ over how many exactly, there are a number of subspecies based mainly on regional variations in habitat, color, and size. Part of its success is due to its high adaptability. It may nest in the woods or in urban areas, take over an old squirrel nest in your backyard, or set up shop in a sign over an office building. It is also one of the earliest birds to breed in North America.

Way back in November and December while we were preparing for the winter holidays, the great-horned owl was already courting. Courtship for great-horned owls involves hooting back and forth, bowing, and bill rubbing. While the great-horned owl is monogamous, they spend most of the year within the same territory but apart from their mate except during the breeding season.

A female great-horned owl incubating her chicks at Twin Lakes Park in Gunbarrel, CO. Photo by Jamie Simo.
A female great-horned owl incubating her chicks at Twin Lakes Park in Gunbarrel, CO. Photo by Jamie Simo.

Depending on the area, with southern owls laying their eggs earlier and northern owls laying later, the female owl will lay between 1 and 5 white eggs in January or February. For approximately the next month, she will incubate them while being fed by her partner. Cornell Lab of Ornithology currently has a great-horned owl nest camera set up showing a female incubating her eggs in Savannah, Georgia.

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In some species, both male and female birds will incubate their eggs, but only female great-horned owls do this. This is helped by something called a “brood patch,” an area of the belly where feathers fall out to expose a swollen area of flesh like a hot water bottle. The incubating bird presses the brood patch directly against the eggs (and resulting chicks) to keep them warm while in the nest.

A great-horned owlet peers out from its nest at Twin Lakes Park in Gunbarrel, CO. Photo by Jamie Simo
A great-horned owlet peers out from its nest at Twin Lakes Park in Gunbarrel, CO. Photo by Jamie Simo

Like most other birds, once the owlets hatch, they are tiny, naked, and helpless. The term for this is “altricial.” But over the next 6 to 8 weeks, they’ll grow down, followed by feathers. Once this happens, they’ll be ready to “fledge,” or leave the nest. Fledging doesn’t mean fleeing the coop, however. Juvenile owls will stay close to their parents for months, leaving to find their own territories in the fall either of their own accord, or after their parents have gently persuaded them!

One of the best places to see nesting great-horned owls in northern Colorado is at Twin Lakes Park in Gunbarrel, CO. Easily seen from the trail, the owls consistently return to the same hollow tree to raise their young. If you’re in the area this Valentine’s day, it’s a romantic (and free!) activity to do with your sweetheart.

From Groundhogs to Prairie Dogs

Happy Groundhog Day!  Today is the day when we eagerly (some more than others) await whether the groundhog in Punxsutawney, PA, will see his shadow or not. The superstition goes that if “Phil” does, there will be 6 more weeks of winter. Apparently Phil did see his shadow this year, so spring is still a little ways off. But what the heck is a groundhog anyway? If you live in the western U.S., including Colorado, and/or you’ve never seen the Bill Murray movie Groundhog Day, you may have never seen one. And what makes a groundhog different from that more ubiquitous western rodent the prairie dog?

As I’ve already given away, both groundhogs and prairie dogs are rodents, which means that, like mice, they have continually growing front teeth that they must constantly wear down by gnawing. They also share the same family: Sciuridae. This group of rodents includes squirrels and chipmunks.

A groundhog hides in the grass in Dulles, VA, trying not to be noticed. Photo by Jamie Simo.
A groundhog hides in the grass in Dulles, VA, trying not to be noticed. Photo by Jamie Simo.

The names “groundhog” or, its other common name, “woodchuck,” are pretty vague, but the animal’s taxonomic name may give a better clue as to what sort of animal we’re looking at: Marmota monax. The groundhog is a type of marmot, very similar in fact to the yellow-bellied marmot that makes its home at high elevations in places like Rocky Mountain National Park. Unlike the yellow-bellied marmot though, the groundhog is a flat-lander. Back in Virginia, I often saw them foraging in the summer on the grassy side of the road.

Like the prairie dog, three species (Cynomys gunnisoni, Cynomys leucurus, and Cynomys ludovicianus) of which make their home in Colorado, groundhogs are diurnal (active during the day) and live in burrows, but the groundhog lives either alone or with a small group of family members rather than in the large towns that prairie dogs inhabit. They’re also bigger (up to 26 inches long and 9 lbs) than their relatively svelte cousins (up to 16 inches long and 3 lbs) and are more omnivorous, eating more insects along with seeds and grasses.

A prairie dog keeps an eye on passersby at Coyote Ridge Open Space in Fort Collins, CO. Photo by Jamie Simo.
A prairie dog keeps an eye on passersby at Coyote Ridge Open Space in Fort Collins, CO. Photo by Jamie Simo.

One of the biggest differences between the groundhog and the prairie dog, however, is that the prairie dog is considered a keystone species. A keystone is the stone in an arch that, when pulled out, causes the rest of the stones to fall. Therefore, a keystone species is one that, when removed from an ecosystem, causes that ecosystem to collapse. By virtue of their incredible tunneling skills, prairie dogs provide homes for animals as diverse as burrowing owls, rattlesnakes, and cottontail rabbits. Their abundance, and the fact that they don’t hibernate during the winter like groundhogs do, means that they provide a stable, year-long food source for many other animals as well, such as coyotes, hawks, and the endangered black-footed ferret. Recent studies have also shown that prairie dogs help prevent erosion, decrease soil compaction, and encourage the growth of grasses and forbs that large grazers such as bison and pronghorn tend to prefer.

Sadly, the chief skill groundhogs and prairie dogs have in common–digging–is also what puts them at odds with people. There are numerous pest control companies tasked with removing groundhogs from people’s lawns. Even worse has been the wide-scale eradication campaign against the prairie dog since the early twentieth century due to fears that prairie dogs compete with livestock for forage or that stepping in prairie dog burrows causes injuries to livestock.

Given their benefit to the prairie community, perhaps the prairie dog needs to take a page from their cousin the groundhog and come up with a better PR campaign. Maybe starting with an official Prairie Dog Day?