When I was in third year, I took a course on wildlife nutrition. It was an extremely dense course, with a lot of random facts about tons of different species. Most of what I learned in that course has since faded away, but a couple of strange things still pop into my head every once in a while. The fact that came to me this morning was: willow ptarmigan chicks require a dietary source of vitamin C to survive. Of course, this came to mind while I was trying to think of a bird to blog about, so here I am writing about willow ptarmigans.
Willow ptarmigans are members of the grouse family, and are widespread in northern habitats. They can be found in Alaska, northern Canada, Europe, Scandinavia, Russia, Mongolia, and in the United Kingdom. The birds in the UK are a subspecies known as the red grouse, and are particularly different from other willow ptarmigans due to the maritime climate found in the UK. Ptarmigans live in subalpine and subarctic habitats, generally staying in areas of thick vegetation. Females may move to slightly warmer regions in the winter months, but males tend to tough out the cold weather.
Willow ptarmigans are fairly unremarkable in appearance. They are chunky birds, with long necks and short legs. In the summer the birds are reddish brown, while in winter they are white with black feathers in their tails. Males and females look fairly similar, though males have two markings above the eyes that become red in the breeding season, and white wings and bellies in the summer. The red grouse in the UK does not undergo a seasonal pelage change like the rest of its species. Instead they stay red throughout the year.
As their name might suggest, willow ptarmigans rely heavily on willow trees to survive. In the winter, as much as 94% of a willow ptarmigan’s diet will come from willow plants. In summer, the diet is much more varied, as the number of plant species available greatly increases. The red grouse subspecies eats mainly heather, which can be up to 95% of its diet.
Most willow ptarmigans are monogamous, though there is a small portion of the population (5-20%) that are more liberal, and take multiple mates. Males court females through a number of behaviours, including tail-fanning, waltzing, rapid-stamping, bowing, and head-wagging. Basically anything that will get the pretty girl ptarmigan’s attention will do. Once the birds have mated, they build a nest in the ground and establish territory. Males are very territorial and protective of both their eggs and nest.
Four to fourteen eggs are laid in June or July. Females are responsible for brooding the eggs, though males help protect her and the nest (this is the only grouse species where males actually help with parenting). After about twenty days the chicks hatch. They are well-developed at birth, and begin feeding on their own the same day they hatch. After a week, they don’t have to rely on their parents for warmth, and they can fly after just ten days. Unlike their parents, ptarmigan chicks consume mostly insects, using the high protein content to fuel their fast growth. Oh yes, and they need lots of vitamin C. Even though they can synthesize vitamin C in their kidneys, this apparently isn’t enough. Most captive birds are just fed on chicken diets, and when this was tried with ptarmigan chicks, the birds developed scurvy and died before four weeks of age. Plants in the chicks’ natural diets contain very high levels of vitamin C, so the chicks can save energy by getting dietary vitamin C instead of synthesizing it themselves.
Before I finish this post, I’d just like to thank all my faithful (and unfaithful) readers. While writing this I reached 25,000 views on this blog, which is very exciting for me. So thanks for visiting, and hopefully I keep entertaining you!
Cover image By Francesco Veronesi from Italy – Willow Ptarmigan – Alaska 040004, CC BY-SA 2.0