Hardly a Life of Royalty

by Karen Nichols

The Golden-crowned Kinglet is a very small songbird. Adults are olive-gray on the upperparts with white underparts, with thin bills and short tails. They have white wing bars, a black stripe through the eyes and a yellow crown surrounded by black. Wikipedia

Golden-crowned Kinglets are a mystery and a marvel of wintertime survival in the north woods. These grey and olive birds weigh only the mass of two pennies — just bigger than a Rufous Hummingbird. This species is Montana’s smallest permanent resident passerine and it eats insects all year.

Named for its brilliant gold and fiery orange crown-patch (yellow only on the female), and bordered by black, Regulus satrapa is Greek for “a ruler who wears a gold crown.” This royal name might accurately reflect its appearance, but the Golden-crowned Kinglet’s lifestyle more closely resembles a peasant than a prince.

Scientists cannot fully explain how they can survive brutally cold northern winters. The birds winter throughout the United States, breed in Canada and Alaska, and are year-round residents in the coniferous forests of the Northeast and western states. 

Montana has two kinglet species, the Golden-crowned and Ruby-crowned. However, new DNA studies suggest they are not closely related. The Golden-crowned Kinglet is much more closely related to the Eurasian Goldcrest (Regulus regulus). Experts recently removed the Ruby-crowned Kinglet from the genus Regulus and placed this species in a separate genus, Corthylio. 

While we Montanans cradled our hot cups of cocoa and stoked our fires during the recent December cold snap, the tiny Golden-crowned Kinglets fluffed their downy feathers and shivered through the nights that plummeted to minus 35 degrees. At daybreak, they began non-stop feeding, often hanging upside down from small twigs, using their tiny bills to pluck soft-bodied arthropods.  

In Bernd Heinrich’s Winter World, he describes watching four kinglets feed for over an hour during a cold day. “The birds foraged tirelessly, without pause. I timed them at an average of 45 hop-flights per minute, without any apparent change of pace.”

Heinrich once checked the gizzard of a dead kinglet in winter, finding 39 geometrid (inchworm) caterpillars. 

The bird needs to eat constantly to brave the cold and maintain its high body temperature of about 44 degrees C or 111 degrees F. Its body temperature is about 2 degrees C higher than that of most birds and 6-7 degrees C higher than humans. A resting Golden-crowned Kinglet has a heart rate of about 600-1200 beats per minute depending on its activity (What it’s Like to be a Bird, Sibley).

Scientists say the birds are stretching the limits of physics to not freeze solid when darkness stops their ceaseless feeding. They are not known to roost in cavities at night like chickadees and nuthatches do. When sunset comes, kinglets roost nearby, wherever night finds them.

Researchers speculate that kinglets may dip into nocturnal hypothermia and/or torpor, but have found little direct evidence. Kinglets have been observed huddling together at night in small groups of 2-4 birds on a protected tree branch or beneath a snow-covered brush pile, shivering to maintain their body temperature.   

Golden-crowned kinglets are covered with highly insulating downy feathers that they can fluff out to an inch thick. Heinrich determined kinglets had about four times greater feather mass committed to insulation than to flight. At night, they tuck their heads and feet into the down, which helps to maintain the difference between body and air temperature of up to 78 degrees C. 

If a kinglet goes without food for only a few hours during the day, it will die.  Golden-crowned kinglets suffer an average winter mortality rate of 87 percent.  There are reports of 100 percent mortality during severe winter storms. 

To offset the extreme winter mortality rates, kinglets produce unusually high numbers of eggs. The average clutch size is 8-9 eggs and most pairs produce two broods a year. 

Pairs begin nesting in early spring, the female choosing a nest site in the upper canopy of a mature conifer, often beneath a heavy limb. They collect moss, lichen, spider silk, insect cocoons, downy plant matter, and birch bark strips to build a dense hammock-shaped nest. They line the nest with up to 1 ½ inches of insulation including hare fur and feathers from other birds. Spring snows accumulating on the conifer branch above the nest can provide additional insulation. 

Few nests have been reported in Montana. One sighting near Libby in 1941 was of a pair of adults taking materials to a nest during the third week of March. Fledglings have been reported as late as mid-August in western Montana, likely reflecting multiple nestings (Birds of Montana, Marks, Henricks, Casey).

As the first brood fledges, the female starts building another nest for her next clutch. The male takes over feeding the first brood. 

The female stacks her eggs in two layers, usually five on the bottom and four on top. How does the female kinglet adequately incubate eggs laid in two layers? Kinglets can heat up their legs to a temperature of 39 degrees C to circulate heat all throughout the nest, incubating and shuffling the tiny eggs. Nesting success is over 80 percent. (Heinrich). 

Golden-crowned Kinglets are more often heard than seen, so it is always a special treat to see the breeding males with their fiery orange crest. Listen for their high-pitched tsee -tsee-tsee call notes in the crowns of mature trees. I often cannot distinguish between the calls of a Brown Creeper and a Golden-crowned Kinglet, so I hope for a glimpse of the kinglet’s erratic movements to tell them apart. 

In Montana, Golden-crowned Kinglets depend on mature and old-growth forests of spruce-fir and cedar-grand-fir forests with dense canopy cover for breeding. In winter, they feed in more diverse habitats, including deciduous forests, second growth or slash piles.

While the breeding range has expanded in the Midwest and eastern U.S. due to spruce and other conifer plantings, populations have declined in Montana. In Montana, data indicate declines of 8.2 percent per year between 2000-2010.  (Birds of Montana, Marks, Hendricks and Casey). 

Like Brown creepers, Golden-crowned Kinglets have a high affinity for old-growth forests. Populations on breeding grounds have been negatively affected by logging and clear-cutting (birdsoftheworld.org).

We can assist these kinglets by maintaining extensive stands of mature and old-growth conifers and by valuing and protecting the insects that sustain these amazing birds. And by maintaining our curiosity and enthusiasm for these survivors who may resemble little kings but hardly have a royal life of luxury.