Kinglets: Feathered Balls of Energy!

Ian Stewart

If you see a tiny green hyperactive bird flitting around your yard at this time of year you are probably looking at a kinglet. There are two species of kinglet in North America, and both can be found throughout Delaware during the fall and winter. Their common name translates as ‘little king’ and derives from the bright crown patch found in both species. Kinglets can be tricky to identify because they move so fast, but it helps that they seem oblivious to humans and can be approached closely, and they both often feed quite low. They key to telling the two species apart is to get a good look at their head.

Ruby-crowned (L) and Golden-crowned (R) Kinglets handled for banding

The Golden-crowned Kinglet (Regulus satrapa) is pale gray below with a black and white striped head and a bright yellow crown, which is permanently displayed if the bird stays still long enough for you to see this. Both sexes have the yellow crown, though the males’ crown also contains a streak of flaming orange.

Golden-crowned Kinglet up close

The Ruby-crowned Kinglet (Corthylio calendula) is dull yellow below with a gray-green head and a broad white ring around the eye. Both sexes have this and it is a great field mark, leading to some birders calling this species ‘ringlets’! However, only the male has the ruby crown and it is usually hidden from view, except when they flare it during aggressive social interactions.

Ruby-crowned Kinglet up close

Both kinglets feed on insects and spiders which they glean from leaves and buds, although their different feeding styles can sometimes help you distinguish between the two species. Ruby-crowns often hover as they feed while Golden-crowns often hang upside down from the ends of twigs. Some other identification clues are that Ruby-crowns are usually thought of as birds of deciduous woodland whereas Golden-crowns are birds of evergreens like pines and cedars. Also, Golden-crowns are thought to feed in flocks more often than Ruby-crowns. Speaking personally, I regularly see both species in deciduous woods as well as evergreens, and I have also encountered single Golden-crowns as well as small flocks of Ruby-crowns, so these clues are guidelines rather than rules. Knowing their calls is a good way to identify them. Ruby-crowns announce their presence with a harsh and surprisingly loud chattering ‘ta-chit’ (usually the first call on this list from All About Birds), while Golden-crowns have a high-pitched ‘tsee-tsee-tsee’ call (usually the first call on this list from All About Birds).

Typical views of Golden-crowned and Ruby-crowned Kinglets feeding

Interestingly, although our two kinglets are both in the same family they are not closely related and are placed in a different genus, with the Golden-crowned being more similar to the Old World kinglets. Relatively little is known about kinglet breeding biology because they build well-hidden nests high in trees far to our north, primarily in the boreal forest of Canada. We do know that females can lay up to 12 eggs, a remarkable number for such miniscule birds.

The Delaware Nature Society’s bird banding project has now been running for 5 years in northern Delaware and southeastern Pennsylvania, and during this time we have banded many more Ruby-crowns than Goldens (121 versus just 7), and almost all of them in the fall. Our data suggest that kinglets are moving through in waves during the fall, since we have only recaptured 3 of these 121 Ruby-crowns and all were recaptured within just a few days of banding.

Our banding data shows how tiny these birds are. Golden-crowned Kinglets weigh just 6g, the same weight as a quarter dollar, whereas Ruby-crowns are slightly heavier at 6.4g. Handling kinglets for banding allows you to see the extensive bright red crown of male Ruby-crowns. What is also noticeable is the fringe of forward pointing bristles around their bill, which probably help funnel airborne small insects into their mouth. 

The head of a male Ruby-crowned Kinglet seen from above

I once read that the soles of Golden-crowned Kinglets’ feet are more deeply grooved than those of Ruby-crowned Kinglets. This apparently helps them perch in pine trees more easily because the needles slide neatly into the grooves. However, I have handled both species and their soles look equally grooved to me, though I did notice that Golden-crowns have black feet and Ruby-crowns have yellow feet.

Both kinglets are most common during spring and fall migration, but a significant number of hardy individuals remain here all winter. In late December and early January, teams of birdwatchers spread out across Delaware to count birds as part of the Audubon Christmas Bird Count, a citizen science project that has been running continuously since 1900. Both kinglets are found on every Christmas Bird Count, even when the average December temperature is below freezing, which is quite incredible for a bird weighing just 6-7 grams! (Ruby-crowned average = 45, range 4–150; Golden-crowned average = 179, range 21-470, using data from the last 50 years).

Kinglets can be attracted to your yard using suet cakes (available from Wild Birds Unlimited), and by planting insect-rich native trees and grasses, especially goldenrod. Creating these habitats will benefit many other species of wildlife year-round, and may persuade these little bundles of energy to stay in your yard all winter!

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