Brood Patch

I found a pair of violet-green swallows nesting in a natural cavity of an Oregon ash tree. There were small, dead branches right outside of the entrance that made the perfect perch. As the female landed and began to preen her feathers, I could see that she had developed a brood patch.

For an egg to develop normally and hatch, a certain temperature range must be maintained. One of the ways birds achieve this is by sitting on the eggs and incubating them. To help facilitate the transfer of heat from the parent to the egg, birds temporarily develop a bare patch of skin on their belly called a brood patch. Certain hormones are produced that cause the feathers to fall out in this spot and to create additional blood vessels in the bald area to help transfer warmth to the eggs. Some birds, such as ducks and geese, may pluck their feathers to create a brood patch. The feathers that are shed can also be used to insulate the nest to help with temperature regulation. The time spent incubating eggs varies based on the insulating properties of the nest and the temperature of the environment. The bird can sense the temperature of the eggs through its brood patch and will adjust its time spent incubating the eggs accordingly. Birds will also periodically turn the eggs to warm them evenly and prevent the embryo from sticking to the shell.

Nature is an inexhaustible source of wonder. I hope to see you out there.

Resource
Ehrlich, Paul R., et al. The Birder’s Handbook: A Field Guide to the Natural History of North American Birds Including All Species That Regulary Breed North of Mexico. Simon & Schuster, 1988.

Blue-gray Gnatcatcher

The blue-gray gnatcatcher is a beautiful, little bird. The male is blue-gray above and white below. He has a white eye-ring and a black line that starts above one eye and curls around the forehead to above the other eye. The females are gray above and white below with the same striking eye-ring. They both have dark tails with white outer tail feathers.

This is a fun bird to watch flitting around through the landscape. When it perches, it has a noticeable behavior of cocking its tail, slightly fanning out the feathers, and swaying or wagging it back and forth.

Its nest is an open cup that is woven with small fibers and decorated with bits of lichen or bark. It looks similar to a hummingbird nest. Peterson has the length of the blue-gray gnatcatcher at 4.5 inches and Cornell lists it as 3.9 - 4.3. So they aren’t much bigger than a hummingbird.

The range map on All About Birds by the Cornell Lab doesn’t have them this far north, but lots of birds are expanding their range northward. This bird’s breeding range covers a lot of the United States from coast to coast. There is a small band across the lower part of the country where it can be seen throughout the year. Check out the range map at Cornell.

This bird is small and can be challenging to spot, so it’s helpful to also stay tuned into its vocalizations to find it. I love checking out how Roger Tory Peterson describes its voice in his Field Guide to Birds of Western North America. Here’s what he says: “Call a thin, peevish zpee; often doubled, zpee-zee. Song a thin, squeaky, wheezy series of notes.”

Happy birding! I hope to see you out there.

Western Kingbird Nesting

For reasons I don’t understand, kingbirds have chosen to nest on one of the high voltage towers out at the arboretum. The sound of the electricity crackling across the wires is audible from a fair distance. Never mind that the sound of sizzling is loud up there where they are nesting, being that close to high voltage electricity I imagine is not good for their health and the health of their babies. On top of that, I feel like those metal beams would heat up pretty hot in the noon day, summer sun. Again, I can’t believe that this would be an attractive site for them to nest. Trying to put a positive spin on it, I thought that they certainly won’t have to worry about ground predators like snakes and squirrels. Also the view is probably nice from up there and that will come in handy to detect and chase off predatory birds such as owls, ravens, crows and hawks that are in the area. It also looks fun as they dive off the tower and glide down to the hillside to forage.

They have a light gray head and a white breast that fades into a yellow wash on their bellies. They have a stout bill and a black tail with outer tail feathers.

They are a beautiful bird to observe and they love the open landscape of the east side of Mount Pisgah. I see them perching on top of brush piles and on dead limbs of shrubs like buckbrush. They are mainly insectivores and they will use these perches to forage by hawking insects out of the air or flying down to the ground.

Listen for their vocalizations. Peterson describes their voice as “shrill, bickering calls; a sharp kip or whit-ker-whit; dawn song pit-PEE-tu-whee.” I feel like Peterson always has interesting descriptions of a bird’s songs and calls. Check it out and see what you think.

I hope that you are getting in some birding time this spring. Nature is an inexhaustible source of wonder. I hope to see you out there.

Sources
Peterson, Roger Tory. Peterson Field Guide to Birds of Western North America, Fourth Edition. Houghton Mifflin Harcourt (HMH), 2010.

Western Kingbird Overview, All About Birds, Cornell Lab of Ornithology. https://www.allaboutbirds.org/guide/Western_Kingbird/overview. Accessed 30 May 2025.

Red-breasted Nuthatch Excavating Cavity

In my experience out at the arboretum, red-breasted nuthatches excavate their cavities and white-breasted nuthatches use existing natural cavities or nest boxes. This red-breasted nuthatch is working away on a Douglas-fir snag. I could hear the muffled hammering as it carved away. After a minute or less, it would appear in the entrance to the cavity with a mouthful of shavings. Sometimes it released the shavings from the entrance and sometimes it would pop out onto the side of the tree and let them go. The wood appears to have become very soft as the shavings looked like dust falling through the air. I think the nuthatch was excited about the consistency of the wood. It seemed to be vigorously and merrily chiseling away its new nest and it occasionally gave a toot from the entrance which sounds like a miniature tin horn. The male and female both excavate the nest with the female doing more. That said, the bold markings on this one appear to be the male, and males without mates may begin excavating several cavities at once in an attempt to attract a female. I need to go back and see if this male is in a relationship. After the cavity is constructed, she will line the bottom with soft materials such as fine grasses, strips of bark, fur, or feathers. Interestingly, I read that they will spread sap around the entrance to their nests. I love this little bird! I hope you are getting in some good birding so far this spring.