Blue-gray Silk Snatcher

Its nest is composed of the frailest materials, and is light and small in proportion to the size of the bird.

~John James Audubon on the nest of what he called the Blue-grey Fly-catcher

A friend and co-worker of Melissa says the wispy call of the Blue-gray Gnatcatcher  (Polioptila caerulea) sounds like a faint “Steve”. So, a couple of weeks ago, when I heard Melissa call out, “Steve”, while scanning the treetops, I knew the little dynamos had returned. Their faint song is pretty much out of my hearing range these days, so it wasn’t until a few days later that I spotted my first one, flitting around some tree branches, waving its seemingly too long of a tail back and forth as it snapped up insects too tiny for me to see through my binoculars. Then, last week, we spotted two together at a small Eastern Tent Caterpillar nest on a cherry tree off our deck. The gnatcatchers were pulling silk from the caterpillar nest for use in their own. In the past two weeks we have also seen Tufted Titmice and Carolina Chickadees at these caterpillar structures, although I only saw the chickadee pull out a couple of the larvae and then drop them (they may be too hairy for their tastes). Gnatcatchers make a beautiful nest similar in construction to that of a Ruby-throated Hummingbird, but larger. I wrote about watching a nesting pair at the North Carolina Botanical Garden in an earlier post. Here is a photograph of that nest showing the cup-like structure made of lichens, lined with plant fibers, and held together with spider and insect silk.

Blue-gray gnatcatcher in nest 2

Blue-gray Gnatcatcher in nest from an earlier post (click photos to enlarge)

A couple of days ago, Melissa was working on a museum project out on our porch and told me she noticed that the gnatcatchers had been making regular visits to the caterpillar webbing closest to our deck. I grabbed the camera, my 300mm lens, and a tripod, and took up a position on the deck steps. I spent the next two hours waiting and watching. A few times I was rewarded with a frantic minute or so of trying to capture the quick movements of their behavior as they gathered silk.

Bg gnatcatchers at tent caterpillar nest

The tent caterpillar nest with both gnatcatchers collecting silk – the female at the main web, the male puling from the silk trails left on the branches by the foraging larvae

There were four silk-snatching visits during the time I sat there, mostly by the female. On two occasions, the male accompanied her and gathered some silk from nearby branches while she pulled from the main web structure.

BG gnatcatcher at tent caterpillar nest

Gnatcatcher snapping up strands of silk

BG gnatcatcher with silk in beak

This look reminded me of how I feel with a mouthful of gooey campfire-roasted marshmallows

BG gnatcatcher at tent caterpillar nest 2

She pulled at the webbing from different vantage points on different visits

BG gnatcatcher at tent caterpillar nest 3

She usually snapped at the silk rather than picking at it with just the tip of her bill

BG gnatcatcher at tent caterpillar nest 1

Then she would pull until the silk broke free

BG gnatcatcher at tent caterpillar nest 4

After several pulls, she would fly off with the “glue” that holds her delicate nest together

The birds flew off in the same direction each time, so we will be looking for their nest in the coming days. But, I’m afraid the ones we have found here in the past (up to 75 feet up in the treetops) have not been as cooperative for viewing as the one at the garden.

They Are Catching More Than Just Gnats

may my heart always be open to little birds who are the secrets of living

~ee cummings

Here is a long overdue update on those little birds that nested just outside the garden driveway gate at the Botanical Garden…I am happy to report these diligent parents were apparently successful in rearing their young. You may remember my earlier post where a pair of blue-gray gnatcatchers were building the nest (they finished it around April 10). A few days after that post, I saw the female incubating the eggs, so I tried to keep an eye on her to see when they might start feeding the young. Finally, I saw her off the nest the first week of May. I wasn’t able to get out to photograph them until May 7. That was probably about 6 or 7 days after they hatched. I had trouble counting the tiny heads even after looking at my images from that first feeding day, but I could tell there were at least three young. Later, I saw the fourth beak pressing skyward on one of the feeding bouts, so the total was four.

BG gnatcatchers both adults at nest

Both parents arriving at nest together (click photos to enlarge)

The feeding bouts were fast and furious, with adults staying just a couple of seconds on each trip. What amazed me on that first day was the large number of huge craneflies that the parent birds were bringing in.

cranefly brought to nest

A large adult cranefly is jammed down an open mouth of one of the nestlings

close up of cranefly going to nestling

That a lot of wings and legs to swallow for such a tiny bird

BG Gnatcatcher at nest

Nestlings sometimes had to wait a bit before they could get anything else down

It seemed like about half of the food items brought on that first evening were craneflies. There is a nearby creek and large vernal pool that may be the source of so many of these huge flies (their larvae are aquatic), but I was impressed how many the adult birds were able to catch. Even more impressive was how many the tiny nestlings were able to swallow. On many occasions, a parent brought another food item, but I could still see the long legs of the previous meal sticking out of the beak of one of the recently fed young.

BG gntcatcher with fecal sac

Female removing a fecal sac from a nestling

Of course, what comes in, must go out, so after every few feeding trips one of the young birds would raise its rear end after the adult had passed on a prey item, and the adult dutifully plucked the pre-packaged fecal sac and flew off. Data shows they usually drop it after flying 30 to 40 feet away from the nest (this helps keep the nest area clean of smelly poop that might attract predators).

nestling begging

Nestlings are getting more feathers on their head by May 11 (compare to earlier photo)

I spent some time photographing the feeding of young on three separate occasions, all after the Garden closed at 5 p.m. By the third date, May 11, the young were noticeably larger, more active in the nest between feeding bouts, and getting more feathered, especially on the head. Their huge gape and bright yellow mouth linings were hard to miss, and surely provide a great target for tired parent birds bringing in the food.

feeding the group

Hungry mouths begging for food

I was amazed that, after that first day of a menu heavy on craneflies, the last day I watched them, the adults brought in nary a one. Most of the food items were much smaller, and were difficult to identify even after zooming in on the images.

Adult brining a small moth

Bringing in what looks like a small moth

But the pace of feeding had quickened. That last day, May 11, I decided to keep track of the feedings. I stood out there for a total of 86 minutes that evening. During that time, the adult birds made a total of 51 feeding trips. The longest interval between feedings was 6 minutes. On several occasions, there were 2 or 3 feedings within the span of a minute!

feeding from above

The last day, a new feeding perch was used…the hang-down-from-the-branch-above technique

Although I was hoping for another day of shooting the nest, I thought they might fledge before I returned, as I was taking a long weekend. Sure enough, when I returned to work on May 16, the nest was empty. Records show the young usually leave the nest 10-15 days after hatching, so that puts these guys right on schedule. Here’s hoping they all made it and are out there learning to be on their own.

Catching Gnats and Plucking Lichens

More than with most species of small birds, the attention and interest of the observer center about the nesting habits of the blue-gray gnatcatcher because of the great beauty of its nest.

~Francis Marion Weston, 1949

One of my favorite spring arrivals is the plucky little blue-gray gnatcatcher. It is tiny, but bold. It looks a bit like a tiny mockingbird, but builds a nest like a large hummingbird. My friend, Mary, found a nest at the Garden recently and emailed me where to look as I prepared for a program. I never did find that one (they are often very well camouflaged on a branch). But, a week later, as I was leaving work, I heard the familiar “Steeve” call, looked up, and saw one fly into a small tree. I got out my binoculars, and was pleased to see a nest in progress.

Blue-gray gnatcatcher nest empty

Blue-gray gnatcatcher nest (click photos to enlarge)

A few evenings later, I brought my camera and spent some time watching this industrious duo go about the business of finishing what is certainly one of nature’s most beautiful nests. By this time, it looked like the nest was nearing completion, but the gathering of materials, and fine-tune adjustments, continued for over an hour as I watched.

Blue-gray gnatcatcher with spider silk on bill

Female bringing in spider silk

The nest is a deep (about 3 inches) cup about 1.5-2 times the size of a ruby-throated hummingbird nest. Otherwise, they look almost identical – a somewhat high-walled, elastic nest covered on the outside with lichens and held together with spider silk. The inside is lined with soft materials like plant down, hair, and fine feathers.

Blue-gray gnatcatcher in nest 2

Male checking the feel of the nest

As I watched, both adults were busy contributing to the efforts. During the breeding season, the male blue-gray gnatcatcher (photo above) can be distinguished from the female (photo below) by the presence of their black forehead and supercilium (a stripe that runs from the base of the birds beak and above its eye). The female’s head is plain gray.

Blue-gray gnatcatcher in nest 3

Female inspecting the progress

I had my big telephoto plus a teleconverter, so I was well away from the nest. The birds chose a very busy location for their activity, right next to a road and walkway that is popular with Garden visitors, so I don’t think they minded me watching them.

Blue-gray gnatcatcher in nest 5

Male placing a lichen

There were times when nothing happened at the nest for 10 minutes or so, then there were bursts of activity with a bird bringing in materials (especially pieces of foliose lichens – they look like lichen cornflakes) every minute or so. The usual routine was to fly into  a branch next to the nest, pause, then hop into the nest and place whatever material was brought in. Then there was often some fine-tuning, placing the lichen just so, inspecting it for a second, and then off again. Time spent in the nest on any one visit was usually less than 20 seconds. References say it takes about a week to complete a nest, but I think this pair could do it much faster based on what I saw.

Blue-gray gnatcatcher singing

Male singing

Blue-gray gnatcatcher preening

Male preening

In between nest-building activities, the pair would pause for some singing, preening, or the important duty of nest protection. I am a bit worried about this particular nest, since it seems in a more open location than many I have seen. There are a lot of hazards to any nesting bird, especially one so tiny. I witnessed a few bouts of territorial defense as this pair chased after a crow and a pair of blue jays that flew through their air space. And a pair of brown-headed cowbirds received a lot of attention when they perched within 50 feet of the nest. Both adults repeatedly dive-bombed the cowbirds, who seemed uninterested. They eventually flew off, and nest building resumed about 5 minutes later.

Blue-gray gnatcatcher pressing down in nest 1

Shaping the cup

The final stage of nest building is refining the shape of the cup. This is something they put their whole body into…the adult plops down into the nest with just their head and long tail (the tail accounts for about 45% of the total body length) visible and pushes against the sides of the nest, shaping it as they rotate their body around, flexing the sides until it is just right.

Blue-gray gnatcatcher pressing down in nest

Putting your whole body into getting the shape just right

At times, I could barely see their head at all, with just the slender bill projecting above the lichen wall. I checked on the nest the next few days and saw no activity, so I figured they had completed construction. And now, I see the female sitting in the nest for long periods of time, so I assume she is incubating her eggs. I will keep you posted on their progress.

Garden Birds – Blue-gray Gnatcatcher

I once knew a [beginner} bird-watcher who, not aware that altricial species attain full body size before leaving the nest, spoke seriously of the gnatcatcher as a tiny mockingbird.

~Francis Marion Weston

Indeed, I often describe these active birds as looking and behaving like a tiny mockingbird. They are always fun to watch as they hop through the branches, or hover beneath one, snatching an insect meal. And their small size, white eye ring, blue-gray coloration, and exaggerated tail, make them easy to identify.

Blue-gray Gnatcatcher showiung their distinctive, and active, long tail (click photos to enlarge)

Blue-gray Gnatcatcher showing that distinctive, and active, long tail (click photos to enlarge)

They seem to be in constant motion, especially that noticeably long tail.  In the writings on this bird in Bent’s Life Histories, Francis Marion Weston describes it like this…Certainly the most expressive feature of the gnatcatcher: as of its larger counterpart, the mockingbird: is its long, ever-active tail; now up and down, now from side to side, it is never for an instant at rest.

This is a fairly common species throughout much of North Carolina in spring and summer, with occasional winter stragglers in this area. You usually have a better chance of seeing a few in winter in the Coastal Plain. But most migrate to Mexico or Central America for the colder months before returning in March and April.

A pair has been active for a week or more in the garden area, gathering nesting material, including fine grasses and some dog hair I placed in a hanging basket on a tree branch for use by local nesters Their nests are beautiful examples of avian architecture, resembling a larger version of the delicate lichen and spider silk construction of the Ruby-throated Hummingbird.

Blue-gray Gnatcatcher singing

Male singing. Note the dark forehead and line over the eye.

And I agree with Weston’s assessment of the field marks used to separate the sexes on this diminutive songster… The distinguishing mark of the male gnatcatcher in breeding plumage: the black forehead and line over the eye : is useful as a field mark only at very short distances. Luckily, this guy perched along the fence for a couple of minutes so I could study him in detail as he sang his heart out. I’ll be on the lookout for their comings and goings in the garden the next couple of weeks, hoping to spot their beautiful nest somewhere in my woods.

Note – the last two mornings have added a few new birds to the species list posted on Monday for the garden area:

Black Vulture, Red-tailed Hawk (both seen flying over the power line)

Ovenbird, Northern Parula Warbler, Great Crested Flycatcher (heard in adjacent woods)

White-crowned Sparrow, Blue Grosbeak, Blue-gray Gnatcatcher, Prairie Warbler seen in the garden area