birds – Eyes on the Wild

Uber Eats is for the Birds

The past few weeks have been prime time for nesting birds and their young. No matter what the adults eat, the diet of a baby bird is pretty much entirely arthropods – insects, moths, caterpillars, spiders, and the like – foods that are high in protein, perfect for growing bones and muscles.

If a bird catches an insect for its own consumption, it usually eats it right away. So if it is carrying the insect around, the odds are high that it is on its way to feed its babies. A Common Yellowthroat male, with an unidentifiable insect:

A female Red-breasted Nuthatch, deep in the woods, has caught a Cranefly. (The adults eat conifer seeds in winter, but arboreal arthropods in the breeding season). Only the male actually has a red breast!

A Chickadee with a juicy caterpillar:

To see birds feeding the babies directly, you have to know where the nest is. The easiest way is to have a nesting box. These two Northern House Wrens came and went all day long with insects for the unseen young in the interior.

As they got bigger, they stuck their heads out in an importunate plea for food:

A sizable insect:

placed right in the baby’s mouth:

Occasionally, the two parents failed to coordinate, and arrived simultaneously, creating a traffic jam:

A polite dance ensued. ‘You first.’

‘I’ll wait’:

‘No, yours is bigger’:

‘All right, here I come’:

Eventually, the young will fledge, leaving the nest but staying nearby and still dependent on the adults for food.

Tufted Titmouse adults eat 2/3 insects, and 1/3 seeds and mast, but they feed their young with insects, including bees. This one is feeding its fledgling, about 30 feet up in the trees.

It has a bee or wasp of some kind:

which the baby struggles to swallow unassisted:

The next generation is well provided for.

No place like home

I spent the last three weeks in England, and my first day back in Maine is always special. I settle down into this magical place with a sigh of delight and comfort. Here’s what I saw and heard that first June day: nothing dramatic, but the fabric of my world.

A chipmunk, grooming, not bothered by me so, long as I stayed in my chair and sipped my wine:

Sheep Laurel, Kalmia angustifolia, in flower by the beaver pond:

A minute scarlet jelly fungus, Tulasnella aurantiaca, on a rotting log:

Two garter snakes on my garden wall, a favorite place when the granite has been warmed by a day of sun. Only one was willing to pose:

with sleek bronzed scales:

As evening fell, there were fireflies by the small vernal pool in the field, impossible to photograph, but like having fairies in the garden. The flashes are made by this Say’s Firefly, Pyractomena angulata.

After dark an Eastern Whip-poor-will, Antrostomus vociferus, called from right outside my window. A sort of nightjar, their scientific name reflects the fact that they are very, very loud, but I was delighted to hear it because they have become quite rare, classified as Near Threatened.

It is in the same place every evening, and one dusk it started up while it was still light, so I went out to try and see it. It flew up, and away, and I was sorry I had disturbed it, but it was back the next night. They nest on the ground, and I have looked, to no avail.

And then, at about 4am, a fox barked, sharp and rasping, very close to the house.

A wild and savage sound to welcome me home.

PS In London, foxes wander round Brompton Cemetery in broad daylight:

But here in Maine they are usually wary and I have never heard one bark by the house before.

PPS Google AI produced this excellent summary of how the firefly’s light flash is made:

“Fireflies produce their signature glow through a chemical process called bioluminescence, which operates in a specialized organ called a lantern in their abdomen. This reaction is highly efficient, converting nearly 100% of its chemical energy into light without producing heat. [1, 2, 3]

The mechanism involves four key components mixing in the insect’s light cells (photocytes): [1, 2]

Luciferin: A light-emitting compound.
Luciferase: An enzyme that acts as a catalyst to speed up the reaction.
ATP (Adenosine Triphosphate): The fuel for cellular work.
Oxygen: The trigger for the glow. [1, 2, 3, 4]

When the firefly takes in oxygen, the luciferase enzyme facilitates the binding of luciferin and ATP. This oxidation process creates an unstable, high-energy molecule. As this molecule quickly drops back to a lower energy state, it releases the excess energy as a visible flash of light. [1, 2]”

Sibling rivalry, and a singing heron

[My final Costa Rica blog post, I think.! Then back to Maine.]

On the Pacific side of Costa Rica, we saw two juvenile White Ibises (or if you prefer, ibes (Latin), ibides (Greek)!), Eudocimus albus. They were hunting for crustaceans in the shallows of a small river:

Their eyes focus on the tip of their beak, but they mostly forage by touch. The left-hand one found something:

and a tussle ensued:

The original finder hung on, and brought up a crayfish:

Drifting around the canals on the Caribbean side, in Tortugero National Park, there was a diverse heron population. My favorite was the Boat-Billed Heron, Cochlearius cochlearius. It has large eyes, and is mainly nocturnal:

It gets its name from the keeled bill:

The unusual bill is used as a scoop: the bill is lowered partly underwater and the bird walks forward, thrusting it in front. No other heron species does this.

We saw many Little Blue Herons, Egretta caerulea. As juveniles, they’re purest white:

poking around on a fallen tree amongst the bromeliad plants:

but more skittish that the Boat-billed Herons:

As they get older, their virginal white becomes splotchy:

until it is entirely displaced by the adult purplish slaty blue grey:

The Bare-throated Tiger Heron, Tigrisoma mexicanum, hung around the dock. This is not a wall-painting, but a real live heron:

From time to time it lifted its head, and gave forth its call:

They sing especially at dusk or dawn, and in the breeding season: listen to this video, which I’ve placed on YouTube in the hope that works (let me know if it doesn’t): https://youtu.be/pwoeHLOaHwM

Perhaps the most technicolor bird was this denizen of the littoral vegetation, the Purple Gallinule, Porphyrio martinica:

Like its drabber cousin, the Gray-cowled Wood Rail, Aramides cajaneus, it walks on floating vegetation and overhanging bushes:

PS Costa Rica’s location means it often serves as the southernmost part of the range for North American Species, like the White Ibis, and the northernmost part of the range for South American species, like the Gray-cowled Wood Rail. But yet other species are limited to Mexico and Central America, like the Bare-throated Tiger heron.

The Dangerous Phase

As summer reaches its peak, the nesting season is more or less over, but like teenagers the baby birds are not yet independent. They have mostly left their nests, and sit on branches cheeping urgently for food deliveries. Soon they will have to fend for themselves, and then migrate. Mortality is high in this interlude betwixt the parental home and true adulthood.

These are some I have seen in the last few weeks. In my big hickory tree, two Hairy Woodpecker chicks hopped around:

The House Wren fledglings are still being fed, three days after leaving the nest, and several trees away:

A White-breasted Nuthatch seemed to have only a single chick:

A chickadee had ended up on the ground, but it clambered back up to a low branch shortly after I took the photo.

Black-capped Chickadee fledgling on ground by beaver pond.

The next shot is a food delivery by a Common Yellowthroat mother, right:

Common Yellowthroat fledgling, left, and mother, right

She then pokes it down the fledgling’s throat:

A hummingbird posing on my garden trellis:

The scaly head feathers are distinctive for juveniles. At this age, you can’t reliably tell if it is male or female; the male’s ruby throat only develops later. However, male fledglings usually have streaks on the throat. so the pure white throat of this bird suggests it is female…

On the water, the ducklings are becoming more independent too. This Wood Duck duckling was nowhere near any adults, with just one sibling.