There’ll Be Bluebirds Over

The American composer of “There’ll be Bluebirds over the White Cliffs of Dover” either had the excuse of poetic license or didn’t know that bluebirds are absent from the British Isles. But the song became one of one of Dame Vera Lynn’s signature performances for stirring patriotic hope in 1942.

There are three species of bluebird in North America (all thrushes). Someone who grew up in Tidewater Virginia doesn’t remember seeing Eastern bluebirds here in the 1960s, probably because urban sprawl and competition from introduced species robbed them of natural cavities to make home. But no longer.

nestboxes
Male Eastern bluebird (photo: Inge Curtis)

The friendly songsters are now common in local meadows and suburban gardens thanks to human interference, sponsored by the Virginia Bluebird Society and kindly people who provide nestboxes. The best boxes are not the kind found in knickknack stores, gaily painted (for predators to find) and with a perch close to the entrance hole (to help predators look inside). Constructed of rot resistant cedar, an ideal box has a 1.5” entrance hole protected by a wire mesh predator guard and a snake guard on the pole. While these safeguards are not 100% effective, most broods reach the fledgling stage for the most dangerous days of their lives.

Bluebirds are nesting in two of our four boxes, each with five sky blue eggs. I don’t peep inside again until the chicks have flown after gorging on countless insects and arachnids brought by doting parents. Then, I clean out old nests that might harbor parasites, and usually find the lodgers have made new ones of pine straw and small sticks a few days later for a second brood. Even if I trained for months using forceps to weave the straw I doubt I could craft anything that would pass a bird’s inspection.

Our third box is still vacant and the fourth has a house wren sitting on brown speckled eggs.

Bird eggs are among the most beautiful objects in nature. They are delicate works of art, sometimes decorated with pigments as if squirted from paint guns in the oviduct on the day before laying. It is no surprise that ground-nesters have camouflaged eggs or that eggs laid further north tend to be darker to absorb more heat. We might expect cavity nesters, such as owls, kingfishers, woodpeckers, and wood ducks, would have pure white or buff eggs as coloring provides no obvious advantage. The colors of bluebird and wren eggs are among the exceptions, which goes to prove that nature hates uniformity and ruins our simple hypotheses.

Box taken over by house wrens
Adopted by house wrens

Data from over 4,500 nestboxes on 410 trails across Virginia are compiled by the Bluebird Society. Our local chapter of Master Naturalists monitors a few hundred boxes in parks and around golf courses every week between March and July. On a trail where I help to monitor 41 nestboxes, there were 63 bluebird fledglings in 2018  (a wet spring) and 97 last year, plus a few broods of chickadees and tufted titmice. Nestboxes raise thousands of extra birds.

This year the coronavirus pandemic disrupted our survey, but not the breeding season, which may even benefit from less human traffic and noise. But human nature doesn’t seem to change as I heard that three of our boxes have been vandalized. Who could do that to bluebirds?

 

Virginia Nature Journal for April

Algernon Swinburne

Smells arouse old memories, good and bad. The coconut bouquet of prickly gorse bushes evokes memories of ranks of jasmine blossom on the chalky downs of the Isle of Wight where I was born and Algy Swinburne grew up. Oh, to be in England, now that April’s there (Robert Browning). But here in Tidewater Virginia, the scent of pine resin at this season conveys no particular emotion for me, nor can it trigger flashbacks.

Crabapple tree blooming in April
Crabapple tree blooming in April

I read that memory is less aroused by sound than by smell which owes its potency to a handshake between our olfactory bulbs and the hippocampus. But when I hear the lazy phrases of a blackbird, my mind is transported to a remembered English garden where one sang every afternoon announcing its territory from a perch in apple blossom. But here, where brown thrashers, wood thrushes and mocking birds are better musicians, the chorus of woodland songsters never evokes the same emotion, perhaps because some neural networks close after childhood.

And yet less emotion does not mean less care for the birds that choose to make a home in our yard. In a landscape where native plants of Virginia are retreating before the advance of so many inedible aliens, they need us when food supplies reach a nadir. The bird feeder was not full for very long and never empty during the winter. Long before our neighborhood birds started looking for nesting sites I made a batch of boxes for them, one for every acre. They are luxury condos made of durable white cedar with green shingle roofs and a critter-guard against snakes, raccoons and squirrels.

WelcomeEggs_smallThe boxes were designed for bluebirds, which are surely in the top ten for popularity. Cavity nesters depend on these artificial homes because cautious park officers and yard owners fell dead trees which might have offered them a home. Apart from untold numbers of nest-boxes in gardens, there are 230 boxes around public trails and golf courses in James City and York counties that are monitored weekly by local naturalists. It is exciting to find a clutch of 4 or 5 bluebird eggs (sky blue, of course), and experts assure us that a brief inspection does not affect breeding success.

The program has reversed the steady decline in their population, and now there are more bluebirds in the area than at any time in living memory. Over 700 of them fledged from these boxes alone last year. The Virginia Bluebird Society collects breeding data from across the state, and at summer’s end we will know what impact the hard winter had on their population.

Chickadee nesting in bluebird box
Chickadee nesting in bluebird box

There were bluebirds in our yard until the deep freeze started in February, but we saw few afterwards. There are reports of birds found dead in nest-boxes where they were roosting. Drinking water was frozen for several weeks, and there were few berries or other natural foods at the end of winter. Perhaps the hard weather explains why a chickadee took up residence in one of our bluebird boxes, a tufted titmouse in another, and Carolina wren is building a nest in a third. One box is vacant where a pair of bluebirds raised two broods last year.

Bluebird laying recordBluebirds are nesting elsewhere, but they started late this year, although no later than in the past two years. Our records for 2012-15 suggest their breeding schedule is flexible, so that hungry fledglings are not hatched before insects are abundant again. In the warm spring of 2012, the first eggs were laid three weeks early.

The great horned owls breeding on Jamestown Island don’t have to be respecters of temperature and weather because their prey is ever present. They were sitting on eggs in January, and their owlets were almost ready to fly when the bluebirds were starting to gather straw and down to line their nests.

Red-shouldered hawk on nest
Red-shouldered hawk on nest

Besides the vagaries of weather, bluebirds face the daily challenge of evading predators. They have little to fear from nocturnal species like owls, but a pair of red-shouldered hawks has taken up residence in our woodlot, and I guess they have chicks sitting on the untidy matt of sticks in the fork of a loblolly pine. Their breeding schedule coincides with the re-appearance of frogs and reptiles and when baby rodents set foot out of the nest and naïve baby birds flutter out of theirs. We hear the hawks screaming kee-rah all day long to scare birds out of cover or before taking a dive at them on the bird feeder. I feel no special sympathy for an English sparrow in yellow talons, but there would be a rush of emotion if I noticed a splash of blue on prey feathers.

Next Post: Cuisine for Carnivores