Bunking in and living in boxes: here’s no place like home

By BILL CHAISSON
Of a Feather
I’ve got a starling nesting in my eaves, which is pretty annoying. It has found a crevice that leads to a space behind the indifferently hung vinyl siding that went up over the clapboard some years ago and apparently leads to an egress into the balloon structure of the house. As I sit here writing this I can hear them rustling around inside the wall. By now they have built their nest and have perhaps even laid their first clutch of eggs. Starling eggs are blue with a hint of green, a bit like a robin’s, but a couple of shades lighter.

The European starling is an invasive species and has presumably lived in proximity to built structures for as long as there have been built structures in Europe. The so-called rock dove, better known as the pigeon, has similarly accommodated itself to built structures. Both the starling and pigeon nest on cliffs and other rock faces when there are no buildings around.

This habit of adopting man-made structures is, of course, not confined to Old World species. The phoebe, which is a member of the tyrant flycatcher family, a group confined to the New World, has readily adapted to living on the horizontal members of out-buildings and barns and occasionally on porches attached to houses. Robins will do this too, but they are brassier than phoebes and don’t seem bothered by human traffic. I’m not sure the phoebes that nested on my mother’s porch last spring successfully raised a brood.

Barn swallows are even named for the structure they nest in. I’d be interested to hear of this species nesting in some non-structure location. The taxon, Hirundo rustica, breeds nearly through North America, but is also the same species that is found in the Old World, where it is called the common swallow and breeds across all of Europe and Asia. Before the advent of abundant anthropogenic structures, this species also nested on cliff faces.

Many raptors have also made this transition. When I worked in midtown Manhattan I frequently saw several species of hawks streaking by my 14th story window. The old-fashioned masonry buildings and skyscrapers (e.g. the Empire State Building) were often built “stepped back” from the street, the floors getting smaller in area toward the top. These steps and the various wider ledges added as decoration were (and are) perfect nesting spots for falcons, accipiters, and buteos. 

The re-introduction of the peregrine falcon to the East Coast was carried out after 1976 largely in urban settings because research by the Peregrine Fund of Cornell University found that strategy to be the most successful. Falcons reared in captivity have been released in urban areas across the country over the last 40 years. The species was removed from the federal endangered species lists in 1999.

Of course, there are even more bird species that are happy to take up residence in houses that you build for them as opposed to co-habiting with us in the structures we build for ourselves. The most famous example is probably the bluebird, which declined through the 20th century due not only to pesticides in its food chain, but also to more scientific methods of pruning orchards and then the transition away from standard size trees entirely. 

Bluebirds, alone among the thrushes, are cavity nesters and through the 17th to 19th centuries had adapted well to living and breeding in orchards. Apples and pears trees were once riddled with dead limbs that broke off to leave hollows in the trees. They were ideal bluebird nesting sites. More aggressive pruning and maintenance practices reduced the number of sites and, when pollution further reduced bluebird numbers, it became popular to build nest boxes for them to help their recovery.

Much research went into pinning down not only the best dimensions for the boxes, but also their height above the ground (4-6 feet), the distance between boxes (300 feet), and the direction they should face (about 15 degrees either side of dead east). Countless Cub Scouts and 4Hers over the last three decades have learned both carpentry skills and a little natural history by building a bluebird nest box.

There are over 60 cavity nesting species in North America and several of them can be convinced to nest in a man-made box. These include the kestrel, the flicker, the wood duck, the house wren, and the purple martin. The last species is perhaps the most intriguing because it is colonial.

The tradition in the Old World is to refer to squarer-tailed members of the family as martins and ones with more forked tails as swallows. We haven’t preserved this distinction in the New World, so square-tailed species like Petrochelidon pyrrhonota are called the cliff swallow, and we have only one species called a martin. Cinerea cinerea is called the sand martin in the Old World and the bank swallow in the New World. (Bank swallows aren’t confined to nesting in river banks. I remember a colony in the pile of sawdust outside a mill in Bristol, N.H.)

In any case, building a martin house is like constructing an apartment complex or group of condominiums. They and are either suspended separately from wires or mounted in a single structure on a pole and generally include 8-12 “rooms.”

Nestwatch.org is an excellent source of details for those who wish to build and erect a martin house. There are many different styles, from separately hung gourds to elaborate faux Arts & Crafts buildings that look like tiny summer resort hotels overlooking a lake in 1900. Martins are particular. They want no buildings or trees within 60 feet of their nest and there should be no shrubs underneath the box. 

The boxes should be 10 to 15 feet above the ground and accessible to the owner, so they can be cleaned, but should have baffles on the pole or even be mounted in standing water to keep predators away.

It is a bit late to put out a nest box this year. Most birds begin nesting in April, but many species raise a second brood and the nest boxes users often won’t raise a second clutch in the same box unless it is cleaned out. These birds may be looking for a clean box, so it can’t hurt to put something out now.