A robust and adaptable predator, the red-tailed hawk should be familiar to anyone who looks up on Martha’s Vineyard. The species is present here year-round in significant numbers, and nests widely across the Island. And its high-flying habits make this bird of prey easy to spot: If you’re out and about, it’s a rare day indeed (or a seriously inclement one) when you can’t spot a red-tail or two riding a thermal, wings and tail feathers spread wide.
Yet when I think about my relationship to this species, I realize it’s a bird I don’t actually know very well. To be sure, I’ve encountered it thousands of times in my 27 years on the Vineyard, and can identify it readily out to artillery range. But despite its familiarity, the red-tail often holds its cards surprisingly close to its chest.
First, some things I do know. Adults of the species are readily identified by their unique, uniformly reddish tail, generally obvious on birds in flight, and often visible on perching individuals. Youngsters sport, instead, a brownish, narrowly banded tail. But at all ages, this is a massive, thick-bodied, short-tailed raptor, and those structural features alone are often enough to identify it.
These birds are skilled and versatile predators, with small mammals making up the majority of their diet. But red-tails also have the ability to find and capture reptiles and amphibians, or even smaller birds when an opportunity arises (and they are not at all opposed to taking a chicken from time to time). Red-tails are notably resourceful in their methods, hunting from a perch, soaring in search of prey, or even flushing potential prey items from a low-level cruise, depending on the circumstances.
Although their habit of nesting in large trees (pines are a favorite) is well-known, and although I often have a general sense of where pairs are nesting, I think I’ve only actually seen two or three red-tail nests in my whole time on the Vineyard. These birds can be remarkably stealthy around their nests, and the nests themselves, though bulky, are often well-concealed. Combined with the extreme mobility of these hawks when they are out foraging, their secretive nesting habits make it very hard to estimate how many pairs usually breed here. (My guess is about two dozen.)
The size of our wintering population, at least, appears to have increased quite steadily over recent decades. On Christmas Bird Counts (CBCs) back in the 1960s and 1970s, red-tailed hawks were often found only in single-digit numbers, with a low of five individuals in 1971. Numbers in those days were presumably depressed by the sad legacy of pesticides such as DDT. In rural areas like the Vineyard of the 1950s and 1960s, some hawks were also undoubtedly shot as known or potential poultry stealers, or perhaps just as enticing targets for someone holding a shotgun.
Since those days, however, single-digit CBC counts of this hawk have been rare, and probably associated with beastly weather for the count, which suppresses both observer activity and the activity level of soaring birds such as red-tails. The 1990 CBC, for example, produced only nine red-tails, but numbers were uniformly low on that count, and I’m glad I missed it. The highest CBC red-tail count I’m aware of, 71 in 1995, was exceptional, but over the past 30 years, Vineyard CBCs have typically turned up around 50 red-tails. Numbers in recent years may have shown a dip, though it’s hard to tell if it’s a real downward trend, or just random year-to-year variation.
But early winter numbers, which are what the CBC reflects, are not necessarily indicative of the size of our nesting population. For one thing, the size of a particular year’s cohort of young can have a big effect on CBC results, which don’t generally capture the age classes of birds that are observed. A bumper crop of young inflates the tally, though not all of the immatures boosting the count will survive to breed successfully.
Moreover, seasonal movements may be muddying the waters. I’m curious about whether, how often, and in what numbers our breeding red-tails abandon the Island during the usual autumn migration window for this species. (The species migrates fairly late, with numbers of transients at mainland sites probably peaking sometime in the second half of October.) And are Vineyard winter numbers augmented by migrants arriving from the mainland? I’ve never seen a red-tail leaving or arriving on the Island, and long water crossings are avoided by many soaring birds that depend on thermals for lift. But that doesn’t mean they don’t ever do it.
Familiarity, in this case, may not have bred contempt, but it has certainly encouraged complacency. The red-tailed hawk is common, conspicuous, and frequently encountered on the Vineyard. But those are qualities that often mute the interest of a naturalist. Combined with the ability of this species to be stealthy when conditions warrant, the familiarity of this species has made it a sort of mystery in plain sight.
