Earth Matters: Little Nymphs: Tiny, Fascinating and Unkempt

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Moving across New England in a wave each fall is a small predator that could be one of the most commonly overlooked birds in Massachusetts.

Measuring 8 inches long and weighing less than two tennis balls, little owls breed in southern Canada and the northern United States, and at high elevations such as the Appalachians. They have large gnome-like heads, large eyes, soft feathers, and a tendency to sit obedient when a person is near.

They’re nocturnal, inconspicuous, and – if you’re lucky enough to see one up close – incredibly cute.

The appeal of sharpeners goes far beyond their alluring appearance. Perhaps the most fascinating is an owl that migrates. And their migratory behavior can bode well for their survival in the face of climate change.

When we think of birds that migrate, we probably imagine the colorful songbirds that arrive every spring, such as orioles and thrushes. We could also think of the broad-winged hawks and other birds of prey soaring on the thermals above the ridges of the mountains. Few of us, however, imagine a multitude of little owls flying at night each year between Canada and the southernmost states of the United States.

We are not alone. 19th-century bird watchers considered saw pricks to be year-round residents of the northern United States. Then, in 1906, the owls were discovered among migrating songbirds that had perished in a fall storm on Lake Huron. Today we recognize that a substantial number of little owls move south each fall.

Local banding efforts, including a recent pilot by the Kestrel Land Trust at their new home on the Mount Holyoke Range, have shown that some goads roam our area.

Their migratory behavior creates an opportunity to study the little saw. Bird banding – a state and federal regulated activity of briefly capturing and equipping birds with unique numbered identification bracelets on their legs – is a wildlife tagging technique well suited to the study of birds that migrate in predictable ways. By settling in consistent places and times each year, researchers amass data that helps reveal the distributions, movements, relative numbers and annual production of species. All of this information is used to help conserve and manage cash.

An example of sharing this data came in 2013, when a young female owl we banded in Belchertown was found by another bird bander in Virginia. In 25 days, this little traveler had traveled over 500 miles, recording an average speed of 20 miles per day.

Early saw banding efforts yielded little data until 1986, when banders in Wisconsin attempted to broadcast the male’s publicity appeal, a relentless “toot” that could be the source of the name of the owl (historically it sounds like sharpening a saw with a whetstone).

The technique worked and tens of thousands of little owls have been banded since, creating a large dataset at the US Geological Survey’s Bird Banding Laboratory that allows us to examine large-scale owl movement patterns.

What have we learned? If we think of migratory behavior on a continuum, little owls fall somewhere in the middle.

At one end are our familiar Neotropical songbirds, whose movements between tropical winter homes and temperate breeding sites are tied to historically reliable food resources such as insect outbreaks. While recent studies suggest that climate change is starting to disrupt their established patterns, these birds have a long history of consistent migratory behavior: predictable timing, regular routes, and a tendency to return to the same breeding sites each year. They are also “complete” migrants insofar as the entire population (all ages and sexes) moves each year.

At the other end of the continuum are the great northern owls such as the snowy owl and the great gray owl. Rather than appearing in Massachusetts in a predictable fashion, these charismatic owls perform occasional non-breeding movements (“bursts”) outside their normal range, often in response to collapsing prey populations in which they. specialize.

Eruptions can be viewed as a type of broad and flexible migratory behavior in which birds respond to local conditions. Movement schedules and routes are irregular and birds may not be faithful to breeding sites. Similar behaviors are exhibited by “nomadic” birds that follow unpredictable food resources across the landscape, such as seed-eating crossbills.

Little owls resemble Neotropical songbirds in that they migrate in predictable ways each year. However, much of their behavior tends towards the flexible end of the continuum. They do not appear to have coherent migratory routes, and they may be “partial” rather than “complete” migrants, with adult females and young birds following food resources south and males staying further north.

They also exhibit nomadic behaviors such as reproduction in different locations and movement in response to food resources.

And yet, unlike food specialists like snowy owls and crossbills, little owls feed on a variety of prey: small mammals, insects, and even birds. A large menu means that they are unlikely to see their food source collapse or disappear.

Overall, little owls may be among migrants’ “flexibility champions”. Their adaptability gives me hope for this species, as changes in temperature and precipitation patterns disrupt the delicate synchronizations between migratory birds and the resources they need to survive.

In the face of climate change, birds that have developed flexible behaviors may be better equipped to cope with the dynamic and unpredictable conditions that will characterize life on Earth for the foreseeable future.

The little owl is a tiny creature that most people don’t even know exists, and yet this deceptively adorable ball of fluff could turn out to be one of our most stubborn survivors.

Chris Volonte is Director of Stewardship at Kestrel Land Trust, based in Amherst. She and local master banderer Anthony Hill have banded pups and kestrels in our area since 2012. The concept of a migration continuum is adapted from a 2006 article by Ian Newton, “Advances in the Study of Irruptive Migration ”(www.tinyurl .com / earthmatters-58). To see another column on saw pricks, visit hitchcockcenter.org/earth-matters/a-thing-that-went-bump-in-the-night.

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