One day a few years ago, my friends and I started looking up the names for groups of animals. Everyone knows the generic ones, like a "flock" of birds and a "herd" of cattle, but it turns out that if you dig deeper, there are some pretty awesome group names. Have you heard of a murder of crows, an unkindness of ravens, or a parliament of owls? How about a smack of jellyfish, an exaltation of larks, a romp of otters, or a pitying of turtle doves? If you're like me and you're fascinated by this, you can check out lots more animal group names here and here.
One group of animals in particular has been on our minds lately here at Hawk Ridge: a kettle of Broad-winged Hawks. "Kettle" isn't a group name quite like the others; it doesn't refer to the species of birds involved, but to the form that they take as they fly.
In this post, I explained a little bit about how thermals work, and for the sake of my typing fingers and the sanity of those of you reading this post whose job it is to explain thermals all day, every day, I'm not going to go over it again in detail. Visit the links above for an explanation, which can be as simple as "warm air rises!" or as complicated as specific heat capacity and pressure and inversions and cool stuff like that.
In a nutshell: hawks have a long way to migrate, and they would rather not expend a lot of energy if they can help it. So they soar up on thermals, circling and circling and getting as high as they can before gliding down to the bottom of the next thermal, and the next, and the next, all the way down to South America. Here's a diagram I found on this website that explains the process pretty well.
So what exactly is a "kettle" of hawks? Usually, birds riding thermals don't do it alone. When one bird finds a thermal, others fly in to join it, and pretty soon they make a swirling mass of hawks, called a kettle. It's pretty spectacular to watch, as more and more birds join the kettle and your binocular view fills with dozens or hundreds of birds.
Above is an example of one of these kettles. It's really hard to take a decent picture of one, because they can get so high up. The birds in the picture above might look like specks to you, but most of the time we're lucky if we can get that good a view of them. Sometimes kettles can be so far away that they're barely visible in a spotting scope (with a maximum of around 60x magnification). And sometimes the kettles can be right overhead, so you have to crane your neck back to keep them in view and count the birds.
Counting kettles of hawks is one thing I've been learning how to do in the past few weeks. With a few exceptions, it's not a good idea to try to count the birds in a kettle while they're still circling in the thermal. It's when they start "streaming" off the top of the kettle that they form a nice, countable line. In the flight diagram above, the middle bird is streaming: gliding from the top of one thermal to the bottom of the next. When hundreds of hawks do this at once, it's an incredible sight.
In my first post about Hawk Ridge, I talked about our clickers, which we use to tally the different species of hawks we see. Most of the clickers are mounted on wooden boards, but we have a few loose, handheld clickers, which we use for kettle counting. On a big Broad-wing day, the count platform echoes with clicking as two or three counters at a time tally their kettles.
I keep mentioning Broad-winged Hawks (or "Broad-wings" or "Broadies"). What are they, and what's the deal with Broad-wings and kettles?
This is an adult Broad-winged Hawk. It has a reddish-brown head, black and white tail bands, and mostly whitish wings with a black outline on the trailing edge. (This particular bird is molting a few of its tail feathers and maybe one of the outer feathers on its left wing, which is why it looks a little ratty).
But, as I quickly learned when I got to Hawk Ridge, the vast majority of hawks can't be identified by their color pattern or plumage characteristics. They're simply too far away. Instead, we focus on the bird's overall shape, general light and dark coloration on major regions of its body (for example, even from a distance, the pure white head and tail of an adult Bald Eagle stick out in contrast with its black body), and its flight pattern.
So, let's take a more realistic view of things.
Here's a highly cropped version of that first kettle photo. Aha! Now you can't see the reddish color or whitish underwing or tail bands, can you? Instead, let's look at the shape of these birds. As their name suggests, they have wide wings. They also have a pretty short tail, especially when it's fanned out. Their body is pretty stocky, and overall they have a compact appearance. These body proportions are common to most hawks of the genus Buteo, including Red-tailed Hawks and Rough-legged Hawks.
Broad-wings are the most common hawk in these big kettles, and they are the hawk that most likes to soar on thermals. Often, of the hundreds of birds in a kettle, all but a few will be Broad-wings. But usually a few other raptors join the Broad-wing kettles, so counting the hawks isn't quite as easy as clicking a clicker. Before the raptors start streaming, you have to go through and pick out anything that might be different, like these:
Counting kettles is fun, exciting, and exhausting. It makes us all want neck massages. It has brought me dangerously close to falling off the railing of the count platform several times. It can be immensely frustrating when the birds in a kettle fly higher and higher and just refuse to stream off and be counted. But kettles can also lead to some truly incredible hawk totals. Here's the count board at Hawk Ridge on Saturday afternoon. The left column is the past hour, the next column is the day totals, and the right-hand column has season totals written in blue. By the end of the day on Saturday, the counters had tallied 16,815 Broad-winged Hawks, along with 459 Sharp-shinned Hawks and 276 Bald Eagles.
If you're interested in our season totals, check out the Hawk Ridge page on HawkCount. As of yesterday, our raptor total stands at 50,081. Our 50,000th bird was an adult Peregrine Falcon that appeared out of the fog that was beginning to move in on the ridge. We were all glad it was a bird we could point to, and not a distant milling speck in one of the kettles.
Jump to a Post
Welcome to Hawk Ridge
A Massive Migration
A Happy Birdthday
Photos from the Week
Visiting the Banding Station
A Watched Kettle Never Streams
Food, Part 1
The Big Picture
Last Weeks at the Ridge
Belize, Part 1
How to Look at Birds, A Guide (or: Belize, Part 2)
All Creatures Great and Small
Kids and Language, Again
More Photos from France
Food, Part 2
Building Nests in California
Please Do Not Pet the Woodpecker
Condors and Creatures in Big Sur
A Day at Hastings
I am a high school graduate taking a gap year before college. I’m interested in birds, biology, and the natural world, as well as history, foreign languages, writing, and reading.