Northern Harrier on Winter Hunting Ground

November 16, 2022 ~ “Winter” along the upper Texas Gulf Coast, typically gets air quotes, because it hardly qualifies. But this day followed a cold snap, and offered gray skies, temps in the mid-40’s, and a stiff breeze that made me glad I was bundled up in 3 shirts and a neck scarf. I spent 6 hours exploring Bay Avenue, and the boat ramp, right along the Intercoastal Waterway [name corrected 27-11-2022] in Freeport, Texas.

Google Maps Street View of Swan Lake Boat Ramp on the Intercoastal Waterway, near the intersection of State Highways 332 and 257, in Freeport Texas. Satellite View inset shows winter marshes and graded marshland near the Swan Lake Boat Ramp.
(Click on any photo once to enlarge in a new window; close that window to return here.)

The Intercoastal Waterway is a navigable canal carved through roughly 1000 miles of sandy marsh from  Carrabelle, Florida, to Brownsville, Texas, along the Gulf Coast. It is separated from the Gulf of Mexico and its hammering waves by a few thousand feet. It crosses numerous wandering streams that coalesce from the marshes and wetlands, taking rainwater to the sea. Where it crosses natural drainage courses or entrained ponds, it creates wonderful habitats for wading birds. The constant ebb and flow of shallow brackish water, not only from tides, but also from the wakes of regularly passing tankers and barges, feeds the shoreline mollusks, fish and crustaceans. The Intercoastal maintenance crews have recently re-graded much of the sand in the area, removing several inland feeding spots, but more are opening. The inexorable forces of water and gravity will have their way. In the above pair of images, you can see the recently graded land, some mowed land to the southwest of the dock, and the regrettably bulldozed land to the east of the dock.

Lindheimer’s Guara, blooming profusely in mid-November, Freeport, Texas
Samsung Galaxy S10e phone photo

One of the fall flowers blooming profusely on the sandy soil was this Lindheimer’s Guara, recently featured in Linda Leinen’s post, The Incredible Lightness of Guara. Spotting it here in the winter landscape of half-dead grass was like seeing a friend. This snapshot was taken looking southwest across the triangular spit of land between Swan Lake and the Intercoastal, past the tussocks and tufts of salt marsh. Flat, flat, flat.

Northern Harrier slowly flapping up over the hillock
1/2500 sec. f/5.6 ISO 2500
Nikon D850 with Nikkor 500mm f/5.6E PF ED VR

Fortunately, I was looking in the right direction as this young raptor appeared silently over a dune about 200 feet away on a low strafing run. The low slow-flap flight path, and ringed neck told me this was a Northern Harrier, Circus hudsonius. The russet coloring of the bird I saw was that of a juvenile; adult males are gray, with black wing tips, and adult females are creamy with light brown streaking. Juvenile male Northern Harriers have pale greenish eyes, while juvenile females have dark chocolate brown eyes; as they mature, both gradually change to the lemon-yellow eyes of the adults. The light was low enough that I was seeing mostly pupil, so the eyes looked very dark. I’m going with juvenile female, though it’s not a positive identification.

Harrier takes a closer look
1/2500 sec. f/5.6 ISO 2500
Nikon D850 with Nikkor 500mm f/5.6E PF ED VR

She headed straight for me and my chittering camera. Perhaps she thought I was an over-large squirrel chattering away at her. More likely, she was worried I was an interloping hunter, determined to steal her juiciest morsels. Those powerful chest muscles were fun to see. Northern Harriers eat small rodents and small birds, which they can supplement if needed with small reptiles and amphibians, and with large insects. They can take larger prey such as rabbits and ducks; I saw one take a Coot at Anahuac NWR three years ago. They don’t have the bone-crushing talons of a larger hawk or eagle; Harriers typically drown large prey.

Juvenile Northern Harrier soars low overhead
1/2500 sec. f/5.6 ISO 2500
Nikon D850 with Nikkor 500mm f/5.6E PF ED VR

Determining I was of little interest, she wheeled out over the canal, then circled back, maintaining a low flight path over the marshland to the south and west, staying below the horizon for all short prey. I watched her as she sketched wide looping circles across the sky, growing smaller with the distance, until she faded out of sight past Swan Lake. The genus name, Circus, is derived from the Ancient Greek, Kirkos for “circle”, describing this bird of prey’s circling flight pattern.

Northern Harrier range map, courtesy of All About Birds

The Northern Harrier is one of 16 different species in the genus Circus. From the species list on Wikipedia, it appears that each continent and major geographic area of the world has just one Harrier species, and the Northern Harrier is ours, here in North America. Interestingly, there is not a “Southern Harrier”; South America has the Long-winged Harrier, Circus buffoni. The Northern Harrier is a “leapfrog” migrator, with the birds migrating from the farthest north flying to the non-breeding winter grounds farthest to the south. Migration is spread out over time: the birds migrate during the day, typically alone, and stop frequently along the route to feed.

Juvenile Northern Harrier showing white rump patch
1/2500 sec. f/5.6 ISO 2500
Nikon D850 with Nikkor 500mm f/5.6E PF ED VR

Often, after the Harrier slipped out of sight, I would look up from work on the other birds at the boat ramp, and there she’d be, silently circling over the marsh. Keeping the camera on her was a challenge. She frequently flew behind wind-blown weeds, and in front of the houses on the beach between the Intercoastal and the Gulf. I managed to get one dorsal shot of her pristine white rump patch, a key identifying mark.

Hoping to pin lunch
1/2500 sec. f/5.6 ISO 2500
Nikon D850 with Nikkor 500mm f/5.6E PF ED VR

Several times, she dove to the ground, feet hanging like grapples, lowering herself between the tangled growth. I was interested to see that her claws were not open as she dropped, probably giving her a more streamlined form for penetrating through the low dense weeds. I didn’t have eyes on her at all times… but I think it is safe to say she rarely, if ever, caught anything during the 6 hours I was working along the boat ramp. Juvenile Northern Harriers have been observed to be successful at taking prey in 27% of their attempts, while adults were successful in 33% of their attempts. By comparison, Red-tailed Hawk juveniles and adults were successful in 54% and 66% of their attempts, respectively.

Juvenile Northern Harrier rests on a low shrub
1/2500 sec. f/5.6 ISO 1600
Nikon D850 with Nikkor 500mm f/5.6E PF ED VR

At one point, she landed in a low scraggly tree, and watched the boat dock area for a while. All these photos posted together, give the impression that she was with me for one extended visit, but that is not the case. I would watch her and take some photos, and eventually she would leave, always returning 30 or 40 minutes later. I drove away from the area for a quick bio break; when I returned an hour later, she was still coursing over the marsh.

Harrier harrying Caracara
1/2500 sec. f/5.6 ISO 1600
Nikon D850 with Nikkor 500mm f/5.6E PF ED VR

A Caracara, probably weighing twenty percent more than she does, thought he had hidden himself in the salt cedar right next to the boat dock channel, probably looking forward to a fish dinner. The Harrier would have none of it. She hovered above and to the left of this photo, then dove and swooped, pulling up right before smashing into the bush. She repeated this … harrying … behavior three times, but the Caracara was undeterred, and she finally gave up and wheeled away.

Northern Harrier resting on ground, far away
1/2500 sec. f/5.6 ISO 2000
Nikon D850 with Nikkor 500mm f/5.6E PF ED VR

At one point, she went completely to ground… and then sat and rested for a bit. She did not appear to have caught any prey, and was not feeding. This photo is for “documentary” purposes… the bird was roughly a quarter-mile away, and smaller than the little red focusing square in my viewfinder; this wide crop will help me remember the knee-high salt-marsh grasses and plants on the sand bar.

Juvenile Northern Harrier angles away
1/2500 sec. f/5.6 ISO 2500
Nikon D850 with Nikkor 500mm f/5.6E PF ED VR

During the winter, Northern Harriers roost in groups typically of 20 birds (though groups of 2 to 85 have been observed) on the ground, hidden among the short thick vegetation, sometimes along with Short-eared Owls. Individuals each have a small patch of open ground; their patches are connected by runways under the grass and thick vegetation. The communal roosting site is located in the middle of an area with plentiful prey. The same roosting site may be used for just a few nights, or may be used for several months; it may be revisited in following years. Many thanks to the USDA for the research paper providing many of these details. Reading that paper made me wonder if that grassy area where I saw the Harrier on the ground could be a communal roost area? Only she knows.

So, winter, characterized as the season of dormancy and hibernation, is anything but along the Gulf Coast. Here, juveniles are defending their territory and building their hunting skills, as the earth travels its circus around the sun.