Bird of the Month December 2018

Female Northern Harrier looking down at a marsh.

Northern Harrier

Circus hudsonius

Northern harriers are a widespread species, found throughout North America, Mexico, and Central America. They are handsome raptors with fairly wide wings and long narrow tails. The most telling feature though is a white patch at the base of the tail on the dorsal or upper side. Males are gray above and white below and smaller than the brown and white females. The female is also brown-streaked beneath, and both species have black banding on the tail. The trailing edge of the male’s wing is dark.

Behavior and Habitat

Northern harriers, once called marsh hawks, are also easily recognized by their behavior. They hover low over marshes and short grasses with wings in a Vee-shape looking and, like owls, listening for, small rodents. They aren’t related to owls but have owl-like faces that assist in hearing the rodents.

Northern Harriers breed in wide-open habitat and nest on the ground. Both sexes help construct the nest which may be up to 24 inches across where the female will lay 4-5 eggs. The female does most of the incubating with the male bringing in the meals. This can keep him quite busy as he often is caring for a second family at the same time. In good years, males have been documented having up to five families going at the same time.

Despite their former name, during winter Northern Harriers use a range of habitats with low vegetation, including deserts, coastal sand dunes, pasturelands, croplands, dry plains, grasslands, old fields, estuaries, open floodplains, and marshes.

Similar Species

Northern Harriers are fairly unique and are not likely to be mistaken if you can watch them for a time. Note the low hovering and the vee wing position, and especially the white patch on the rear.

Cool Facts

The fact that Northern Harriers use their hearing extensively to locate prey (which includes reptiles, amphibians and small birds besides rodents) is unique among non-owl raptors. The disk-shaped face looks and functions much like an owl’s, with stiff facial feathers helping to direct sound to the ears.

“Juvenile males have pale greenish-yellow eyes, while juvenile females have dark chocolate brown eyes. The eye color of both sexes changes gradually to lemon yellow by the time they reach adulthood.”

Northern Harriers have been on this planet for a long time. The oldest individual ever recorded was a 15+-year-old female, but the species has been around for at least 40,000 years, according to fossils recovered in Mexico.

When and where found at Camas NWR

Watch for Northern Harriers in any open habitat on Camas National Wildlife Refuge. They are there year-round so don’t give up during the winter.

Conservation

“Northern Harriers are fairly common, but their populations are declining. The North American Breeding Bird Survey records a steady decline of over 1% per year from 1966 to 2014, resulting in a cumulative loss of 47%, with Canadian populations declining more than U.S. populations. Partners in Flight estimates the global breeding population at 1.4 million, with 35% spending some part of the year in the U.S., 17% in Canada, and 10% in Mexico. They rate an 11 out of 20 on the Continental Concern Score and are not on the 2014 State of the Birds Report. Habitat loss has contributed to reduced harrier populations as people have drained wetlands, developed land for large-scale agriculture, and allowed old farmland to become reforested. The small mammals that harriers prey upon have been reduced because of overgrazing, pesticides, and reduced shrub cover from crop field expansion. Because they eat small mammals, Northern Harriers are susceptible to the effects of pesticide buildup as well as direct effects by eating poisoned animals. In the mid-twentieth century, their populations declined from contamination by DDT and other organochlorine pesticides but rebounded after DDT restrictions went into effect in the 1970s. Northern Harriers have been mostly safe from hunting because of their reputation for keeping mouse populations in check, but they are still sometimes shot at communal winter roosts in Texas and the southeastern United States.” www.allaboutbirds.org/guide/Northern_Harrier/lifehistory

 

Male Northern Harrier has prey in its talons.

Text by Terry Thomas. Source: https://www.allaboutbirds.org

Photos by Terry Thomas.