Sligo Creek Dictionary

We’re learning new words every day as we explore Sligo Creek and other Anacostia River tributaries. We thought you might want to learn right along with us. You will find links to stories where the words are used in context, and you can find links in the stories that take you here. We hope this proves to be a great resource for everyone, especially teachers and students.

Assortatative mating — wildlife, especially birds, choosing mates of a similar size

Auricular feathers — specialized, soft feathers that cover the ear openings of birds. 

Anthropomorphize — give human characteristics to animals and other inanimate objects.

Brood — a family of young animals produced by a bird.

Carrion — the decaying flesh of dead animals. Turkey vultures, for example, don’t often kill prey themselves but they do eat already dead ones.

Clutch — a group of eggs produced by birds, like the Canada geese we’re documenting.

Ethology — the scientific and objective study of animal behavior, usually with a focus on behavior under natural conditions, and viewing behavior as an evolutionarily adaptive trait.

Epaulet patches – patches of black on a bird’s shoulders resembling ornamental shoulder pieces worn on a military uniform.

Gabion wall

Gabion wall — a retaining wall made of stacked stone-filled cages tied together with wire. Find a big one at the University Boulevard stormwater retention ponds behind the Kemp Mill shopping center.

Gully at retention ponds

Gully – what you and I might call a ditch, a gully is a landform created by running water and eroding soil. A long gully winds through the start of Sligo Creek near the Nicholas Drive pedestrian bridge to the retention ponds. A gully shouldn’t be confused with a gorge, which is a much grander valley between mountains or hills, with a stream running through it. Also not to be confused with a ravine, which is a deep, narrow gorge with steep sides. The Sligo Creek gully fills with water after hard rains.

Invasive Japanese Barberry

Invasive species – a non-native plant spread by natural processes and by human activity that overtakes native plants and damages the natural ecosystem. Their proliferation can prove fatal to wildlife such as deer as their stomachs are not conditioned to eat it – and it kills the native plants they need to eat to survive.

Immature vs. Juvenile bird — the term juvenile bird refers to a bird in its first plumage, while the term immature bird refers to all non-adult birds. A juvenile bird is immature, but only immature birds in their first plumage would be called juvenile.

Natural selection — the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution. See nifty animated video.

Plumes, Occipital – Occipital plumes on a great blue heron are the long feathers extending from the backs of their skulls.

Plumes, Scapular – Scapular plumes are the feathers of a bird that cover the tops of their wings when they’re at rest.

Canda geese preening

Preening – bird maintenance behavior in which birds use their bills to position feathers, interlock feathers, clean plumage, and remove parasites

Primeval – a feeling or action that is based on primitive instinct

Retention Pond (Stormwater Retention Pond) —  an artificial pond with vegetation around the perimeter, and includes a permanent pool of water in its design, such as the University Boulevard retention pond in Wheaton (the pond is often a pair of ponds when there’s less rain, and one big pond after rain or snowmelt). It is used to manage stormwater runoff to prevent flooding and downstream erosion, and improve water quality in an adjacent riverstreamlake or bay. Learn more about Montgomery County Stormwater Retention Ponds throughout our site and at the Montgomery County Department of Environmental Protection.

Snag — a dead but still-standing tree, like the ones by the University stormwater retention ponds. Birds like kingfishers and green herons, among others, love to perch on them to survey the area looking for food.

Sord — the name for a group of mallards on the ground. A group of mallards in the air is called a flock. Note there is no “w” in the word “sord”.

Stropping motion – blade sharpening-type motion often used by birds including great blue herons when they nudge each other.

Thicket – a dense group of bushes or trees.

Watershed — an area of land that contains common bodies of water such as creeks and streams that all flow into a larger body of water. The Sligo Creek Watershed is part of the Anacostia River Watershed, which becomes the Potomac River Watershed. They all ultimately end up in the Chesapeake Bay Watershed and the Atlantic Ocean.