Category Archives: Nature Notes

Last Month in Birding: July 2015

Posted on August 18, 2015 by Rosemary

In July, Massachusetts birders enjoyed another month of unusual sightings. Here are five of the most exciting of these observations as suggested by our experts.

Bridled tern (Onychoprion anaethetus)

A bird of tropical and subtropical oceans, the bridled tern is similar in size to our common tern, but is stouter and has striking black and white facial markings. Outside of the breeding period it spends most of its time over the open ocean, hovering over the surface and dipping its beak into the water to snag fish and other small sea creatures. A bridled tern was sighted in Nantucket in July.

Bridled tern © Lee H. Dunn

Bridled tern in Nantucket © Lee H. Dunn

Ruff (Philomachus pugnax)

A ruff observed on Plum Island last month was a long way from home: the species is native to parts of Europe, Asia, and Africa, breeding in the north and overwintering in the south. Though female and non-breeding male ruffs have an unremarkable appearance, during the breeding season the males display large feathery “ruffs” and battle vigorously for dominance on special display areas called leks. The species’ scientific name means “pugnacious lover of battle”.

Ruff © Steve Arena

Ruff at Plum Island © Steve Arena

White-winged dove (Zenaida asiatica)

This species looks somewhat like a mourning dove, but it has a chunkier body and a tail that is square rather than pointed. Though primarily a species of southern deserts, it is equally comfortable in suburban areas and frequently wanders quite far. Through the years its range has been gradually expanding northward; it often takes advantage of backyard feeders. One bird was briefly observed in Newburyport.

White-winged dove in Florida (CC BY-NC-ND 2.0) Kenneth Cole Schneider

White-winged dove in Florida (CC BY-NC-ND 2.0) Kenneth Cole Schneider

Fea’s petrel (Pterodroma feae)

This relatively rare seabird was named for Italian artist and zoologist Leonardo Fea, and its name is pronounced FAY-ah. It is a member of the tubenose order of birds (Procellariformes), and like other members of this group has the ability to excrete excess salt through tubes on its bill from special salt glands located above of its eyes. This petrel breeds on just a few islands in the Eastern Atlantic. When not nesting, it spends all of its time at sea. One bird was spotted over Stellwagen Bank National Marine Sanctuary—only the second record ever in Massachusetts and one of very few for North America!

Fea's Petrel © Steve Arena

Fea’s Petrel off Truro © Steve Arena

Sandwich tern (Thalasseus sandvicensis)

It’s easy to remember what a sandwich tern looks like: its beak has a yellow tip, which gives it the appearance of having been dipped in mustard. Juveniles may lack the yellow marking—perhaps they haven’t yet developed a taste for Dijon? The species is native to the southeastern US and the coasts of Central and South America. However, one wandered north to Nauset Marsh in Eastham this past month.

Sandwich Tern in Mexico (CC BY-NC-ND 2.0) Sergey Yeliseev

Sandwich Tern in Mexico (CC BY-NC-ND 2.0) Sergey Yeliseev

Mobs Rule

Posted on August 5, 2015 by Rosemary

Have you ever seen small birds dive-bombing a larger one—often a bird of prey? This behavior is called “mobbing,” and it’s a common phenomenon that you may encounter any time you’re outdoors.

Blue jay mobbing red-tailed hawk © Phil Doyle

Blue jay mobbing red-tailed hawk © Phil Doyle

The Mobsters

Mobbing occurs when birds of one or more species aggressively approach a bird perceived as a threat, either perching near it or swooping at it while making loud “alarm” calls. The most vigilant and noisy mobbers include mockingbirds, tyrant flycatchers, wrens, crows, jays, blackbirds, tits, and colonial seabirds such as terns—but other species will mob, too.

The targets of all that fuss are often avian predators such as owls or hawks, but may include nest robbers such as crows, jays, and grackles, or the brown-headed cowbird, which lays its eggs in the nests of other birds. Mobbing species will also swoop at raccoons, cats, snakes, and other non-avian threats. They will even pursue harmless birds such as the insect-eating common nighthawk or the great blue heron, presumably as a case of mistaken identity!

Why Mob?

Oriole mobbing turkey vulture © Patrick Waggett

Oriole mobbing turkey vulture © Patrick Waggett

To a casual observer, mobbing can seem very risky. Smaller birds may get very close to their targets, perhaps even pecking them. Why do birds engage in this behavior? Scientists are not entirely certain. The most likely explanation: members of the avian community are alerting the neighbors that a known miscreant is on the scene. Since predatory birds typically rely on stealth to make a successful attack run, a raptor surrounded by flock of angrily squawking birds loses its element of surprise.

Anyone watching a beleaguered hawk or owl enduring this treatment may wonder why it doesn’t just snatch one of its attackers for a quick snack. But because of their speed and agility, the mobbers almost always have the advantage against a perched raptor. Since the predator has lost whatever advantage it may have had from camouflage or stealth, swiping at its attackers may simply not be worth the energy.

Follow That Mob

Experienced birders use the mobbing phenomenon to locate and attract birds that would otherwise go unobserved. Keep an ear and an eye out for birds of different species making a fuss: they may guide you to a special sighting of a perched owl or hawk.