Tag Archives: Endangered Species

The Black-Crowned Night Heron

 The Black-Crowned Night Heron Hamilton

July 27 2011

Early Morning just arrived at fishway

Scientific name: Nycticorax nycticoras  
Family:
 Ardeidae
Order: Ciconiformes  
Class:
 Aves

PHYSICAL CHARACTERISTICS:

Black crowned heron

The Black-crowned Night Heron (Aukuu in Hawaiian) is an attractive bird to watch. They look like dark silhouettes as they fly with steady beats of their broad wings.

In Flight

As nocturnal feeders, night herons are not be seen often by people. This heron has a stocky, chunky body with short, strong legs and neck, and large red eyes. The body of the black-crowned night heron looks as if it is hunched over, or squat shaped with its head usually tucked down into its shoulder. When in flight, the heron tucks its neck in close to the body and rarely extends it. They have a short thick sharp pointed black bill. The body of an adult Heron is 58 72 cm (20 28 inches) long.

Young black-crowned night herons are brown and streaked with white. The eye of the juvenile black-crowned night heron is yellowish or amber and their legs are a dull gray.

juvenile heron

The sexes are alike except the females are on average slightly smaller. The plumage is gray with a distinctive black cap with a fallen crest of two to three narrow white plumes at the back of the head. The heron has a black back and the face, throat, fore neck and belly are white. During the breeding season, the black feathers from the head and back emit a bluish-green gloss and the legs become red. Wings and tails are blue-gray and legs and feet are usually yellow. . Night herons receive full adult plumage in the third year. Members of the heron family are structurally characterized by having four toes. There are three toes facing forward and one facing to the back.

Black crowned night heron
Night Heron

 

DISTRIBUTION and HABITAT:

Black Crowned Night Heron Hamilton

Black-crowned night herons are found by marshes at night and by day they roost communally. Besides marshes, they inhabit wetlands, like ponds, swamps, tropical mangroves, streams, rivers, mud flats, and edges of lakes. They have even been found in rice fields and other agricultural habitats near water. Larger wetlands will have substantial colonies of black-crown night herons, whereas, they may be seen alone or in small groups by less significant bodies of fresh or salt water.

Night herons are distributed almost worldwide including North America,Southern Ontario,  South America, South Europe, Africa, South Asia, Falkland Islands, and Hawaii. The Black-crowned night heron is a rare visitor to Micronesia. In the Hawaiian Islands, the Aukuu can be found in all coastal wetlands. Black-crowned Night Herons are common winter breeding residents of the United States Gulf Coast.

 

BEHAVIOR:

Black-crowned night herons associate with other species of herons frequently and are socially active all year. These herons have a deep croaking call sounding like quark. Adult herons will defend their feeding and nesting area.

Adult Night Crowned Heron

Young Herons have an aggressive, regurgitating reaction to discourage intruders. The black-crowned night heron is usually a nocturnal feeder but it will feed during the daytime during the breeding season or when there is a food shortage. The black-crowned night heron is an expert at still fishing”. It can stand motionless for long periods in shallow water, on pilings, or on floating docks watching and waiting for its prey. A thrust of its bill into the water catches small fish. These herons can also swim when searching for food.

 

DIET:

Night heron finishing breakfast

The diet of the Black-crowned Night Heron depends on what is available, and may include algae, fishes, leeches, earthworms, insects, crayfish, mussels, squid, amphibians, small rodents, plant materials, garbage and organic refuse at landfills. They have been seen taking baby ducklings and other baby water birds. The night heron prefers shallow water when fishing and catches its prey within its bill instead of stabbing it. Herons will sometimes attract prey by the rapidly opening and closing the beak in the water to create a disturbance that attracts its prey. This technique is known as bill vibrating.

BREEDING:

Night heron slips

The Black-crowned Night Heron nests in colonies and produce one brood per season. During the mating season the male become aggressive and perform a mating display to attract the female. This consists of the male doing a snap display followed by an advertisement display called the stretch, or snap-hiss. During the snap display the male walks around in a crouched position, head lowered, snapping his jaws together or grasping a twig. Then the male stretches his neck out and bobs his head and makes a snap-hiss vocalization. Twig shaking and showing off may occur between songs. This show motivates other males to show off and display also. The displaying is successful if the male attracts a female to his nest site. At the time of pair formation, their legs turn from red to pinkish color.

NESTING:

Night heron slips

Mating takes place near the nest, shortly after pairing. The male begins the twig ceremony by presenting the female with twigs, which she works into a platform nest. The nests usually rest on a fork of a branch, in the trunk of a tree, in deep foliage, or in low bushes, and reed beds. The herons make a flimsy, haphazard, stick platform nest or they just rebuild an old nest. The nest is lined with grass and roots.

After four or five days a clutch of three to five eggs are laid. Both parents share in incubation, which lasts 24-26 days. The eggs are green the first day and become pale blue or greenish days later. On hot days the parents may wet their feathers to cool off the eggs.

Both parents feed the young by regurgitation of food. After two weeks the young leave the nest. They dont go far and for about three weeks can be found clustered at the top of the trees. By week six or seven they can fly well and follow the parents to the feeding grounds. Adults do not recognize their own young and will accept other young if placed in the nest.

CONSERVATION STATUS:

Not a good day to fish

In the 1960’s there was a decline in black-crowned night heron populations due to the use of DDT. The status of the heron population is indicative of environmental conditions, due to their high ranking within the food chain. Many herons are killed each year at fish hatcheries because the birds are considered a pest that prey on the hatchery fish.

 

Sources: honoluluzoo, Birds of America, Wikipedia

 

Doug Worrall Photographer

Endangered Spring Migration It’s All About Timing

Endangered Spring Migration It’s All About Timing

Monday March 14 2011

Red-Breasted Merganser

 

Just as scientists are beginning to answer basic questions about migration, many migratory birds and other animals are in trouble

Are you starting to see some of your favorite birds come back from their wintering grounds? As the seasons change, many bird species come and go in the natural phenomenon of migration. Today, scientists are just beginning to answer some of the most basic questions about migration. But a shadow hangs over their research: Many migratory birds—and other migratory animals–are in trouble.

MIGRATION BASICS

Waterfowl in danger

Spring Migration begins

Migration all year

What is migration? Many creatures wander, but only some are true migrants. Most biologists define migration as repeated seasonal movement between breeding and non-breeding grounds by the same individuals.

How far do birds migrate? Thanks to tracking devices, we now know the astounding distances that some migrating species travel. For sheer distance, nothing beats migrating birds. Sooty shearwaters astonished scientists by flying more than 40,000 miles in a loop from New Zealand to Chile, Japan, Alaska and California before a trans-Pacific trip back to New Zealand. The birds averaged more than 200 miles per day for 200 days.

Longest Known Non-stop Bird Flight: The real migration champ was a bar-tailed godwit that flew 6,340 miles nonstop between New Zealand and North Korea, where it rested briefly before continuing nearly a thousand additional miles to its breeding grounds in Alaska.

HOW DO BIRDS FIND THEIR WAY?

Migratory Birds

There are a range of techniques migrating birds use to navigate:

* Earth’s magnetic field: This was discovered by a series of experiments in the mid-1970s which reversed magnetic fields around songbirds, triggering them to fly the wrong direction. It is now known that some 50 species including birds follow magnetic pathways.
*Circadian clocks: innate temporal rhythms in the biochemical, physiological or behavioral processes of all living things, from plants to birds
*Internal compasses: Using the sun or stars as a compass to determine direction
*Smells: Some birds, including pigeons, use olfactory clues to find their way.
*Geographical features such as mountain ranges and coastlines. Most migrants seem to rely on a combination of these techniques depending on conditions.

Migratory bird
Some stay all year
First signs in north america

WHY SCIENTISTS NEED TO UNDERSTAND MIGRATION
“The nonbreeding season drives a lot of what happens during rest of the annual cycle,” says Peter Marra, a research scientist at the Smithsonian Migratory Bird Center at the National Zoo. That cycle’s middle stages—the actual travel—remain terra incognita to scientists. The sheer number of habitats used at different points during migration presents a formidable challenge to conserving migratory birds.

NEW TECHNOLOGIES TO STUDY MIGRATION
The recently announced ICARUS Initiative will launch a satellite devoted to migratory animals and develop tiny, powerful transmitters that will allow researchers to follow creatures as small as insects across broad stretches of time and space.

WHAT ARE THE THREATS TO MIGRATORY BIRDS?

The sights and sounds

*Habitat loss and degradation. The habitats of migratory species nearly everywhere are under pressure from deforestation, farming and expanding human populations. Human-made obstacles also hinder travel. In many cities, skyscrapers, for example, kill migratory songbirds.
* Global warming. Researchers are reporting new behaviors among migratory animals worldwide that may stem from changing climate—shifts in breeding ranges, mistiming of cues and departures, for example. “Since the wintering habitats are changing at different rates than more northerly habitats, things can get really of out sync,” says the Smithsonian’s Marra.

Out of whack: In the Netherlands, some populations of pied flycatcher have crashed because the birds are arriving from African wintering grounds too late to feast on a once predictable bounty of caterpillars. Higher springtime temperatures in Europe are causing the insects to hatch earlier than they once did.

CAN MIGRANTS ADAPT?

Trumpeter and Tundra swan native species
Mute Swans adapt well

No one knows. Recently, some birds have shown flexibility by changing routes or timing or breeding sites in response to new environmental conditions. In the Midwest, for instance, ducks are arriving later in the fall and resting longer before continuing south, perhaps in response to higher temperatures.

Along the east coast of Massachusetts, where temperatures are rising and the insects on which birds feed on hatching sooner, 8 of 32 migratory songbirds looked at have begun arriving earlier from their wintering grounds—primarily species that winter in the southern United States as opposed to farther away in the Tropics.

“But I think it would be dangerous to assume that all species can adapt,” says Princeton University ecologist David Wilcove. As Wilcove writes in his book No Way Home: The Decline of the World’s Great Animal Migrations, “The irony is that just as the phenomenon of migration is slipping away, we are entering a golden age for studying it.”

Spring Migration: It’s All About Timing

Timing and luck

From January to June, each migratory species has its own special time to return to summer breeding grounds
Somewhere in North America, there is probably some kind of migratory movement of birds every day. But spring migration—the mass movement of birds toward their breeding grounds—happens with predictable timing each year. The precise local timing varies, of course, with latitude and elevation. “Early spring” might mean early February in the southernmost states, late March or early April in the north, or even May in the far north and high mountains.

Mass Migrations

Among the first groups of birds to move north are waterfowl: ducks, geese, and swans may begin migrating as soon as frozen lakes and marshes start to thaw. Even in the northern Provinces, flocks of waterfowl may arrive in late February. Also on the move this early are some species that migrate mostly within North America, spending the winter as far north as they can. They include killdeer and red-winged blackbirds.

Some birds of prey also start to migrate in early spring. Bald eagles, rough-legged hawks and red-shouldered hawks are actively moving north even while wintry conditions still prevail.

Other surprisingly early migrants include purple martins, returning from South America and reaching Florida and Texas by late January and making it to northern states by the end of March.

Blue heron nesting zone

Many native sparrows tend to be early migrants, with large numbers moving in southern states in March and in northern states by early April. Kinglets and sapsuckers are in this moderately early wave as well. And most blackbirds move north during the first half of the spring.

 

Shorebirds (sandpipers, plovers and their relatives) have a protracted migration, with some species represented among the earliest and latest migrants. Pectoral sandpipers and American golden-plovers, wintering in South America, come back to southern provinces by the end of February and reach northern provinces by March. Many other species migrate later, with peak passage in most areas during April and May. Long-distance migrants that winter in southern South America, white-rumped sandpipers peak in  central Canada and  United States in late May or early June.

Southern Ontario

 

The great northward flood of songbirds that have wintered in the tropics—including warblers, tanagers, buntings, grosbeaks, orioles, vireos and thrushes—occurs primarily during April and May, filling North American woodlands with color, song and activity. For many birders, warblers are particular favorites; there are several places in the country where you can see more than 30 species of these tiny, colorful gems during the course of the season.

Deer Migration Huge

By early June, aside from a few shorebirds and straggling songbirds, spring migration is over across most of North America. This is when birders turn their attention to local nesting species—and get ready to watch for the first of the fall migrants, which in some areas start showing up by early July.

New Born signet
Mute swan
Refections of spring

Sources: National Wildlife Foundation, Wikipedia

 

Doug Worrall Photography

Trumpeter Swan Population in Ontario Rising

Trumpeter Swan Population Rising in  Ontario

Thursday October 14 2010

Numbered Trumpeter Swan

Volunteers Report Trumpeter Swan Wing Tags – Revealing a Self-Sustaining Population in Ontario

A team of vigilant observers has helped biologist and TTSS board member Harry Lumsden to track and tally what is now a successful, self-sustaining population of Trumpeter Swans in Ontario.  Ontario’s Trumpeters are marked with yellow wing tags. In a typical year, observers report 300-360 individuals. Once a number is read and reported, the data can be entered to help track that bird’s movements, habitat use and reproductive success. Data from tagged bird sightings allows biologists to produce a genetic family tree and to record population growth and range extension. This past year 116 birds were marked in Ontario — 70 of them caught by hand by the team of Bev and Ray Kingdon, Julie Kee and Kyna Intini in the wintering flock that feeds at La Salle Park and other areas near Burlington on the west end of Lake Ontario. Peak numbers recorded for this wintering group were 160 Trumpeters along with 100 Mute Swans. Smaller congregations, where other birds were marked, included Bluffer’s Park, Frenchman’s Bay, Whitby Harbour and Wye Marsh.

Tag sightings by observers across the southern part of the province proved useful even when the number was not recorded. Ontario observers have been asked to keep track of the proportion of marked to unmarked birds in groups observed (even if number is not read). The last four year’s analysis of reported proportions reveals a steady increase in the wild population. As the population grows, the percent of total marked birds has declined. In 2005, it was 54%. By 2006 it had declined to 46%, 2007, 44% and in 2008, 39%. In 2007-08 364 tagged birds were reported. By using this calculated annual percentage rate, with an adjustment for marked birds missed (based on year to year variance in reports of known live tagged birds) along with the percentage ratio of marked to unmarked birds, biologists estimate the population.

Trumpeter swan

Doing the numbers, Harry Lumsden recorded quadruple figures for the Sept. 2007 to Aug. 2008 report — a total of 1018 birds.  The milestone of 1000 birds had been passed!  This number is for adult and sub-adult birds. Cygnets of the year averaged 39% for this period. Applying this ratio to overall numbers, Ontario’s breeding population estimate registers a remarkable 1415 birds. When Harry Lumsden started Ontario’s Trumpeter Swan Restoration program in 1982, Trumpeters had not been seen for almost 100 years, since 1886 when a hunter at Lake Erie’s Long Point shot the last known individual. The Ontario Field Ornithologists honored Lumsden with their Distinguished Ornithologist award for 2008. Among his many career achievements, leading the successful restoration of Ontario’s Trumpeter Swans must bring great satisfaction.

From

Trumpeter Swan Society

Photography Doug Worrall