An online resource based on the award-winning nature guide

Herons

Tadpole Maturation

5-22-19 green heron and tadpole _U1A1148The eggs of Wood Frogs, the earliest species of frog to breed in the Northeast, are just hatching and tiny Wood Frog tadpoles can be found swimming about at this time of year. This Green Heron is devouring a tadpole, but it is anything but tiny – certainly not a Wood Frog tadpole. How can this be?

The answer is that the tadpole that the Green Heron caught did not hatch this spring – it hatched last summer. Unlike Wood Frogs and Spring Peepers that mature in roughly two months, Green Frogs and American Bullfrogs can take two or even three years to metamorphose into adult frogs. By their second summer they are of substantial size. The Green Heron has caught a Green Frog or Bullfrog tadpole that has overwintered and would probably have matured this summer.

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Great Blue Herons Building & Renovating Nests

5-6-19 great blue heron with white pine2_U1A7932A visit to a Great Blue Heron colony at this time of year will be rewarded with a great deal of avian activity, for their nesting season has begun and renovations are going full tilt. Males usually arrive first and settle on nests (more often as not using a different nest from last year) or begin building their own. Courtship then begins.

Great Blue Heron nests are found primarily in trees, up to 60 feet or more above the ground. Where trees are not available, herons will nest on the ground (usually only on predator-free islands). Males gather sticks and other nesting materials from the ground, nearby trees and shrubs, or from unguarded and abandoned nests, and females are usually responsible for the placement of the sticks into the nest. Nests are often reused for many years. Pictured is a Great Blue Heron returning to its nest with a branch from a White Pine tree which will be used for lining the nest. Nesting material is added throughout the nesting period.

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Great Blue Heron Chicks Enjoying Home Delivery

7-18-18 gbh chicks & parent IMG_5874Great Blue Heron chicks spend roughly two months in their nest before fledging, during which time they are totally dependent on both of their parents for food.  During the first week after their eggs have hatched, the parents return to the nest after foraging and stand on the rim while placing regurgitated food into their chicks’ open beaks.  By the second week the chicks grasp the adult’s beak briefly when the parent arrives with food, and by the end of the third week the chicks are pulling the adult’s beak into the nest, which they continue to do until they fledge.  Occasionally chicks reach into an adult’s open beak to get food, but most of the time the parents put the food into their offsprings’ beaks.

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Fishing Methods Of Birds With Spear-shaped Bills

10-10-17 great blue heron with fish 049A5631How do herons, egrets, bitterns, kingfishers, loons and other fish-eating birds with spear-shaped bills capture their prey? Do they use their bill as a spear and pierce through a fish, or do they grab the fish between their mandibles? You often read about one of these birds “spearing” a fish. However, a majority of these birds, most of the time, do not spear fish, but open and shut their bills fast enough to capture a fish in them — the spear shape of their bill lends itself to the tong-like action it performs. In addition, its shape enhances the movement of the bill through the water as the bird dives (its head or body) into the water to grasp the fish between its upper and lower mandibles.

One exception to this rule is the Anhinga, which does run its bill (which is equipped with backward grooves to prevent slippage) through fish in order to capture them. After spearing a fish, an Anhinga then shakes it vigorously off its bill, tosses it in the air, and catches and swallows it headfirst. (Photo: Great Blue Heron)

 

 

 


Green Heron Feet

8-9-17 green heron feet2 049A1710The structure of a Green Heron’s foot lends itself to a life of wading at the water’s edge while foraging for food and not sinking into the sand. Three long toes pointing forward and one pointing backward create a considerable amount of surface area, and the more the surface area the less pressure that is placed on the sand. Webbing between its outer toes adds to the snowshoe effect (and also aids the heron when it dives below the surface of the water for prey and must swim back to shore).

This foot structure comes in handy when wading in shallow water, standing on emergent vegetation or perched a low-hanging branch at the water’s edge. As testimony to this, the pictured Green Heron spent an entire morning navigating from water lily pad to water lily pad foraging for fish, insects, frogs and other aquatic life.


Snowy Egrets Becoming More Colorful

4-18-17 snowy egret 053

For those New Englanders fortunate enough to live on the coast, Snowy Egrets are a welcome sight this time of year as they return from their wintering grounds to breed. Like most herons and egrets, they acquire plumes – long, wispy feathers – on their back, neck and head during the breeding season. (These plumes were highly sought after by the women’s hat trade in the late 1800’s and early 1900’s. They were valued at $32 per ounce, twice the price of gold at the time. Eventually laws were passed to protect the birds.)

Something slightly more subtle but equally as dramatic as ornate plumage highlights the appearance of these birds in the breeding season and that is a change in bill and feet coloration. Different species of herons and egrets exhibit different color changes. Snowy Egrets’ greenish-yellow feet turn a much richer orange-yellow hue during the breeding season, and the patch of bare skin at the base of their bill (lore) changes from a yellowish color to a pinkish/reddish color, only seen at this time of year.

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Silver Lining to Low Water Levels

9-27-great-blue-heron-20160911_7746The low water level of most small ponds and streams this fall has at least one silver lining, and that is that consumers of fish and other aquatic creatures expend far less energy finding prey, for it is all concentrated in much smaller bodies of water. The few puddles of water in small streams contain a vast amount of life, as do small ponds.

The Great Blue Heron has the advantage of having a varied diet that is found in a variety of habitats, so it forages in grasslands, marshes, intertidal beaches, riverbanks and ponds. While amphibians, invertebrates, reptiles, mammals, and birds are all known to have been eaten by Great Blue Herons, fish are their mainstay. They often forage in ponds, where they typically wade or stand in wait of prey in shallow water, which has not been in short supply this summer and fall. While the low water level is wreaking havoc with beavers and muskrats, it provides bountiful fuel for herons, egrets, kingfishers and other birds that forage in small ponds and streams as they wend their way southward.

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