Little blue herons stalk their prey

The Little blue Heron (Egretta caerulea) is a part-time resident of Maryland, preferring the coastal areas around the Atlantic Ocean and Chesapeake Bay.

It's a medium-sized bird, about 20 inches tall, with a wingspan of about 3 feet. This bird breeds in subtropical swamps around the Gulf of Mexico, Atlantic Ocean and Caribbean. Little blue herons nest in colonies, often in conjunction with other species or herons, egrets and wading birds.

Young little blue herons have a white coloration that they retain for about one year; then their plumage turns to a uniform slate blue color. They are the only species of heron that have this distinct color difference between juveniles and adults. The white-colored juveniles often intermingle in large colonies of snowy egrets; this is advantageous because they can out-compete the smaller egret for food, and they are less susceptible to predators in these large flocks. This nondescript color phase helps ensure the survival of the young bird.

Credit: - Dr Thomas G Barnes, USFWS

Little blue herons stalk their prey in shallow water, oftentimes running about as they do so. The heron feeds on fish, frogs, small crustaceans and insects.

In the last few years, amphibian, salamander and turtle populations have been noted as declining. Several factors contribute to the decline of these species, including a chytrid fungus, habitat destruction and the viral infection from ranavirus.

Declines in amphibian populations have mainly occurred in the Western U.S. and in South America. Habitat destruction is starting to be controlled in Maryland though stricter laws such as the state Forest Conservation Act and enforcement of sediment control regulations. However, Maryland is one of the states with the highest numbers of observed ranavirus deaths in amphibians, salamanders and turtles reported to the U.S. Geological Survey, National Wildlife Health Center.

Ranavirus infections in these species are believed to have a basis in animals sold in the market place, often by mail. The larval and tadpole amphibian stages appear to be most susceptible to the virus, with infected tadpoles observed to be floating or not swimming properly. Several times the normal death rates for Eastern box turtles, which normally can live up to 50 years in the wild, have been observed from ranavirus infections during the last two years in neighboring Montgomery County.

Box turtle symptoms include mucus discharge, swollen eyes and trouble breathing. Turtles are believed to have picked up the infection from amphibians. These animals help control insect populations. The prolific amphibians are also a part of the diet for many species of birds, rodents and other animals. Their reduction in numbers can influence increases to local insect populations and reduce populations of other wildlife.

As spring arrives, and our youthful scientists collect tadpoles for observation of their transformation into frogs, the Maryland Department of Natural Resources notes that there are steps that can be taken to minimize the spread of this virus. While up to 25 tadpoles by species can be in the possession of an individual, DNR also recommends that nets and aquariums be sterilized for 10 minutes with a 10 percent bleach solution before collecting, and that any frogs be returned to the same place the tadpoles were collected.

Stay clear of handling turtles, frogs and salamanders with abnormal appearances.

Article by FCFCDB

Nature Notes for 2/26/2012