Heron and Egrets

This tool lists various Habitat Fact Sheets developed by the Region 5 Regional Response Team. To suggest additions to this tool, please contact Barbi Lee. Click here for Inland Response Tactics Manual and  Submerged Oil Recovery Tactics.

A heron covered in oil Heron/egret in leghold Great Blue Heron Great Egret Cattle Egret Grey Heron

I. Species Description

Herons and Egrets are birds that belong to the family Ardeidae which contains around 60 species of birds. Herons range from 3-6 lbs and a height of 3-6 feet with a wingspan of up to 91 inches. Egrets are smaller and range from 2-2.5 lbs. and a height of around 3.25 feet and a wingspan of 59 inches. Herons and egrets are distinguished by their long thin legs,” S” shaped necks and long beaks. Their feathers range from blue to white and grey depending on the species. 

Herons and Egrets can be found all over the world. In the Americas, they can be found anywhere in the continental US. They can be found as high as Southern Canada and as low as South America. Herons and egrets that live in the northern US and Southern Canada migrate to southern states or even as far as South America in the winter to avoid freezing waters and to find ample food. Their habitats are always around water, but most species prefer swampy areas. They tend to live by shallow water such as lakes, ponds, and marshes. 

These birds have a carnivorous diet. Their main sources of food come from smaller animals in the water such as fish, mollusk, crayfish, and insect. They have even been known to eat larger animals like mice, frogs, and snakes. These birds are solitary hunters and only eat live prey. 

Herons and egrets are very common and are listed as species of least concern. Egrets have an average life span of around 15 years while herons can live anywhere form 15-20 years. Their mating season last between April to May. Although these birds are mostly solitary, they come together during this time and live together. The communities these birds live in are referred to as either heronries or rookeries. Their nests are built high above the ground in either trees, cliffs, or bushes. The eggs take several weeks to hatch, then by midsummer the parents and chicks separate.


II. Sensitivity to Oil Spills

Herons and Egrets, like most birds, are most affected by oil when it contaminates their feathers. Oil will make their feathers no longer waterproof and will cause them to sink. They will also be too heavy to fly. In addition, they will not be able to control their body temperature.

 Preening of the feathers will result in the ingestion of oil. In addition, these birds can ingest oil when eating prey that has been contaminated with it. This can result in such health problems as amenia, dehydration, lung, liver and kidney damage, ulceration, diarrhea, and damage to their immune system. Oil ingesting can also lead to neurological failure and chemicals in the oil could result in cancer throughout the body.

 When covered in oil, these birds will hyper fixate on preening causing them to forego necessary tasks resulting in starvation drowning and make them more susceptible to predators. The birds will have an increase in metabolic rate to combat hypothermia which results in the need for more food. When a bird covered in oil sits on their eggs, this can result in damage to the eggs. Even a single drop of oil on these eggs will result in birth defects.


III. Sensitivity to Response Methods

The following text describes potential adverse impacts to this species and its habitat resulting from various oil spill response methods and provides recommendations to reduce impact when these methods are implemented. This is not intended to preclude the use of any particular methods, but rather to aid responders in balancing the need to remove oil with the possible adverse effects of removal with respect to bald eagles. More detail about the response methods themselves can be found in the Inland Response Tactics Manual