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