It is that time of year for one more time. The time when the year list resets to zero, Big Years start and end, and the ABA announces its new bird of the year. This year, the powers that be have decided that the 2015 bird of the year shall be…wait for it…Green Heron! This bird is a familiar sight along waterways throughout much of the ABA Area. Despite being fairly common throughout their range, they are a furtive species and can be easily missed by one not paying good attention.
To me, Green Herons remind me of marshes throughout North America. Thinking about them takes me back to birding in Florida, as they are one of the many herons and egrets that call that state home. They also make me think about seeing them in my home state of Pennsylvania fishing and flying around a small marsh not too far from my house. Whatever memory they invoke, it is always a good one as they are one of North America’s most interesting wading birds.
Green Herons mostly eat small fish. However, they are fairly opportunistic and will eat anything from small rodents to insects. Another facet of their opportunistic life is their exploitation of “superabundant food sources, such as breeding frogs” (Animal Diversity Web).
Green Herons mostly catch their aquatic prey in typical heron fashion, waiting for it to come close before lunging forward and capturing it. They prefer to forage in shallow water where they are the most successful at catching prey. However, they have been known to dive into deeper water from above before swimming back to shore with their catch. However, this kingfisher-like method of foraging is not very successful and is therefore not often performed.
Green Herons breed across the eastern, Pacific coast, and southwest portions of the United States. They also breed in small sections of southern Canada. The male will begin to build the nest before finding a mate. After finding one, he leaves the rest of the construction to the female. Nests are typically placed in a tree or a shrub, often concealed with branches. Green Herons mostly nest near a source of water (and therefore food). However, they sometimes nest as much as half a mile from the nearest water source. While typically a solitary nester, they occasionally raise their young in colonies.
One of the most fascinating things about Green Herons is that they are one of the few bird species documented using tools; some of them use bait to catch fish. The bait is often a piece of bread or something similar, but they have also been seen using live prey (which they seem to have high success with) and other types of lures (Animal Diversity Web). They place the bait in the water and wait for it to attract fish. When a fish comes in, the heron lunges and, if it’s lucky, catches the fish. Interestingly, this behavior seems to be most often performed by herons fishing in deeper water where there is less to conceal the heron from its prey (Higuchi).
Some people think that Green Herons learned this behavior by imitating humans. However, this seems unlikely since attempts to teach Green Herons this type of fishing have failed. Another theory is that they see an object in the water attracting fish and make the connection that they could drop an object into the water intentionally (Animal Cognition Home Page).
Whichever theory is true, the question still remains as to why this behavior is so rare. Again, there are two theories. One is that because it takes a large amount of intelligence to learn this behavior, only exceptionally intelligent herons learn it. The other theory is that so few herons learn to forage in this way because not many have the opportunity to watch an object in water attracting fish (Animal Cognition Home Page).
While Green Herons are not the only bird species which fish in this way (in fact six other heron species have been shown to occasionally do it (BBC) they are the species which is most documented foraging in this manner. It is one of the many things that make these small herons interesting.
Being a fairly common bird throughout its extensive range in the ABA area, it might come as a surprise to many birders that the Green Heron population is in a decline. The population actually dropped by about 50% from 1966 to 2010 (All About Birds)! While historically Green Herons have been hunted and they are still sometimes killed by fish hatcheries for eating the fish (Animal Diversity Web), the biggest threat to Green Herons is from destruction of their wetland habitat. However, the heron remains fairly common and the declines have not been major enough to cause widespread alarm.
Over most of the ABA Area, a Green Heron is a familiar and welcome sight. Their unique life history and penchant for tool use makes them a fascinating sight as well. Whether they are feeding along a slough in Florida, flying briefly by in a wetland in Pennsylvania, or resting by a pond in Arizona, they are always a pleasure to spot. It is a fantastic choice for bird of the year and face of North American birding in 2015.
- Animal Diversity Web: Green Heron
- All About Birds: Green Heron
- Green Heron captured using bread as fishing bait in astonishing show of deferred gratification
- Individual differences in bait-fishing by the Green-backed Heron Ardeola striata associated with territory quality, Hiroyoshi Higuchi (1986)
- Animal Cognition Home Page: Green Herons fish with bait
- BBC: Super Smart Animals