Hacking Tower

Photo: www.suttoncenter.org

Re-Introduction of Eagles

Start of Project - Restoration Techniques - Success in New Jersey - Eagle Monitors - Midwinter Survey

the start of the project

When it is time for eagles to breed, they are known to return to the general areas where they fledged. Therefore, the biologists needed to convince some eagles that they were born in New Jersey. In 1982, they began to manage the one remaining nest. They began by climbing the tree and removing the egg(s). One of the effects of DDT is thin eggshells and the eagles were unable to incubate the eggs. Because chickens weigh less than eagles, they were used to incubate the eggs and 10 day old chicks were carried up the tree and placed into the nest. The eagles quickly accepted the chicks and raised them successfully.

This process would have been too slow to make a significant change for the state population. The mortality rates in young eagles can be as a high as 80% and eagles are not ready to reproduce until they are 5 years old. Therefore, a hacking project was initiated in which young chicks, mostly from Canada, were brought to the area of New Jersey that has good bald eagle habitat, and raised in cages on stilts, called hacking towers. The chicks never saw the humans that provided them food. About sixty chicks were fledged that way between 1983 and 1989.

eagle restoration techniques

The first effort to restore a bald eagle population was made in 1974 in Maine. Two eggs from wild nests in Minnesota were placed in nests in Maine.

The three usual methods for reestablishing nesting pairs are egg transplants, fostering and hacking.

Hacking was first tried in New York State in 1976 and has been the most successful method of bald eagle re-introduction. This method is still being used today in parts of the country that are attempting to increase their population.

It is important to chose a good hacking site, one where there is an abundant fish supply for fledged birds. It is generally considered important to use areas where bald eagles historically nested and that still have enough undisturbed habitat to support nests.

The Eagle's Advocate presents details about the requirements for successful hacking.

success in new jersey

In 1988, a second eagle nest was discovered in New Jersey. Since then, the population has increased and in 2003 there were 40 nests with 41 young.

2004 Numbers just out -- 44 nests with 54 eagles fledged!

the eagle monitors

The great part about this program is that anyone can become a monitor. It does not require a lot of birding knowledge or a background in biology. All that is required is enthusiasm and dedication and once someone spends even a brief time observing eagles, they quickly gains those two qualities. The state provides training materials that describe eagle behavior and what is expected of the monitors.

The group of monitors includes a range of people. A number of them are retired citizens who have decided to spend a lot of their time monitoring their bald eagle nests. Others are like me, with a full-time job that is unrelated to the project who observe mostly on the weekends. Most of the monitors continue with the project for years.

I first learned about the project through a write-up seeking volunteers in the NJ Audubon magazine. Many of the monitors come to the program through word of mouth. This bald eagle monitoring project is a very successful program and the state biologists assert that a key component of the project are the volunteers.

mid-winter eagle survey

The ENSP works in conjunction with New Jersey Audubon to survey the eagles in mid-winter. This survey is generally performed the second weekend in January. The eagles that are in New Jersey in the winter are not necessarily resident eagles. Some eagle pairs stay at their nest areas all year, others travel further south to find places with more open water and thus, more fish. Eagles are social birds and sometimes form communal roosts near water consisting of several birds. The survey is part of a nationwide winter survey of eagles that takes place in the first two weeks of January and usually consists of two consecutive days of observation.

The first survey in 1978 found less than 10 eagles in the entire state.

178 bald eagles and 9 golden eagles were counted in the 2004 survey.