People often wonder if any of the conservation measures including rules, regulations and laws that are put into effect actually do anything. One of the best cases of conservation success that comes to mind is that of several birds of prey including the osprey, bald eagle, and peregrine falcon.
Habitat destruction is the major driver of species loss (species extinction), but other stressors such as hunting or wildlife trade, disease and pollution also lead to species loss. Habitat destruction and hunting were impacting bird of prey populations in the early 1900’s. However, it was the negative impacts of certain pesticides and pollutants that is believed to have brought populations of these birds to the brink. In the early 1900’s new pesticides were found to be useful against a wide variety of pest species (they were broad spectrum). DDT (Dichlorodiphenyltrichloroethane) was used during World War 2 to successfully prevent the spread of insect borne diseases such as malaria and yellow fever and is credited for the eradication of malaria in the U.S.. However, between the 1950’s to 1970’s several bird species’ populations crashed, particularly birds of prey such as the osprey, bald eagle, and peregrine falcon as well as the brown pelican. It was estimated that between New York and Boston during this time that 90% of nesting pairs of ospreys disappeared. Studies found that this pesticide would accumulate in the tissues of animals that ingested plants or insects that had been sprayed. Predatory birds eating these smaller animals would thus accumulate larger and larger loads of this pesticide, leading to either poisoning or reproductive failure. It was discovered that DDT led to the birds’ eggshells becoming too thin, causing eggs to crack and leading to the death of the embryos and young birds. Since no young were being hatched (reproductive failure, no new birds were able to replace the older birds (i.e. there was a decline in recruitment), and thus populations of these species rapidly declined.
With the discovery of the connection between DDT and inability of these species to successfully reproduce, DDT was banned in 1972 in the U.S., Canada and parts of Europe. Unfortunately, by this time the populations of these species were so low in number, that all were placed on the U.S. federal Endangered Species List. This listing afforded additional protections of these species. The listing of these species as endangered and the reduction in DDT usage enabled the species to recover.
Since then, populations of these species have rebounded. For instance, bald eagle populations in the lower 48 states of the U.S. are estimated to have over 10,000 nesting pairs today, compared to the less than 500 nesting pairs in the 1960’s. All three raptor species have been downgraded or completely removed from the Endangered Species list. Osprey were placed on the list in 1976 and downgraded to species of special concern in 1999. Peregrine falcons were listed in 1970 and delisted in 1999. Bald Eagles were put under protection in 1967 and removed from the list in 2007.
If you are unfamiliar with them, osprey (Pandion haliaetus) are large hawks, with distinctive coloration, a dark eye stripe and bright yellow eyes. They can be found worldwide on all continents except Antarctica. Within the U.S. they can be found along costal areas and estuaries, including the Great Lakes region and even along large rivers and wetlands. They feed almost entirely on fish. They can be seen hovering over water searching for a tasty fish and then plunge feet first to grab their meal. The build large stick nests usually on top of poles or dead trees near or over water.
Growing up, I remember the excitement whenever someone said they saw a bald eagle, peregrine falcon or an osprey. These were rare and endangered species, so seeing one was a big deal. In college and beyond, the reports of sightings grew and now they are really rather common place. For instance, while visiting a dog park in Florida this winter we saw a bald eagle soaring above us, then it swooped down maybe 20 feet from us and landed briefly. Not exactly sure what he was doing, but he took off soon after that. In Utah, there are signs on the road to look out for eagles…. eagles will often scavenge food and can often be seen at road kills especially in the winter, so the sign are a warning to be on the look-out for a road kill eating eagles, to avoid hitting them. Where I live now, I would see them daily at my place of work during the spring and summer. As for osprey I have seen them in Florida and as far north as Alaska. Check out these pics from Florida, I could not count how many osprey nests we saw, there were so many.
These species show that the Endangered Species Act and other regulations and laws do work, and when given a chance, species can make amazing recoveries.
Leave a Reply.
Write something about yourself. No need to be fancy, just an overview.