Duck hawk peregrinations

  Healthy immature, male Peregrine falcon just before release after 2 months rehabilitation from broken humerus and emaciation. Dec. 3, 2015. Photo curtsey of Jessica Zorge, Cummings School of Veterinary Medicine at Tufts University

  Healthy immature, male Peregrine falcon just before release after 2 months rehabilitation from broken humerus and emaciation. Dec. 3, 2015. Photo curtsey of Jessica Zorge, Cummings School of Veterinary Medicine at Tufts University

     In the previous blog I wrote about an injured Peregrine falcon that had been found on the Island, and for which, rescue was underway. I noted that:

 “It took all of us to form a chain of survival that has resulted in a lost Peregrine recovering in a clinic with a pinned broken humerus and gaining weight; while we – the human species – looked forward to its hoped-for release in a few months time.

     During the time between its rescue and its release I have learned some interesting facts about Peregrine falcons.

     First, the nomenclature: in an earlier era they were known as Duck hawks (their primary food is other birds, especially waterfowl), or sometimes called Ledge hawks (their natural nesting sites are high craggy ledges). The genus species name, Falco peregrinus, is also enlightening. Falco is related to the Latin word, meaning sickle, referring to the sharp arc of the bird’s wing shape, and peregrine means wanderer or traveler. Some subspecies have exceptionally long migration routes; for instance Falco peregrinus tundrius breeds in the North American arctic and Greenland, and winters in Central and South America. Peregrine falcons, for centuries, have been favored hunting birds used by falconers. However, because of their inaccessible nesting sites, the birds could only be acquired during their peregrinations away from the breeding grounds, and thus became known as Peregrine falcons.

     Most sources identify nineteen subspecies of Peregrine falcon worldwide, three of which are in North America: Falco peregrinus tundrius (Arctic Peregrine falcon) of the Arctic tundra and Greenland; F. p. pealei, (Peale falcon) of the Pacific northwest; and F. p. anatum, (American Peregrine falcon i.e. Duck hawk), which is found throughout Canada and the United States.

      Falco peregrinus tundrius is of special interest to us here on Block Island. Smaller and lighter in color than the continental Peregrine falcon (F.p. anatum), this subspecies is easily identified by its obvious white forehead and large white ear patches – this is the subspecies of the traveling Peregrine falcon that was rescued this fall (see photo).

     In addition to the success of the individual Peregrine rescue this fall on Block Island, there is the success of the rescue of the species itself to be cheered. American and Arctic Peregrine falcons were listed in 1970 as endangered species under the U.S.’s Endangered Species Conservation Act of 1969. Prior to 1940 the American Peregrine falcon, numbered about 4,000 nesting pairs throughout North America. Due to the affects of DDT and other toxic pesticides the western population of Peregrines had declined by 90 per cent, and the northeastern population was extirpated by 1970. (Other subspecies worldwide were also threatened by the use of DDT.) In 1975 there were 324 known nesting pairs of American Peregrine falcons in North America. Again, because of the actions of many – which put in place the Endangered Species Act in 1973, the banning of DDT in 1972 for most uses in the U.S., and the establishment of a multipronged Peregrine recovery program – American Peregrine falcons were taken off the Endangered Species list in 1999. (Arctic Peregrines were removed from the list in 1984.)

     The decline and recovery of American Peregrine falcon populations is well documented. What is a little less clear, are the numbers of nesting Peregrines and traveling (migrating) Peregrines prior to the precipitous decline starting in the 1940s. In the discussion of the range and distribution of Duck hawks, Edward Howe Forbush suggests, in his Birds of Massachusetts and Other New England States (1927), that there was not a definitive accounting of the presence of Peregrines in New England, largely because their nesting habitats are relatively inaccessible and had not been widely explored. Forbush reports that in all six New England states Peregrines: are “rare local summer residents”, breed in the mountain ranges of states where they exist, and are rare or uncommon migrants, “chiefly coastwise”.  Forbush had a cadre of informants that corresponded with him and contributed information about bird species throughout New England. The discussion of Duck hawk distribution in Rhode Island relies almost exclusively on Elizabeth Dickens. “Rhode Island: Rare migrant, chiefly coastwise; ‘very common both spring and fall, 46 in fall of 1917’ (Miss E. Dickens), Block Island.” (Forbush, 1927).

     How lucky we are to have the Island as the epicenter of Elizabeth Dickens’ fifty-plus years of bird observations. And luckier still, to find that she has been followed by a long line of dedicated birders and recorders of observations. The newest example is the Biodiversity Research Institute (BRI) team of raptor banders. This group has set up a fall raptor banding station less than a mile from Elizabeth Dickens’ house, and has been banding, and in some cases attaching transmitters to, raptors since 2012. One hundred years after Elizabeth Dickens started collecting daily bird observations (E. Dickens journals start in 1912 and end in 1963), the BRI team is collecting information in a completely different historical context, but the landscape of the southwest corner of the island has changed only slightly. The BRI effort to collect information about passing raptors is more proactive than that of a single woman going about her daily 20th century farm life, making notations of what comes her way. However, I find that I cannot resist presenting some of the numbers of these raptor observations, separated by nearly a century, if for no other reason than to honor the work of both BRI and Elizabeth Dickens.  The recorded observations of each, adds to the value of the other’s.

   These numbers represent raw data only. Elizabeth Dickens (ED) numbers are the sum of these species recorded in her journals in 1916 and 1917 for the months of September and October. The Biodiversity Research Institute (BRI) numbers represent the number of these species banded in 2012-15 during September and October. BRI numbers do not include individuals of the species that may have been seen, but not banded.

   These numbers represent raw data only. Elizabeth Dickens (ED) numbers are the sum of these species recorded in her journals in 1916 and 1917 for the months of September and October. The Biodiversity Research Institute (BRI) numbers represent the number of these species banded in 2012-15 during September and October. BRI numbers do not include individuals of the species that may have been seen, but not banded.

The following resources were used in the research of this article:

Elizabeth Dickens Journals, housed at the Audubon Society of Rhode Island, 1912-1963

C. Persico, BRI, personal correspondence

Birds of Massachusetts and Other New England States, Edward Howe Forbush, 1927

The Sibley Guide to Birds, David Allen Sibley, 2000

https://www.fws.gov/endangered/esa-library/pdf/Peregrinefactsheet.pdf