Examining 'pellets' can tell you what a bird has been eating
March 21. 2014 7:07PM
An interesting mid-February letter was received from a reader in Weare who wrote: "I recently sent you a letter in which I talked about a large hawk that has stayed around my fields since last spring. I have spent much time with my binoculars and bird books, and in spite of my color blindness, I am quite certain that we have a red-tailed hawk.Quite interestingly, I found a large deposit of scat under the hawk's favorite pine tree that looks like mole remains. I snow shoed around the field and found numerous mole trails on and just under the snow pack that ended with a very distinctive and obvious imprint in the snow where the hawk's wings had left markings as the bird attempted to capture its prey. l did, on one occasion, see it swoop down onto the snow. I haven't seen it since Feb. 9, the last day of the NH Audubon Backyard Winter Survey."
The word "scat" usually refers to common "droppings." However, in the case where what appears to be small balls of bones, feathers and the like are referred to as "pellets" that have been vomited before the bird's next meal.
Simply put, a "pellet" is a mass of undigested parts of a bird's food, usually consisting of fur, feathers, bones, bills, claws and teeth of small mammals and birds eaten by hawks, owls, eagles and smaller birds. Those species are perhaps the best known for regurgitating pellets, but there are many species of birds world-wide that are known for this practice. M. Knight (1964) reported that at least 60 species of British birds eject pellets.
The pellets of hawks and owls are usually gray or brown in color. They may be spherical, oval, oblong or plug-shaped. Pellets vary from an inch or two in length in a large bird of prey to a half-inch in a small songbird. Experimental studies by Smith and Richardson (1972) suggested that pellets are created in the bird's gizzard within six hours after a meal. It appears that a raptor must cast a pellet before it eats its next meal.
Mrs. Bessie Price Reed, in an article in "Auk" magazine in 1925, reported on her studies of great horned owl pellets as follows: "... they never contained any other material save feathers, hair, fur, and cleanly polished bone. Microscopic evidence showed that hair and feathers were no way affected by the digestive juices, although the quills of larger feathers were always splintered and rolled together. On a number of occasions pellets were found that contained hair of two different colors or hair and feathers in which the masses were not mixed at all but were very sharply delineated, indicating that two portions swallowed at different times were not mixed together."
In more recent studies, pellets have been found to contain such additional items as bills, claws, teeth, insect skeletons, crustaceans and indigestible parts of plants.
Here at the farm for the past several winters, we have had what we refer to as a "year-round resident red-tailed hawk." We haven't seen it as often this winter as in previous years, but it usually has appeared once a week. This bird also has a favorite white pine tree fairly near the outlet of our now "abandoned" beaver pond. Beneath that tree we have frequently collected "pellets" and have examined them to see what "Brother" red-tail has been eating.
Chris Martin of NH Audubon has reported that New Hampshire's portion of the 2014 National Mid-winter Bald Eagle Survey Day has again set a new state record high for the number of bald eagles seen. Faced with freezing rain and glare-iced roads over most of the state on the observation date Jan. 11, 2014 many dedicated observers rescheduled their "Survey Day" to Jan. 12, 2014 which found 76 volunteers who located 67 individual eagles, eclipsing the previous high of 61 birds, roughly a 10 percent increase. The Lakes Region observers tallied 20 eagles; the Connecticut River region found 19 eagles, and the Merrimack region was third, with 14 individuals. Martin reported this was the 34th consecutive year that NH Audubon has coordinated New Hampshire's part of the National Mid-winter Bald Eagle Survey. (Starting with the winter of 1980-81.) This year on "Survey Day," the observers found 41 adult bald eagles and 26 immatures exceeding previous records of 61 in 2009, 2010, and 2013.
The official "Survey Day" occurs within a more inclusive two-week "count period" which this year spanned the interval from Jan. 1-15. During this year's Count Period, 83 bald eagles were found (51 adults and 32 immatures), one less than the state's record high of 84 bald eagles for last year's count period. As for overall long-term trends, the number of eagles counted in the Granite State has been doubling every 10 years or less; for count period 2014, 83 eagles, in 2003, 40, in 1993, 21, and in 1983, 7.
Reference made in last week's column to crabapple seedling prices was unfortunately outdated. Also, three species of shrub favored by wild turkeys in winter are unavailable for sale or importation into New Hampshire. The barberry, multiflora rose, and bittersweet are considered invasive species. Phone numbers were included for several large nurseries; and information may also be obtained from the NH Forest Nursery, Boscawen.
Stacey Cole's address is 529 W. Swanzey Road, Swanzey 03446.