Can Saving One Bird Make
by Stephanie Streeter
from DVRC Journal Fall/Winter 96
The goal of DVRC and other raptor rehabilitation facilities is to return injured birds to the wild, and return them we do, but do these individual birds make a difference? Do they have any impact on their species' population, the environment they are released into, or the prey they most often hunt? For common raptors like the red-tailed hawk or the great horned owl the answer from a scientific prospective is clearly no. Which is not to say that treating and returning injured birds to the wild should not be undertaken.
And though it is true that most injured raptors second chance at life does not scientifically have a calculable effect, it is also true that returning just one bird of prey of an endangered species to the wild can have a tremendous impact. The greatest effect is seen in small populations such as Pennsylvania's recovering ospreys.
The osprey, sometimes called the fish hawk, is a truly unique bird of prey. In fact it is so unique that it is in a scientific class (Pandion) of its own. Unlike the bald eagle that routinely eats waterfowl and carrion along with fish, the osprey eats almost exclusively fish (ospreys have been documented catching small birds and mammals). The high-diving fish hawk has evolved many notable adaptations for catching its prey; among them, toes that are equal in length, with the outer toes being reversible (a trait shared with owls), so that fish can be firmly grasped with two toes forward and two in back. Ospreys have a further refinement to help them hold on to slippery prey, small raised rough bumps that feel like sandpaper along the bottoms of their feet and toes called spicules. Anyone who works with ospreys can tell you that they have a distinctive, though not unpleasant odor. Without opening a box containing an injured hawk, I know it is an osprey by smell alone. This characteristic scent is not, as might be expected, from the many fish the bird eats, but, from the heavy oil it secretes to keep its plumage superbly water resistant.
Ospreys have to be water resistant because this is the only bird of prey that routinely dives into the water, always feet first, to catch its prey. The bald eagle does not submerge itself like the osprey when hunting; instead, it plucks fish out of the water that are swimming close to the surface. After being submerged, an osprey can easily power itself out of the water with its incredibly agile wings, something the more robust, lumbering bald eagle has difficulty doing.
As Pennsylvania's osprey population increases, so too do the number of ospreys treated at DVRC. This summer, the center admitted two ospreys. One, a juvenile hatched this year, was electrocuted (for more on this bird's story see the "Director's Letter" in the Fall/Winter 96 issue of the DVRC Journal). The other, an adult, was found in a parking lot of a car dealer not far from a private fish hatchery in Monroe County. The bird was in shock when the Conservation Officer arrived. It could not stand because one leg was broken and the other was lacerated to the bone. In spite of surgery and intensive post-operative care the osprey did not survive. The cause of the bird's death was injuries from gunshot.
If this osprey had survived and been returned to the wild, would it have made a difference? Most likely, yes. But, in order to understand just why the rehabilitation and release of a single bird can have such a lasting impact, it is necessary to have some knowledge of the species status, both past and present. In the case of the osprey, its numbers suffered a catastrophic decline after World War II due mostly to the pesticide DDT which played havoc with the birds' reproductive cycle. By 1980, when Dr. Larry Rymon of East Stroudsburg College (now East Stroudsburg University) began the first osprey reintroduction project in the world, there were no longer any fish hawks living and breeding in Pennsylvania. Between 1980 and 1986, Dr. Rymon reintroduced 110 ospreys into the state. By 1988, Pennsylvania could boast of 12 active osprey nests.
Although the population of these remarkable birds is now firmly established and growing (as of 1996 Pennsylvania has 30 active nests) their numbers are still small enough that one bird being returned to the wild can indeed make a difference. Proof of this is in the well-documented story of a male osprey brought to DVRC on September 6, 1993 for treatment of a deep puncture wound to the upper chest. When this bird crossed the threshold of the clinic, there were only 10 nesting pairs of ospreys in northeastern Pennsylvania. Of those, the 11 year-old injured male and his mate were the oldest and most successful breeders in the state.
Getting this bird back to his mate in the wild, we felt, was essential. But, we were working against a deadline. Ospreys migrate each fall to Central or South America racking up impressive flying distances of 3,000 miles round trip. Because they travel such great spans, ospreys migrate relatively early each fall. By mid to late October, most ospreys have left the Northeast. Our challenge was, therefore, one of healing and flight conditioning played against the clock.
Fate smiled kindly on us with this bird and by early October, following daily medical attention, the deep wound had healed. Jan began flight conditioning as soon as the bird was well and by October 6, 1993 the fish hawk that had captured all our hearts was set free by the man who 11 years earlier had placed him in a hack box on Pocono Lake. TV camera people and newspaper photographers trained their lenses on the newly freed bird to record his release and, hopefully, the beginning of his lengthy migration.
We had done our job, but would have to wait until spring to find out if we had done it well enough. On April 13, 1994, we received a note from DVRC member Jean Littlefield telling us that the injured bird she had found and we had cared for was back at his nest and breeding with his mate. Jean admitted, she too had been anxious about the bird's return. In her note, she said the pair usually returned to its nest together, but that year the female arrived a full two weeks before the male. While the female osprey waited for her mate, she successfully defended their territory against two other ospreys. Their subsequent nesting produced three young.
In the spring of 1995 the pair returned to Pocono Lake and successfully raised three chicks. The spring of 1996 saw the ospreys back at their nest site caring for young but, tragically, these chicks did not fledge. According to Jean Littlefield, the nest slid off the nesting platform drowning the young which could not yet fly. The platform, which was built on a pole erected in the lake, had been leaning slightly for the past few years. Perhaps all of the snow from last winter weakened the platform enough so that the added weight of the growing chicks caused it to dump the nest into the water. The injured male and his mate did remain at the lake for most of the summer. Hopefully, Pennsylvania's oldest and most prolific pair of ospreys will return next year to raise young on a newly repaired and reinforced nest platform.
1998 UPDATE TO STORY: The following winter, volunteers (of what we don't know) repaired the nest to prepare it for the pair's return, hoping for a more successful season. It worked. It's not Spring at DVRC until we receive a note in the mail from the couple who initially rescued the osprey and who continue to monitor the nesting. As of the 1998 breeding season, they have been nesting successfully since the unfortunate loss of the drowned young.
So, can returning one bird to the wild really make a difference? In this case, the numbers tell the story. Since the male osprey's injury in 1993, he and his mate produced nine young, six of which fledged and added their numbers to Pennsylvania's growing osprey population. And while their last nesting did end in tragedy, the summer was not a failure because two other nests on Pocono Lake established, in part, by the pair's progeny successfully hatched and fledged young.
In the end though, perhaps cold, sterile numbers cannot adequately measure the impact of a bird's return to the wild. There is no number or graph that can record the visceral thrill of seeing a once absent osprey plunging feet first into the icy calm of a lake only to emerge seconds later with a fish triumphantly grasped in its talons. Quite simply, our hearts tell us this bird has made a difference, and that is enough.
Want to know more about the Osprey? Go to A Builder, A Collector, ... to learn about the Osprey's nest building habits.