March 1997, Volume 30, Number 6

The Return of the Osprey March General Meeting Pee Wee Audubon NewAppointments Thank You Attention Birdathoners Madrone Turns Thirty Requesting an Address Change Pee Wee Report Observations MidweekWalkabout Results Beginners Bird Walks Audubon on the Air Birding's Economic Impact Audubon Day at Bouverie Bouverie Docent Training Audubon On Line Welcome New Members Help for Burrowing Owls Russian River Flood Dynamics

The Return of the Osprey by Betty Burridge THIS IS THE TIME OF YEAR when the Ospreys return to Sonoma County fromtheir migration, some having flown as far south as Chile. Their numbershere begin declining in November, and by the end of the year only a fewdie-hards are still plying the waters of the Russian River and along thecoast to Bodega Bay. Only two were reported on the December 19, 1996, WesternSonoma County Christmas Bird Count. But by March, we can again count onseeing them near our ocean shore, on fresh-water lakes, and along the RussianRiver and large streams. The Osprey, also known as the Sea Hawk or Fish Hawk, is especially rewardingto watch because of its large size and showy behavior. Even many non-birdersenjoy casual outings along the Russian River or at Spring Lake to observethem attending nest sites or actively diving for dinner. Care must be takento correctly identify these birds, though, for the white head can misleada beginner into erroneously "seeing" a "Bald Eagle." A courting pair in swift pursuit flight will soar, circle, and dodgewith rapid turns and quick swoops. From pair formation through egg-laying,the female is fed entirely by her mate. Two to four eggs are laid, and thesehatch asynchronously. Thus the oldest chick will probably be the biggestand strongest, and will be the most likely to survive. Chicks that hatchlater will thrive only if food is plentiful. A brood of three young reportedlyrequires six pounds of fish a day. (Paul Ehrlich et al. in The Birder'sHandbook.) The Osprey's nest is a huge conglomerate of sticks with a variety ofother items--grasses, vines, fishnet, etc.--for a lining. The tops of snags,or even man-made platforms are favored locations for these nests, whichmay be reused for many years. Two such platforms are visible from Highway1, on the Chanslor Ranch ponds just north of Bodega Bay. The Sonoma County Breeding Bird Atlas records ten study blockswith "confirmed" breeding records between 1986 and 1992; six with"probable" records and 23 with "possible" records. Multiplebreeding records within one Block are reflected as a single report of Ospreyin that study block, so the number of breeding pairs can be much greaterthan the number of blocks in which breeding is recorded. According to KenWilson, there is one spot along the Russian River west of Duncans Millsfrom which as many as 15 Osprey nests can be seen. Another good place towatch for them is from the overlook at the mouth of the river. By all appearances there is a healthy population of these birds locallyat this time. For several decades, however, the Osprey was a great causefor concern, after the population crashed in the 1950's. We know now thatexposure to DDT up until 1970, as well as encroachment on breeding groundsand shooting were responsible for the near demise of this raptor. The DDTban and conservation programs, including the successful use of nesting platforms,have helped its recovery. But as of 1994, the Osprey was still classifiedas a Species of Special Concern by the California Department of Fish andGame.

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