Breeding Populations of the Osprey in Lower California
1947; Oxford University Press; Volume: 49; Issue: 4 Linguagem: Inglês
10.2307/1364109
ISSN1938-5129
Autores Tópico(s)Ecology and Vegetation Dynamics Studies
ResumoThe American Osprey (Pan&n h&a&u carolinensis), according to Grinnell (1928: 113)) has long been considered a common resident along ' the Pacific coast and adjacent islands of Lower California.However, after spending April and May of 1936 afield in this area, the writer thinks it worthwhile at this time to bring our knowledge of the status of certain populations of the Osprey in this area up to date and to compare their present status with that of the recorded past.The period beginning with the turn of the century and extending to the present day has brought a marked reduction in the breeding population of the Osprey along the coast of southern California.This decrease in the breeding Ospreys has apparently also been taking place somewhat more slowly at certain points along the coast of Lower California.My data were gathered in the course of a cruise aboard the twenty-three foot auxiliary sloop Seven Seas in company with Mr. M. W. Williams.An attempt was made to cover parts of the west coast and a number of the adjacent islands of the northern portion of Lower California (see fig. 25).The area covered is bound&l on the north by the international boundary and on the south by Natividad Island.The latter is at latitude 27" 53' , slightly south of Cedros Island.Since all points lie either close to or on the west coast of Lower California, latitude only is given in locating them.The coast and islands of this portion of Lower California are characterized by rocky shores devoid of any fresh water supply and are frequently whipped by strong sea winds and resulting rough seas.Its only human inhabitants are scattered fishermen.It is an area usually omitted by those who wish to cruise in southern waters.Since previous writers have been thorough in their descriptions of the areas covered by this paper, little such descriptive information is included.The areas will be considered in order from north to south as they were visited.The first area, which in past times maintained a considerable Osprey population, is the rocky coast line adjacent to Ensenada.This includes the Todos Santos Islands.A landing was not made on the Todos Santos Islands.However, on April 2, and again on May 26, a close approach to them was made as well as to the rocks adjacent to Banda Point.No Osprey was seen.The only indication that Ospreys had been present in the area was what appeared to be a bulky nest of sticks on one of the larger rocks near the west shore of Banda Point.Although the time spent in the immediate vicinity of this nest was less than half a day, we lay at anchor nearby in the shelter of Banda Point for four days during a storm.It is interesting to note that in the summer of 1897 Kaeding (1905: 134) reported the Osprey as " . . .common on . . .Todos Santos . . ..yHowell (1912: 189) states that between April 15 and 20, 1910, several dozen old nests were seen near the islands and along the adjacent coast.However, only one pair of Ospreys.wasobserved.Van Denburgh ( 1924: 70) writes that he saw no Ospreys at the Todos Santos Islands when he visited them from May 24 to 30, 1923.He cites Kaeding as having taken a set of eggs there on March 10, 1897.Judging from the foregoing references the breeding population of Ospreys became much reduced between 1897 and 1910 and may have been entirely gone by 1923.Bancroft (19273: 194)) however, states that the Ospreys " . . .are abundant from Ensenada Bay to Scammons . . .."As this statement does not appear to be based on any specific observation, it should perhaps be ignored in view of other observations.I was on the lookout for Ospreys and expected that if any were in the area during the storm referred
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