California Least Tern Breeding Survey 1992 Season

Metadata Updated: May 11, 2018

In 1992, approximately 2,106 pairs of the endangered California Least Tern (Sterna antillarum browni) nested at 38 sites along the coast of California, from the San Francisco Bay area in the north, south to the Mexican border. This 15% increase over 1991 breeding population size continues the trend since 1987 of continued growth of the population, and is directly attributable to the efforts of people working on behalf of recovery of the species. The statewide total of 2,106 pairs is the highest number recorded-since systematic monitoring began in 1973, and represents a greater than three-fold increase over the estimated 600 pairs of that year. The increase in the number of nesting sites over 1991 (34) and 1990 (30) reflects both the expansion of terns into new areas adjacent to already established sites, and the return of terns to areas used historically but not in the recent past. The increase hi the number of breeders was somewhat eclipsed by the much reduced statewide production of fledglings. The total of 1,362-1,448 fledglings produced in 1992 is lower than the numbers produced by 1,830 pairs in 1991 (1,729-1,839) and 1,706 pairs in 1990 (1,487-1,676). Low fledgling production per pair in 1992 (.6S-.69) was attributed to both predation and the deleterious effects of El Nino on food availability. Breeding failure and success was strikingly localized, and sites hit hardest by both predation and a shortage of food were located in the southern portion of the State (in San Diego County). Eight sites had relatively high fledgling production per pair (S>1); fledglings produced at four of those eight sites (NAS Alameda, Venice Beach, Seal Beach, Santa Margarita River North Beach) comprised 65% of the total produced statewide. Because an annual fledgling to pair ratio of less than 0.7 results in a decline in the size of the breeding population two years later, and past El Nino events have been shown to affect the population dynamics of terns over a protracted period, the combined effects of predation and low food availability on Least Tern reproductive success in 1992 are likely to hinder population growth for several years to come.

Access & Use Information

Restricted: This dataset can only be accessed or used under certain conditions. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.
The information resource is proprietary and/or copyrighted. Access to this information by the public is very limited. Please contact the associated Point of Contact regarding additional use constraints and requirements for obtaining the information.

Downloads & Resources

References

https://ecos.fws.gov/ServCat/Reference/Profile/933

References

https://ecos.fws.gov/ServCat/Reference/Profile/933

Dates

Metadata Created Date December 2, 2017
Metadata Updated Date May 11, 2018

Metadata Source

Harvested from DOI CKAN Harvest Source

Additional Metadata

Resource Type Dataset
Metadata Created Date December 2, 2017
Metadata Updated Date May 11, 2018
Publisher Fish and Wildlife Service
Unique Identifier FWS_ServCat_933
Maintainer
Brent Frakes
Maintainer Email
Public Access Level restricted public
Bureau Code "010:18"
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Metadata Catalog ID C:\Program Files (x86)\FWS\DataStore\Application\OpenData\FWS_ServCat_v1_1.json
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Data Quality true
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Harvest Object Id fbd79fa5-2dee-4122-b466-94700abefc70
Harvest Source Id 9364572a-43e2-4cb5-a0ee-589c8af0e137
Harvest Source Title FWS-servecat
Data First Published 1993-01-01
Homepage URL https://ecos.fws.gov/ServCat/Reference/Profile/933
Data Last Modified 1993-01-01
Program Code "010:094", "010:028"
Related Documents "https://ecos.fws.gov/ServCat/Reference/Profile/933"
Rights The information resource is proprietary and/or copyrighted. Access to this information by the public is very limited. Please contact the associated Point of Contact regarding additional use constraints and requirements for obtaining the information.
Source Datajson Identifier true
Source Hash 15c3e86e66a2b90c788aa4648ead96c4bdb42080
Source Schema Version 1.1
Temporal 1992-01-01/1992-12-31
Category "Published Report"

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