Dataset Identification:
Resource Abstract:
- description: The nesting population of greater sandhill cranes on Malheur National Wildlife Refuge, Oregon has declined from
236 pairs in 1971 to 181 pairs in 1986. Nesting studies conducted from 1966 to 1987 have repeatedly demonstrated that the
primary limiting factor for cranes nesting on Malheur Refuge is the predation of eggs by ravens, raccoons, and coyotes, and
the predations on prefledged chicks by coyotes. On 21 January 1986, Malheur Refuge staff assisted by U.S. Department of Agriculture
Animal and Plant Health Inspection Service) employees began controlling predators on approximately 27,000 acres (14%) of Malheur
Refuge. Recruitment of crane chicks in the predator control area (14.9%) was the highest ever recorded on the refuge. Because
of the highly successful results recorded in 1986, the predator control area was expanded in 1987 to include approximately
46% (85,000 acres) of the refuge. In 1987, 460 coyotes were removed by the following methods: aerial gunning(80%), calling
and shooting (8%), trapping and snares (7%), and denning (6%). An estimated 124 ravens were removed using 124 dozen chicken
eggs injected with DRC-1339 and an additional 13 ravens were shot. Sixteen raccoons were taken by the following methods: snare
3, shooting 3, live trap 3, and leg hold trap 7. Overall crane production was 43 chicks, less than the 50 recorded last year
but above the average annual production of 31. Recruitment was 10.6%, significantly higher than average (6.6%) but less than
the record of 14.9% recorded in last year's predator control area. Additional nesting studies of ducks showed a similar
pattern i.e., nesting success was well above long term averages but below the high levels recorded last year. The one notable
exception was Canada geese which had the highest nesting success ever recorded on the refuge. The primary factors believed
responsible for the diminished results in 1987 were: 1) much drier conditions in 1987 which reduced nesting habitat for cranes
and attracted more coyotes to the refuge from adjacent arid areas, 2) slightly higher coyote populations county-wide, 3) less
intense predator control efforts per acre in 1987 versus 1986, and 4) cool, wet weather in June that most likely increased
chick mortality. The objectives of the 1987 effort were to have a nesting success of 75%, fledging success 25%, and recruitment
15%. The actual outcome was 57%, 17.1%, and 10.6% respectively. All of these outcomes were well above long-term averages but
below objective levels. Based on these results, the 1987 season was judged a limited success. In comparing 1987 results with
long term averages for nesting success and chick mortality the data suggests that a minimum of 17-18 chicks (same as last
year) reached flight stage that would not have survived without predator control this year. It is recommended that control
efforts for 1988 be held the same as 1987 with an increased effort to be given to all control efforts, particularly during
April-flay.; abstract: The nesting population of greater sandhill cranes on Malheur National Wildlife Refuge, Oregon has declined
from 236 pairs in 1971 to 181 pairs in 1986. Nesting studies conducted from 1966 to 1987 have repeatedly demonstrated that
the primary limiting factor for cranes nesting on Malheur Refuge is the predation of eggs by ravens, raccoons, and coyotes,
and the predations on prefledged chicks by coyotes. On 21 January 1986, Malheur Refuge staff assisted by U.S. Department of
Agriculture Animal and Plant Health Inspection Service) employees began controlling predators on approximately 27,000 acres
(14%) of Malheur Refuge. Recruitment of crane chicks in the predator control area (14.9%) was the highest ever recorded on
the refuge. Because of the highly successful results recorded in 1986, the predator control area was expanded in 1987 to include
approximately 46% (85,000 acres) of the refuge. In 1987, 460 coyotes were removed by the following methods: aerial gunning(80%),
calling and shooting (8%), trapping and snares (7%), and denning (6%). An estimated 124 ravens were removed using 124 dozen
chicken eggs injected with DRC-1339 and an additional 13 ravens were shot. Sixteen raccoons were taken by the following methods:
snare 3, shooting 3, live trap 3, and leg hold trap 7. Overall crane production was 43 chicks, less than the 50 recorded last
year but above the average annual production of 31. Recruitment was 10.6%, significantly higher than average (6.6%) but less
than the record of 14.9% recorded in last year's predator control area. Additional nesting studies of ducks showed a
similar pattern i.e., nesting success was well above long term averages but below the high levels recorded last year. The
one notable exception was Canada geese which had the highest nesting success ever recorded on the refuge. The primary factors
believed responsible for the diminished results in 1987 were: 1) much drier conditions in 1987 which reduced nesting habitat
for cranes and attracted more coyotes to the refuge from adjacent arid areas, 2) slightly higher coyote populations county-wide,
3) less intense predator control efforts per acre in 1987 versus 1986, and 4) cool, wet weather in June that most likely increased
chick mortality. The objectives of the 1987 effort were to have a nesting success of 75%, fledging success 25%, and recruitment
15%. The actual outcome was 57%, 17.1%, and 10.6% respectively. All of these outcomes were well above long-term averages but
below objective levels. Based on these results, the 1987 season was judged a limited success. In comparing 1987 results with
long term averages for nesting success and chick mortality the data suggests that a minimum of 17-18 chicks (same as last
year) reached flight stage that would not have survived without predator control this year. It is recommended that control
efforts for 1988 be held the same as 1987 with an increased effort to be given to all control efforts, particularly during
April-flay.
Citation
- Title Progress report 1987: predator control to enhance the production of Greater Sandhill Cranes on Malheur National Wildlife Refuge.
-
- creation Date
2018-05-21T07:27:09.260295
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Metadata data stamp:
2018-08-06T23:42:55Z
Resource Maintenance Information
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- notes: This metadata record was generated by an xslt transformation from a dc metadata record; Transform by Stephen M. Richard, based
on a transform by Damian Ulbricht. Run on 2018-08-06T23:42:55Z
Metadata contact
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pointOfContact
- organisation Name
CINERGI Metadata catalog
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- electronic Mail Address cinergi@sdsc.edu
Metadata language
eng
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utf8
Metadata standard for this record:
ISO 19139 Geographic Information - Metadata - Implementation Specification
standard version:
2007
Metadata record identifier:
urn:dciso:metadataabout:2bba9c76-0ab5-4d1f-acef-419ca0e55fe4
Metadata record format is ISO19139 XML (MD_Metadata)