Dataset Identification:
Resource Abstract:
- description: Lake Umbagog s Common Loon population has been monitored for 24 years. In 1993, the level of resolution of reproductive
performance was improved with the initiation of a program to uniquely color-mark individuals. Since 1976, the number of territorial
pairs has increased from 9 to 28 and reflects a similar increase in loon populations across New Hampshire. However, long-term
reproductive measures indicate two major concerns for loon conservation. First, the number of fledged young per territorial
pair has significantly declined in the past four years (0.28) and is well below the 24- year mean for Lake Umbagog (0.46).
Second, the discrepancy of reproductive measures between the north and south ends of the lake continue to widen. Observations
of marked individuals indicate site fidelity (84.5%) and survivorship (93.5%) are above or near average levels of other breeding
populations, thereby indicating density dependent factors are not the sole source of impacts for current loon demographics.
Water level manipulation and methylmercury availability were investigated and found to be potential sources of impact on healthy
breeding populations. Although mean mercury exposure to loons and their prey fish on Lake Umbagog are moderate compared to
watershed-wide levels, certain areas of the lake such as the southern end and the Magalloway River carry Hg loads potentially
damaging at the molecular, organism, and population levels. The changes in water levels have a dual effect on the viability
of Lake Umbagog s loon population. Although positive steps have been taken to minimize waterlevel impacts on loon nesting
success, 13% of their nests in the past seven years failed due to floodings and strandings. Changes in water levels, especially
during the summer, are also known to exaggerate methylmercury production and create artificially high levels.; abstract: Lake
Umbagog s Common Loon population has been monitored for 24 years. In 1993, the level of resolution of reproductive performance
was improved with the initiation of a program to uniquely color-mark individuals. Since 1976, the number of territorial pairs
has increased from 9 to 28 and reflects a similar increase in loon populations across New Hampshire. However, long-term reproductive
measures indicate two major concerns for loon conservation. First, the number of fledged young per territorial pair has significantly
declined in the past four years (0.28) and is well below the 24- year mean for Lake Umbagog (0.46). Second, the discrepancy
of reproductive measures between the north and south ends of the lake continue to widen. Observations of marked individuals
indicate site fidelity (84.5%) and survivorship (93.5%) are above or near average levels of other breeding populations, thereby
indicating density dependent factors are not the sole source of impacts for current loon demographics. Water level manipulation
and methylmercury availability were investigated and found to be potential sources of impact on healthy breeding populations.
Although mean mercury exposure to loons and their prey fish on Lake Umbagog are moderate compared to watershed-wide levels,
certain areas of the lake such as the southern end and the Magalloway River carry Hg loads potentially damaging at the molecular,
organism, and population levels. The changes in water levels have a dual effect on the viability of Lake Umbagog s loon population.
Although positive steps have been taken to minimize waterlevel impacts on loon nesting success, 13% of their nests in the
past seven years failed due to floodings and strandings. Changes in water levels, especially during the summer, are also known
to exaggerate methylmercury production and create artificially high levels.
Citation
- Title Aspects of Hydrological Impacts on the Common Loon at Lake Umbagog, 1976-99.
-
- creation Date
2018-05-20T19:45:16.229172
Resource language:
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Metadata data stamp:
2018-08-07T01:08:14Z
Resource Maintenance Information
- maintenance or update frequency:
- 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 2018-08-07T01:08:14Z
Metadata contact
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pointOfContact
- organisation Name
CINERGI Metadata catalog
-
- Contact information
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-
- Address
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- electronic Mail Address cinergi@sdsc.edu
Metadata language
eng
Metadata character set encoding:
utf8
Metadata standard for this record:
ISO 19139 Geographic Information - Metadata - Implementation Specification
standard version:
2007
Metadata record identifier:
urn:dciso:metadataabout:dfc1c482-cd55-4c7e-bf7c-8b24aaabc766
Metadata record format is ISO19139 XML (MD_Metadata)