Sherri L. Miller

Regional population monitoring of the marbled murrelet: field and analytical methods.

The marbled murrelet (Brachyramphus marmoratus) ranges from Alaska to California and is listed under the Endangered Species Act as a threatened species in Washington, Oregon, and California. Marbled murrelet recovery depends, in large part, on conservation and restoration of breeding habitat on federally managed lands. A major objective of the Northwest Forest Plan (the Plan) is to conserve and restore nesting habitat that will sustain a viable marbled murrelet population. Under the Plan, monitoring is an essential component and is designed to help managers understand the degree to which the Plan is meeting this objective. This report describes methods used to assess the status and trend of marbled murrelet populations under the Plan.

Northwest Forest Plan—the first 10 years (1994-2003): status and trends of populations and nesting habitat for the marbled murrelet.

The Northwest Forest Plan (the Plan) is a large-scale ecosystem management plan for federal land in the Pacific Northwest. Marbled murrelet (Brachyramphus marmoratus) populations and habitat were monitored to evaluate effectiveness of the Plan. The chapters in this volume summarize information on marbled murrelet ecology and present the monitoring results for marbled murrelets over the first 10 years of the Plan, 1994 to 2003. The marbled murrelet was federally listed in 1992 as threatened in Washington, Oregon, and California. The Plan identified the marbled murrelet as a major objective in the Plan design and hence the status of the murrelet is a key indicator of the Plan’s potential success. Effectiveness monitoring for the marbled murrelet has two facets: (1) assess population trends at sea by using a unified sampling design and standardized survey methods, and (2) establish a credible estimate of baseline nesting-habitat data by modeling habitat relations, and use the baseline to track habitat changes over time. Our primary monitoring objective was to determine the status and trends of marbled murrelet populations and nesting habitat in the Plan area.

Morphometric variation in Tundra Swans: relationships among sex and age classes

Variation in 36 morphometric variables among 82 Tundra Swans (Cygnus columbianus) wintering in Humboldt County, California, was evaluated; 15 variables were analyzed in detail to identify patterns of morphometric variation and differences among sex-age classes. Adult males were the largest class, and males had a significant positive covariation between wing length and other external and internal morphological features. There was no such covariation among females. When 15 morphological variables were evaluated with a principal components analysis, seven components accounted for 74% of the observed variation. Only the first component, associated with external body size and heart weight, was aligned with sex and age differences. There was some sex-age variation associated with viscera weights, and to a lesser extent with tarsus size in relation to bill length. There was little sex-age variation among most bill measures, body fat measures, or spleen weight. Based on a discriminant function analysis, five of the 15 variables discriminated the morphologies of the sex-age groups. Our data suggest that sexual dimorphism is minor in immatures, but pronounced in adults. This increase of dimorphism with age occurred for most external and internal characters, but was not apparent for bill dimensions. We believe that Tundra Swans can be classified into three distinct-roups on the basis of internal and external morphological features: (1) adult males have a relatively large body size but are similar in viscera weight and foot length to immature swans; (2) adult females are intermediate in body size, small in viscera weight, and smaller in foot length than adult and immature males; and (3) immature swans are relatively small-bodied, but similar in viscera weights and foot length measures to adult males.

Probable drowning of tundra swans on the northern coast of California.

Incidents of suspected drowning have been reported for ducks in North America (Wooten, 1954, J. Wildl. Manage. 18: 140141; Denson, 1961, Waterfowl populations and a comparison of hunting metho d s on south Humboldt Bay, California in 1959 and 1960, M.S. Thesis, Humboldt State University, Arcata, California, pp. 108-109). There are only a few reports of drowning of swans in North America (Fleming, 1908, Auk 25: 306-309; Fleming, 1912, Auk 29: 445-448). This is a report of the probable drowning of tundra swans (Cygnus columbianus) on the northern coast of California. On 7 January 1984, dead swans were reported at the mouth of the Eel River, Humboldt County, California. Aerial observations confirmed the presence of approximately 135 swan carcasses in the sand on the north and south spits of the river mouth. Approximately 750 live swans, in six groups, were seen grazing in nearby agricultural fields. Based on the U.S. Fish and Wildlife Service waterfowl survey of the Eel River delta on 3 January 1984, an estimated 14,200 ducks (composed of 11 species), 975 coots (Fulica americana) and 861 swans were present on the area. However, during the aerial observations of swan mortality over the Eel River and a surrounding 65 km2 area, no dead birds other than the 135 swans were seen on the coast, in the river, or in adjacent fields. On 10 January, 95 swan carcasses were collected from the north spit beach by staff of the U S . Fish and Wildlife Service. Each

RECOVERY OF PASTEURELLA MULTOCIDA FROM EXPERIMENTALLY-EXPOSED FRESHWATER SNAILS

We determined how long Pasteurella multocida could survive in experimentally-exposed freshwater snails. Physa virginea were collected from the Sacramento National Wildlife Refuge, Glenn County, California (USA), an enzootic site for avian cholera. Exposure to water containing up to 107 P. multocida per ml did not produce observable changes or mortality in snails. A minimum of 84 P. multocida per snail was necessary for detection among the normal snail bacterial flora. When snails were exposed to P. multocida in vials containing 107 bacteria per ml, P. multocida was detected for up to 72 hours in snails. When uninoculated snails were placed in aquaria containing 106 P. multocida per ml, P. multocida was not detected within the snails; further, P. multocida was detected in the water for only 24 hours at this level. Based on these results, we propose that P. virginea is not an effective reservoir for P. multocida.