Laird Henkel

Laird Henkel
California Department of Fish and Wildlife | DFG

MS Marine Science

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40
Publications
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330
Citations

Publications

Publications (40)
Article
Full-text available
We compiled findings from 15 years (1998-2012) of southern sea otter (Enhydra lutris nereis) necropsies, incorporating data from 560 animals. Sensitive diagnostic tests were used to detect biotoxins, bacteria, parasites and fungi. Methods to classify primary and contributing causes of death (COD) and sequelae utilized an updated understanding of he...
Article
Full-text available
Like many wildlife species of management concern, the western snowy plover Charadrius nivosus nivosus is the subject of intensive population monitoring. However, intensive monitoring of reproductive success for this shorebird is time consuming, financially costly, and potentially disruptive to the birds of interest. Due to these constraints, intens...
Article
Full-text available
Effectiveness of rehabilitating wildlife following oil spills has been controversial. Impacts include mortality or changes in behavior affecting health or reproduction. Immediately following a bunker fuel oil spill on San Francisco Bay, California, USA, a unique experiment was conducted to examine the movement and foraging behavior of Surf Scoters...
Article
From August through December 2015, beachcast bird survey programs reported increased deposition of common murres ( Uria aalge) on central and northern California beaches, but not on southern California beaches. Coastal wildlife rehabilitation centers received more than 1,000 live, stranded, and debilitated murres from Sonoma County to San Luis Obis...
Article
Full-text available
There is ongoing public debate about the best course of action to take when wildlife are affected by oil spills. Critics of wildlife rehabilitation suggest that the cleaning and release of oiled animals is a waste of resources focused on individual animals (not populations); thus, the most responsible course of action is to immediately euthanize af...
Article
International Oil Spill Conference Proceedings: May 2017, Vol. 2017, No. 1, pp. 605-617 A great deal of effort and resources is expended on the cleaning and rehabilitation of oiled wildlife, but the ultimate fate of these animals is often unknown. Post-release monitoring is essential for improving methodology and directing resources to those anima...
Technical Report
Full-text available
The Brown Pelican Mortality Working Group was formed in 2013 under Federal financial assistance from the U.S. Fish and Wildlife Service’s CDFA Program under the authority of the Endangered Species Act of 1973. This group aimed to establish a framework for tracking issues of concern regarding the health and viability of the California Brown Pelican...
Article
Full-text available
Sea otters (Enhydra lutris) have exceptionally high energetic requirements, which nearly double during lactation and pup care. Thus, females are extremely vulnerable to caloric insufficiency. Despite a number of compensatory strategies, the metabolic challenge of reproduction culminates in numerous maternal deaths annually. Massive depletion of ene...
Article
Full-text available
Species that undergo simultaneous flight-feather molt are susceptible to mortality during the flightless period. Remigial molt was examined in non-breeding Western Grebes (Aechmophorus occidentalis) and Clark's Grebes (A. clarkii) using beachcast carcasses from California to Washington to determine wrhere and when molt occurs and help identify regi...
Article
Captive-breeding and -rearing programs have been widely used for the conservation and recovery of imperiled species, and the success of such programs should be rigorously evaluated. In this study, we assessed the success of captive-rearing for a threatened shorebird, the snowy plover Charadrius nivosus, by comparing the survival and reproductive su...
Article
Population monitoring programs for threatened species are rarely designed to disentangle the effects of movements from changes in birth and death rates on estimated trends in abundance. Here, we illustrate how population and genetic monitoring can be integrated to understand the cause of large changes in the abundance of a threatened species of sea...
Article
Following the spill of bunker oil from the M/V Cosco Busan into San Francisco Bay, California on 7 November 2007, we evaluated the foraging characteristics, survival and movements of surf scoters (Melanitta perspicillata) that had been rehabilitated following formal rehabilitation protocols through the use of intracoelomic implants of radio transmi...
Article
Full-text available
The demographic consequences of oil spills or other mortality events for breeding seabird populations depend on the age and sex composition of the affected population. Differential wintering by sex and age classes occurs in many migratory bird species, and can have important conservation implications. We examined the age and sex ratios of Western G...
Article
Patterns of spatial and temporal co-occurrence or avoidance among different species of marine birds and mammals can provide insights into the degree to which these top predators compete for prey. I conducted at-sea surveys in nearshore waters of Monterey Bay, California, USA, and used a randomization technique to assess co-occurrence patterns of ma...
Article
Radio-telemetry was used to continuously monitor the at-sea activity of an adult Marbled Murrelet (Brachyramphus marmoratus) nesting in Santa Cruz County, California. From 05.39 h on 28 May 1997, to 05.14 h on 29 May 1997, the murrelet was followed by tracking teams at Año Nuevo Bay. Between 05.44 h and 20.19 h on 28 May, the bird engaged in eleven...
Article
We studied the seasonal abundance and spatial distribution of marine mammals in nearshore waters (<1 km from shore) of Monterey Bay, California, during 1999 and 2000. The most abundant mammal was California sea lion, Zalophus californianus, followed by harbor porpoise, Phocoena phocoena, sea otter, Enhydra lutris, and harbor seal, Phoca vitulina. S...
Article
In this study, the relationship between physical attributes of sandy beaches, levels of human disturbance, and shorebird occurrence was investigated. The linear density km-1 of shorebirds on 42 km of sandy beaches in Monterey Bay, California was documented from late autumn through spring, and the relationship of shorebird densities to two physical...
Technical Report
Full-text available
We conducted five at-sea surveys for Marbled Murrelets (Brachyramphus marmoratus) off central California during the 2007 breeding season; four surveys offshore of breeding habitat between Half Moon Bay and Santa Cruz, and one survey in northern Monterey Bay. Using distance sampling, we estimated the central California population at 367 (95% CL = 24...
Article
Full-text available
Breeding seabirds have been well studied but seabird ecology during the nonbreeding season is poorly understood because many species disperse far from breeding colonies to molt at sea. We characterized the timing of prebasic molt and postbreeding dispersal, described postbreeding dispersal movements, and estimated changes in body mass during molt f...
Technical Report
Full-text available
We conducted at-sea surveys for Marbled Murrelets (Brachyramphus marmoratus) in Conservation Zone 6 (central California) offshore of breeding habitat between Half Moon Bay and Santa Cruz in 2008. Using distance sampling estimation techniques, we estimated the central California population to be 122 (95% CL: 61-184) with surveys delineated from the...
Article
We compared density estimates for marine birds off central California from simultaneous aerial and boat-based surveys, with a special emphasis on Marbled Murrelets Brachyramphus marmoratus. We surveyed 44 eight-kilometer transects in nearshore waters of Monterey Bay, California, from December 2005 through March 2006. We found that density estimates...
Article
Information on the diet of the Marbled Murrelet, Brachyramphus marmoratus, in California is lacking. To assess availability of potential prey, we sampled small fishes at three locations in central California: Año Nuevo Bay, and two sites in northern Monterey Bay. These sites are used seasonally by Marbled Murrelets. Nearshore marine habitats were s...
Article
The distribution of marine birds relative to water clarity was examined in the nearshore waters of Monterey Bay, California. I conducted nine at-sea surveys in 1999 and 2000 and simultaneously recorded water clarity and the density of five taxa of marine birds. Among plunge-divers, Forster's Terns (Sterna forsteri) occurred more frequently than exp...
Article
Monterey Bay, California, is a site of regional significance for marine birds. I studied the seasonal abundance of marine birds within 1 km of shore in Mon- terey Bay during 1999 and 2000. Total bird abundance was greatest during spring and fall migration, whereas diversity was greatest during winter. Species assemblages were fairly consistent by s...
Technical Report
Full-text available
SUMMARY The Marbled Murrelet (Brachyramphus marmoratus) is a rare and threatened seabird that occurs in nearshore marine habitats along the west coast of North America. Previous at-sea surveys have been conducted for the species adjacent to breeding habitat (old-growth forest) from the Santa Cruz mountains (Santa Cruz County, California) north to A...
Article
Full-text available
Habitat use, diet and breeding biology of tufted puffins (Fratercula cirrhata) were studied in Prince William Sound, Alaska, during summer 1995. On Seal Island, 112 puffin burrows (71% active) were located. Of 95 accessible burrows, 49% were typical earthen burrows, whereas the remainder were atypical for the species (e.g., under tree roots). Hatch...

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