Paul R. Sievert

Survival of snowshoe hares at a geographic range boundary

The southern limit of snowshoe hare (Lepus americanus) distribution passes through central Wisconsin. Reproduction does not decline at this range boundary, hence lower survival must prevent addi- tional dispersal and colonization. During February 1982-January 1983 we monitored survival of radio- collared hares to test the hypothesis that predation is the major immediate cause of death and is heaviest on dispersers and individuals within habitats having little understory cover. We simulated dispersal by trans- planting snowshoes throughout the year onto study areas with and without good understory cover, inside and outside currently occupied range. A control cohort of residents (not transplanted) was also monitored year-round. Predators killed 87% of the 67 radio-collared hares that died. Decreased survival was strongly associated with hare movements and factors tending to increase movement: viz., dispersal, poor understory cover, presence of resident hares, and fragmented habitat. Survival was apparently enhanced by cover that concealed hares or obstructed predators. Poor physical condition and small body size were linked to increased rates of loss from predation. This study supports the view that predator-caused mortality determines the geographic limit of snowshoe hare distribution in Wisconsin, and losses are most markedly influenced by factors which induce movement. Dispersal beyond established home ranges may be relatively uncommon in these marginal populations due to heavy predation on individuals moving between patches of suitable habitat within relatively large home ranges. The high incidence of trap deaths among hares captured in bogs and the frequency of low bone marrow fat in live-trapped and predator-killed samples suggest that these snowshoes may compromise their access to an adequate food supply by seeking protection from predators in dense conifer cover.

Foraging destinations of three low-latitude albatross (Phoebastria) species

Satellite telemetry was used to identify the foraging distributions of three congeneric species of albatrosses that nest in the tropics/subtropics. Breeding waved albatrosses Phoebastria irrorata from the Galapagos Islands travelled to the productive upwelling near the Peruvian coast and nearby areas during the rearing period in 1996. Black-footed albatrosses P. nigripes and Laysan albatrosses P. immutabilis nesting in the Hawaiian Islands and tracked during the 1997-98 and 1998-99 breeding seasons also performed long foraging trips, to continental shelf areas of North America. In both years, breeding black-footed albatrosses made long trips to the west coast of North America (British Columbia to California). In 1997-98, breeding Laysan albatrosses travelled primarily to the north of the Hawaiian Islands and reached the waters of the Aleutian Islands and the Gulf of Alaska. In 1998-99, Laysan albatrosses had a complete breeding failure, and no long trips by breeders were tracked as a result. These three species mixed short and long trips during the chick-rearing period, but not the brooding period nor incubation period. Waved albatrosses made only long trips during the incubation period. Analysis of movement patterns showed that the core feeding areas during long trips were located over the continental shelves of North and South America. The data on foraging biology of these species have implications for assessing bycatch risk in commercial fisheries.

Wind, Waves, and Wing Loading: Morphological Specialization May Limit Range Expansion of Endangered Albatrosses

Among the varied adaptations for avian flight, the morphological traits allowing large-bodied albatrosses to capitalize on wind and wave energy for efficient long-distance flight are unparalleled. Consequently, the biogeographic distribution of most albatrosses is limited to the windiest oceanic regions on earth; however, exceptions exist. Species breeding in the North and Central Pacific Ocean (Phoebastria spp.) inhabit regions of lower wind speed and wave height than southern hemisphere genera, and have large intrageneric variation in body size and aerodynamic performance. Here, we test the hypothesis that regional wind and wave regimes explain observed differences in Phoebastria albatross morphology and we compare their aerodynamic performance to representatives from the other three genera of this globally distributed avian family. In the North and Central Pacific, two species (short-tailed P. albatrus and waved P. irrorata) are markedly larger, yet have the smallest breeding ranges near highly productive coastal upwelling systems. Short-tailed albatrosses, however, have 60% higher wing loading (weight per area of lift) compared to waved albatrosses. Indeed, calculated aerodynamic performance of waved albatrosses, the only tropical albatross species, is more similar to those of their smaller congeners (black-footed P. nigripes and Laysan P. immutabilis), which have relatively low wing loading and much larger foraging ranges that include central oceanic gyres of relatively low productivity. Globally, the aerodynamic performance of short-tailed and waved albatrosses are most anomalous for their body sizes, yet consistent with wind regimes within their breeding season foraging ranges. Our results are the first to integrate global wind and wave patterns with albatross aerodynamics, thereby identifying morphological specialization that may explain limited breeding ranges of two endangered albatross species. These results are further relevant to understanding past and potentially predicting future distributional limits of albatrosses globally, particularly with respect to climate change effects on basin-scale and regional wind fields.

Albatross species demonstrate regional differences in North Pacific marine contamination

Recent concern about negative effects on human health from elevated organochlorine and mercury concentrations in marine foods has highlighted the need to understand temporal and spatial patterns of marine pollution. Seabirds, long-lived pelagic predators with wide foraging ranges, can be used as indicators of regional contaminant patterns across large temporal and spatial scales. Here we evaluate contaminant levels, carbon and nitrogen stable isotope ratios, and satellite telemetry data from two sympatrically breeding North Pacific albatross species to demonstrate that (1) organochlorine and mercury contaminant levels are significantly higher in the California Current compared to levels in the high-latitude North Pacific and (2) levels of organochlorine contaminants in the North Pacific are increasing over time. Black-footed Albatrosses (Phoebastria nigripes) had 370-460% higher organochlorine (polychlorinated biphenyls [PCBs], dichlorodiphenyltrichloroethanes [DDTs]) and mercury body burdens than a closely related species, the Laysan Albatross (P. immutabilis), primarily due to regional segregation of their North Pacific foraging areas. PCBs (the sum of the individual PCB congeners analyzed) and DDE concentrations in both albatross species were 130-360% higher than concentrations measured a decade ago. Our results demonstrate dramatically high and increasing contaminant concentrations in the eastern North Pacific Ocean, a finding relevant to other marine predators, including humans.

Evaluating the Potential Effectiveness of Compensatory Mitigation Strategies for Marine Bycatch

Conservationists are continually seeking new strategies to reverse population declines and safeguard against species extinctions. Here we evaluate the potential efficacy of a recently proposed approach to offset a major anthropogenic threat to many marine vertebrates: incidental bycatch in commercial fisheries operations. This new approach, compensatory mitigation for marine bycatch (CMMB), is conceived as a way to replace or reduce mandated restrictions on fishing activities with compensatory activities (e.g., removal of introduced predators from islands) funded by levies placed on fishers. While efforts are underway to bring CMMB into policy discussions, to date there has not been a detailed evaluation of CMMBs potential as a conservation tool, and in particular, a list of necessary and sufficient criteria that CMMB must meet to be an effective conservation strategy. Here we present a list of criteria to assess CMMB that are tied to critical ecological aspects of the species targeted for conservation, the range of possible mitigation activities, and the multi-species impact of fisheries bycatch. We conclude that, overall, CMMB has little potential for benefit and a substantial potential for harm if implemented to solve most fisheries bycatch problems. In particular, CMMB is likely to be effective only when applied to short-lived and highly-fecund species (not the characteristics of most bycatch-impacted species) and to fisheries that take few non-target species, and especially few non-seabird species (not the characteristics of most fisheries). Thus, CMMB appears to have limited application and should only be implemented after rigorous appraisal on a case-specific basis; otherwise it has the potential to accelerate declines of marine species currently threatened by fisheries bycatch.

Movement patterns of Blanding's turtles (Emydoidea blandingii) in the suburban landscape of eastern Massachusetts

We studied Blandings turtle Emydoideablandingii home range and seasonal movement patterns at 10 sites in suburban eastern Massachusetts during 2001 and 2002. Radio telemetry was used to track 51 turtles (31 females and 20 males) and home range was estimated during 4 seasonal activity periods usingthe 95% fixed kernel estimator. Sex, year, and site were not found to affect home range size due to the large amount of variationbetween and within individuals. There were significant differences in home range length between activity periods, with longest movementsoccurring during the period of 15 April to 31 May as animals moved to ephemeral wetlands. Mean annual home range size for Blandings turtles was 22 ha, and mean home range length was 856 m. Animals frequently had annual home ranges that overlapped little from year to year, indicating that our calculations greatly underestimate the lifetime home range of an individual. Due to the large area needs of Blandings turtles, and the diversified ownership of lands in eastern Massachusetts, numerous stakeholders will need to be involved to effectively protect viable populations for the foreseeable future.

Microhabitat use by larvae and females of a rare barrens butterfly, frosted elfin (Callophrys irus)

The frosted elfin (Callophrys irus) is a localized and declining butterfly found in xeric open habitats maintained by disturbance. We described the effects of woody plant canopy cover, topography and host plant size and density on the quality of microhabitat of wild indigo (Baptisia tinctoria) host plants containing late instar frosted elfin larvae at four study sites in southeastern Massachusetts, United States. We also assessed whether females preferentially depositing eggs on host plants within specific microhabitats, therefore conferring greater survivorship to the larvae through the late-instar stage. We found that moderate amounts of canopy cover and large plant size characterized larvae-occupied host plants. In the absence of tree canopy cover, late instar larvae density remained low even when host plant density was high. However, females oviposited on wild indigo plants without regard to any of the vegetative or environmental variables we measured. These results indicate that canopy cover was an important characteristic of microhabitats containing late instar larvae, and late instar larvae occupancy was determined by suitable microhabitat conditions, and not female oviposition selection. Managing for canopy cover and microhabitat heterogeneity within relatively open habitats is recommended for the maintenance of frosted elfin populations.

Rhinos in the Parks: An Island-Wide Survey of the Last Wild Population of the Sumatran Rhinoceros.

In the 200 years since the Sumatran rhinoceros was first scientifically described (Fisher 1814), the range of the species has contracted from a broad region in Southeast Asia to three areas on the island of Sumatra and one in Kalimantan, Indonesia. Assessing population and spatial distribution of this very rare species is challenging because of their elusiveness and very low population number. Using an occupancy model with spatial dependency, we assessed the fraction of the total landscape occupied by Sumatran rhinos over a 30,345-km2 survey area and the effects of covariates in the areas where they are known to occur. In the Leuser Landscape (surveyed in 2007), the model averaging result of conditional occupancy estimate was ψ^(SE[ψ^])=0.151(0.109) or 2,371.47 km2, and the model averaging result of replicated level detection probability p^(SE[p^])=0.252(0.267); in Way Kambas National Park—2008: ψ^(SE[ψ^])=0.468(0.165) or 634.18 km2, and p^(SE[p^])=0.138(0.571); and in Bukit Barisan Selatan National Park—2010: ψ^(SE[ψ^])=0.322(0.049) or 819.67 km2, and p^(SE[p^])=0.365(0.42). In the Leuser Landscape, rhino occurrence was positively associated with primary dry land forest and rivers, and negatively associated with the presence of a road. In Way Kambas, occurrence was negatively associated with the presence of a road. In Bukit Barisan Selatan, occurrence was negatively associated with presence of primary dryland forest and rivers. Using the probabilities of site occupancy, we developed spatially explicit maps that can be used to outline intensive protection zones for in-situ conservation efforts, and provide a detailed assessment of conserving Sumatran rhinos in the wild. We summarize our core recommendation in four points: consolidate small population, strong protection, determine the percentage of breeding females, and recognize the cost of doing nothing. To reduce the probability of poaching, here we present only the randomized location of site level occupancy in our result while retaining the overall estimation of occupancy for a given area.

An evaluation of a weaning index for wild fishers (Pekania [Martes] pennanti) in California

Abstract Conservation concern for fishers (Pekania [Martes] pennanti) in the Pacific states has highlighted a need to develop cost-effective methods of monitoring reproduction in extant and reintroduced fisher populations. We evaluated the efficacy of nipple size as a predictive index of weaning success for females with known reproductive histories from 3 study areas in California. We captured and radiocollared 91 female fishers on 146 occasions between 2004 and 2011 and measured the width and height of all 4 nipples and quantified reproductive status via radiotelemetry. We classified each radiomarked female into 1 of 3 reproductive classes (nonbreeders, attempted breeders, and current breeders) based on our telemetry observations during the den season prior to capture. We used a modified random forests (RF) procedure to account for repeated measures of individual females sampled in multiple years. Our modified RF procedure correctly classified reproductive class for 130 (89%) and 131 (90%) of our 146 observations using raw and weighted vote totals, respectively. We calculated Cohens kappa of 0.80 and 0.81 using raw and weighted vote totals, respectively, indicating strong model performance. We conclude that nipple sizes of female fishers measured during a livetrapping effort can be used as a cost-effective index of the weaning rates of adult female fishers.

Correction: Rhinos in the Parks: An Island-Wide Survey of the Last Wild Population of the Sumatran Rhinoceros.

In the 200 years since the Sumatran rhinoceros was first scientifically described (Fisher 1814), the range of the species has contracted from a broad region in Southeast Asia to three areas on the island of Sumatra and one in Kalimantan, Indonesia. Assessing population and spatial distribution of this very rare species is challenging because of their elusiveness and very low population number. Using an occupancy model with spatial dependency, we assessed the fraction of the total landscape occupied by Sumatran rhinos over a 30,345-km 2 survey area and the effects of covariates in the areas where they are known to occur. In the Leuser Landscape (surveyed in 2007), the model averaging result of conditional occupancy