Steve Zack

ASSESSING THE DEVELOPMENT OF SHOREBIRD EGGS USING THE FLOTATION METHOD: SPECIES-SPECIFIC AND GENERALIZED REGRESSION MODELS

Abstract ABSTRACT We modeled the relationship between egg flotation and age of a developing embryo for 24 species of shorebirds. For 21 species, we used regression analyses to estimate hatching date by modeling egg angle and float height, measured as continuous variables, against embryo age. For eggs early in incubation, we used linear regression analyses to predict hatching date from logit-transformed egg angles only. For late incubation, we used multiple regression analyses to predict hatching date from both egg angles and float heights. In 30 of 36 cases, these equations estimated hatching date to within four days of the true hatching date for each species. After controlling for incubation duration and egg size, flotation patterns did not differ between shorebirds grouped by mass (≥100 g or <100 g) or taxonomy (Scolopacidae versus Charadriidae). Flotation progressed more rapidly in species in which both adults incubate the clutch versus species in which only one adult incubates the clutch, although this did not affect prediction accuracy. We also pooled all continuous data and created a generalized regression equation that can be applied to all shorebird species. For the remaining three species, we estimated hatching date using five float categories. Estimates of hatching date using categorical data were, overall, less accurate than those generated using continuous data (by 3%–5% of a given incubation period). Our equations were less accurate than results reported in similar studies; data collected by multiple observers and at multiple sites, as well as low sample sizes for some species, likely increased measurement error. To minimize flotation method prediction error, we recommend sampling in early incubation, collecting both egg angle and float height data in late incubation, and developing site- and species-specific regression models where possible.

Influence of human development and predators on nest survival of tundra birds, Arctic Coastal Plain, Alaska

Nest predation may influence population dynamics of birds on the Arctic Coastal Plain (ACP) of Alaska, USA. Anthropogenic development on the ACP is increasing, which may attract nest predators by providing artificial sources of food, perches, den sites, and nest sites. Enhanced populations or concentrations of human-subsidized predators may reduce nest survival for tundra-nesting birds. In this study, we tested the hypothesis that nest survival decreases in proximity to human infrastructure. We monitored 1257 nests of 13 shorebird species and 619 nests of four passerine species at seven sites on the ACP from 2002 to 2005. Study sites were chosen to represent a range of distances to infrastructure from 100 m to 80 km. We used Cox proportional hazards regression models to evaluate the effects of background (i.e., natural) factors and infrastructure on nest survival. We documented high spatial and temporal variability in nest survival, and site and year were both included in the best background model. We did not detect an effect of human infrastructure on nest survival for shorebirds as a group. In contrast, we found evidence that risk of predation for passerine nests increased within 5 km of infrastructure. This finding provides quantitative evidence of a relationship between infrastructure and nest survival for breeding passerines on the ACP. A posteriori finer-scale analyses (within oil field sites and individual species) suggested that Red and Red-necked Phalaropes combined (Phalaropus fulicarius, P. lobatus) had lower productivity closer to infrastructure and in areas with higher abundance of subsidized predators. However, we did not detect such a relationship between infrastructure and nest survival for Semipalmated and Pectoral Sandpipers (Calidris pusilla, C. melanotos), the two most abundant shorebirds. High variability in environmental conditions, nest survival, and predator numbers between sites and years may have contributed to these inconsistent results. We recommend targeted management actions to minimize anthropogenic effects and suggest new research needed on this issue as expanding development is planned for the ACP of Alaska. In particular, we recommend research on demography of key predators and their importance with respect to nest survival, and experimental studies that better address challenges posed by high natural variability.

Ecological effects of alternative fuel-reduction treatments: Highlights of the National Fire and Fire Surrogate study (FFS)

The 12-site National Fire and Fire Surrogate study (FFS) was a multivariate experiment that evaluated ecological consequences of alternative fuel-reduction treatments in seasonally dry forests of the US. Each site was a replicated experiment with a common design that compared an un-manipulated control, prescribed fire, mechanical and mechanical + fire treatments. Variables within the vegetation, fuelbed, forest floor and soil, bark beetles, tree diseases and wildlife were measured in 10-ha stands, and ecological response was compared among treatments at the site level, and across sites, to better understand the influence of differential site conditions. For most sites, treated stands were predicted to be more resilient to wildfire if it occurred shortly after treatment, but for most ecological variables, short-term response to treatments was subtle and transient. Strong site-specificity was observed in the response of most ecosystem variables, suggesting that practitioners employ adaptive management at the local scale. Because ecosystem components were tightly linked, adaptive management would need to include monitoring of a carefully chosen set of key variables. Mechanical treatments did not serve as surrogates for fire for most variables, suggesting that fire be maintained whenever possible. Restoration to pre-settlement conditions will require repeated treatments over time, with eastern forests requiring more frequent applications.

SMALL MAMMALS AND FOREST FUEL REDUCTION: NATIONAL-SCALE RESPONSES TO FIRE AND FIRE SURROGATES

Forest fuel reduction treatments are increasingly used by managers to reduce the risk of high-severity wildfire and to manage changes in the ecological function of forests. However, comparative ecological effects of the various types of treatments are poorly understood. We examined short-term patterns in small-mammal responses to mechanical thinning, prescribed-fire, and mechanical thinning/prescribed-fire combination treatments at eight different study areas across the United States as a part of the National Fire and Fire Surrogate (FFS) Project. Research questions included: (1) do treatments differ in their effect on small mammal densities and biomass? and (2) are effects of treatments consistent across study areas? We modeled taxa-specific densities and total small-mammal biomass as functions of treatment types and study area effects and ranked models based on an information-theoretic model selection criterion. Small-mammal taxa examined, including deer mice (Peromyscus maniculatus), yellow-pine chipmunks (Tamias amoenus), and golden-mantled ground squirrels (Spermophilus lateralis), as well as all Peromyscus and Tamias species, had top-ranked models with responses varying both by treatment type and study area. In each of these cases, the top-ranked model carried between 69% and 99% of the total weight in the model set, indicating strong support for the top-ranked models. However, the top-ranked model of total small-mammal biomass was a model with biomass varying only with treatment (i.e., treated vs. untreated), not by treatment type or study area; again, this model had strong support, with 75% of the total model weight. Individual species and taxa appear to have variable responses to fuel reduction treatment types in different areas; however, total small-mammal biomass appears generally to increase after any type of fuel reduction. These results suggest that there is substantial variability in taxa-specific responses to treatments and indicate that adaptive management policies may be necessary when applying fuel reduction treatments in areas where management of small-mammal populations is of interest. Adaptive management can be used by managers who are conducting fuel reduction treatments to reduce uncertainty as to which treatments are locally optimal for meeting objectives for the management of small-mammal populations.

THE ROLE OF FORAGING WOODPECKERS IN THE DECOMPOSITION OF PONDEROSA PINE SNAGS

Abstract We investigated the relationship between foraging woodpeckers and the decomposition of ponderosa pine (Pinus ponderosa) snags in the central and southern Cascades of Oregon and northern California. Our main objectives were (1) to compare the relative sapwood density of 4-year-old pine snags receiving varying levels of woodpecker foraging; and (2) to determine if woodpeckers were carriers of wood-inhabiting fungi. Snags used as foraging sites by woodpeckers had lower wood densities than snags that did not exhibit foraging sign. Additionally, wood-inhabiting fungi were recovered in significantly greater frequencies from the bills of woodpeckers than a comparison of non-cavity-nesting species. These results suggest that woodpeckers may contribute to the mechanical degradation of wood through foraging activities and the dispersal of a collection of fungi that likely participate in the process of decay for ponderosa pine snags. The complexity of these ecological interactions should be considered when planning snag management in coniferous forests. El Papel de Forrajeo de los Carpinteros en la Descomposición de Tocones de Pinus ponderosa Resumen. Investigamos la relación entre las actividades de forrajeo de los carpinteros y la descomposición de tocones de Pinus ponderosa en el centro y sur de las Cascades de Oregon y el norte de California. Nuestros objetivos principales fueron (1) comparar la densidad relativa de la albura de tocones de pino de 4 años de edad afectados por distintos niveles de forrajeo por parte de los carpinteros; y (2) determinar si los carpinteros transportaron hongos de la madera. Los tocones usados como sitios de forrajeo por los carpinteros tuvieron densidades de madera menores que los tocones que no presentaron señales de forrajeo. Adicionalmente, los hongos de la madera fueron encontrados con mayor frecuencia en los picos de los carpinteros que en especies que no nidifican en cavidades. Estos resultados sugieren que los carpinteros pueden contribuir a la degradación mecánica de la madera mediante las actividades de forrajeo y la dispersión de una variedad de hongos que probablemente participan en el proceso de descomposición de los tocones de P. ponderosa. La complejidad de estas interacciones ecológicas debería ser considerada a la hora de planear el manejo de los tocones en los bosques de coníferas.

Influence of beaver dam density on riparian areas and riparian birds in shrubsteppe of Wyoming

Abstract Through dam-building activity, beavers (Castor canadensis) play an important role in creating pond and wetland habitat for bird communities. Their impact may be intensified in semiarid landscapes and may increase with increasing dam density on a stream. Our objective was to examine relationships between dam density, riparian area characteristics, and the riparian bird community in a semiarid landscape. In 2002 and 2003 we surveyed riparian birds, riparian area characteristics, and the number of dams along 1.2-km sections of 11 streams in sagebrush steppe regions of Wyoming. We categorized the riparian bird community into 2 assemblages based on their affiliation with terrestrial or aquatic riparian habitats. Average width of the woody riparian zone, average riparian shrub height, and percent cover of emergent vegetation all had significant positive relationships with dam density, but percent cover of ponded water did not. Species richness and abundance of all riparian birds, and of the terrestrial assemblage, increased significantly with increasing woody riparian zone width. In contrast, richness and abundance of the aquatic assemblage were significantly positively influenced by cover of emergent vegetation and ponded water. When we accounted for riparian area characteristics, we found that total species richness, total abundance, and aquatic assemblage abundance were each positively correlated with dam density, suggesting that dam density is related to other riparian characteristics selected by birds. Our results suggest increasing dam-building activity may be important in creating favorable riparian conditions for a rich and abundant bird community in semiarid regions.

Abundance as a conservation value

A curious thing has happened to conservation biology. Many of us were inspired by our experiences with large groups of wild animals—be they in flocks, herds, or schools—and in many case drawn to conservation as a profession because of such experiences. And we have been increasingly educated through the work of historical ecologists on sliding baselines about how the abundance we encountered in our youth was nothing compared to the abundance of decades or centuries ago. Yet the discipline we embrace rarely considers abundance but instead has focused much of its attention and passion on loss, rarity, endangerment, minimum viable population sizes, and minimum viable conservation areas. Lost in this focus on the rare and endangered is attention to that phenomenon that inspired many of us—abundance. Abundance of species was a part of the experience of Europeans in many of the lands they settled. Not only have we had ample experience with abundance but also with the speed at which it can be lost: the collapse of American chestnut Castanea dentata that went from one of the most abundant trees in the north-eastern USA to extinct in a matter of decades. Or the passenger pigeon Ectopistes migratorius and North American bison Bison bison both of which collapsed from populations of tens of millions to either extinct or a few hundred animals. More recently we have come to understand the nature of the collapse of once incredibly abundant marine species, from oysters to sea turtles to cod and river herring (Jackson et al., 2011). These collapses are not just historical but have been occurring recently all around the world. The Madagascar radiated tortoise Astrochelys radiata was considered one of the world’s most abundant tortoises and but is now almost extinct (Hudson, 2011). A similar pattern has been seen in recent collapses of once abundant Asian vultures, caribou, forest elephants, sharks and the European horse chestnut Aesculapius hippocastanum. But despite evidence both from history and contemporary experience the conservation community has concentrated on species that are already endangered and has not seriously considered still abundant species to have a value for conservation. When we refer to abundance wemean not just the overall number of individuals but also the diversity of individuals within a group. Evidence shows that there is a great deal of variation between individuals within large populations and that this variation can be of significant behavioural and ecological import (Hutchinson, 2008; Redford & Feinsinger, 2001). Abundance is not only lots of the same but lots of differences as well. We suggest there are four major reasons for conservationists to care about the phenomenon of abundance. Firstly, wildlife in abundance, sometimes referred to as wildlife spectacles, helps inspire us and builds connections with the natural world. Numerous travel agencies andmedia organizations advertise the chance to experience or see wildlife in abundance, be it flamingos, coral reef fish, bald eagles, monarch butterflies or wildebeest. Many of these scenes are the ones that inspire conservationists and their supporters. Secondly, abundance is itself an ecological feature that maintains other species— including humans—and ecosystems (Gaston, 2011). Examples are numerous and reasonably well-documented, including forest elephants as seed dispersers, mound-building termites structuring communities, bees as pollinators, fish as sources of human food and conveyors of marine nutrients inland, and wolves indirectly as ecosystem engineers through trophic-level interactions. Thirdly, and increasingly well understood, abundant species provide many vital ecosystem services on which nature and we rely. These include water filtration by oysters (Ermgassen et al., 2013), nutrient transport by salmon and river herring (Gende et al., 2002; Hall et al., 2012), nutrient cycling and herbivory by wildebeest (Holdo et al., 2006) and ocean mixing by a variety of organisms from krill to fish (Kerr, 2006). Finally, it seems likely that it is easier in cost, and in management effort, to maintain abundance in wildlife populations than it is to keep once abundant and now rare species from extinction. Abundance is a buffer from perturbation whereas rarity is perpetual vulnerability. In the face of these strong reasons why has abundance not become an explicit conservation value? Strong arguments have been made in a set of important papers by KENT H. REDFORD Archipelago Consulting, Irvington NY 10533 USA. E-mail redfordkh@gmail.com

Range-wide conseRvation genetics of Buff-BReasted sandpipeRs (TRYNGITES SUBRUFICOLLIS)

ABSTRACT. Range-wide monitoring of shorebirds (Aves: Charadriiformes) suggests that many species are declining. For most species, it is unknown whether distinct population units exist, which makes management and conservation difficult. One shorebird of conservation concern, the Buff-breasted Sandpiper (Tryngites subruficollis), is a New World migrant that breeds at Arctic latitudes in North America and Russia and winters in southeastern South America. We conducted a molecular survey of samples representing each of three migratory regions (breeding, migration, and wintering) using nine polymorphic microsatellite loci and 1.5 kb of highly variable mitochondrial DNA (mtDNA) from the cytochrome b gene and mtDNA control region. We analyzed contemporary population structure, demographic trends, and phylogeographic patterns. Overall, microsatellite and mtDNA analyses revealed that Buff-breasted Sandpipers are panmictic both regionally and at a global scale, with no signal of a recent genetic bottleneck. The mtDNA analyses revealed a pattern of haplotype diversity consistent with an expansion from a single refugium (Tajimas D: -2.27, P < 0.01; Fus Fs: -30.6, P < 0.0001), after the height of the Wisconsinan glaciation (8,400–45,000 years before present). Overall, our molecular analyses suggest that Buff-breasted Sandpipers should be treated as a single conservation unit, and management efforts for this species should focus on limiting future declines to ensure that genetic viability is maintained.

Use of Standardized Visual Assessments of Riparian and Stream Condition to Manage Riparian Bird Habitat in Eastern Oregon

The importance of riparian vegetation to support stream function and provide riparian bird habitat in semiarid landscapes suggests that standardized assessment tools that include vegetation criteria to evaluate stream health could also be used to assess habitat conditions for riparian-dependent birds. We first evaluated the ability of two visual assessments of woody vegetation in the riparian zone (corridor width and height) to describe variation in the obligate riparian bird ensemble along 19 streams in eastern Oregon. Overall species richness and the abundances of three species all correlated significantly with both, but width was more important than height. We then examined the utility of the riparian zone criteria in three standardized and commonly used rapid visual riparian assessment protocols—the USDI BLM Proper Functioning Condition (PFC) assessment, the USDA NRCS Stream Visual Assessment Protocol (SVAP), and the U.S. EPA Habitat Assessment Field Data Sheet (HAFDS)—to assess potential riparian bird habitat. Based on the degree of correlation of bird species richness with assessment ratings, we found that PFC does not assess obligate riparian bird habitat condition, SVAP provides a coarse estimate, and HAFDS provides the best assessment. We recommend quantitative measures of woody vegetation for all assessments and that all protocols incorporate woody vegetation height. Given that rapid assessments may be the only source of information for thousands of kilometers of streams in the western United States, incorporating simple vegetation measurements is a critical step in evaluating the status of riparian bird habitat and provides a tool for tracking changes in vegetation condition resulting from management decisions.

Short-Term Effects of Fire and Fire-Surrogate Treatments on Avian Nest Survival: A National-Scale Analysis

We examined the initial response of avian nest success to mechanical thinning, prescribed fire, and thinning/ prescribed fire combination treatments, designed to reduce fuel loads, at study sites throughout the continental USA as part of the National Fire and Fire Surrogate (FFS) Project. We modeled the daily nest survival of ground-, shrub-, tree-, and snag-nesting bird species to test for effects of: (1) overall treatment (2) specific treatment category (i.e., burn, thin, thin/burn); (3) time since treatment; and (4) study site. Of the 7 species examined, only 2 had top models that included effects of the FFS treatments, the remainder had either constant survival rates, or rates that varied only by study site. The Eastern Towhee had top models that included effects of treatment and study site, while the Red-bellied Woodpecker had top models that included effects of treatment category, time since treatment, and study site. All estimates of treatment, treatment category, and study site were statistically weak with confidence intervals including zero. The lack of clear response patterns observed in this study is likely a consequence of the variability inherent across forest types and taxonomic groups we examined. Forest managers should use our results cautiously and also be encouraged to facilitate opportunities for studies of avian nest survival as a function of fire-surrogate treatments that are regional specific, encompass longer time frames and larger spatial scales.