Cheryl B. Schultz

EDGE‐MEDIATED DISPERSAL BEHAVIOR IN A PRAIRIE BUTTERFLY

Animal responses to habitat boundaries will influence the effects of habitat fragmentation on population dynamics. Although this is an intuitive and often observed animal behavior, the influences of habitat boundaries have rarely been quantified in the field or considered in theoretical models of large scale processes. We quantified movement behavior of the Fenders blue butterfly (Icaricia icarioides fenderi) as a function of distance from host-plant patches. We measured the butterflys tendency to move toward habitat patches (bias) and their tendency to continue to move in the direction they were already going (correlation). We found that butterflies significantly modify their behavior within 10–22 m from the habitat boundary. We used these data to predict large scale patterns of residence time as a function of patch size, using three dispersal models: homogeneous response to habitat, heterogeneous response to habitat, and heterogeneous response to habitat with edge-mediated behavior. We simulated movement for males and females in eight patch sizes (0.1–8 ha) and asked how residence time varies among the models. We found that adding edge-mediated behavior significantly increases the residence of Fenders blue butterflies in their natal patch. Only the model with edge-mediated behavior for females was consistent with independent mark–release–recapture (MRR) estimates of residence time; other models dramatically underestimated residence times, relative to MRR data.

Landscape Restoration: Moving from Generalities to Methodologies

Abstract Large-scale, landscape-level restoration actions are widely implemented but receive little attention from academic ecologists. We review the methods used to assess the role of these processes in past studies, and suggest ways to use past and ongoing restoration activities to increase our understanding of large-scale processes and improve restoration projects. To make better use of past restoration, we recommend the use of a number of alternative analytical approaches that have become widely applied in conservation biology and wildlife management but have yet to be adopted in restoration ecology.

Testing Simple Indices of Habitat Proximity

Simple measures of habitat proximity made primarily on the basis of land cover are widely used in the ecological literature to infer habitat connectivity, or the potential for animal movement among resource patches. However, such indices rarely have been tested against observations of animal movement or against more detailed biological models. We developed a priori expectations as to the types of study systems and organisms for which various habitat proximity indices would be best suited. We then used data from three study systems and four species to test which, if any, of the indices were good predictors of population‐level responses. Our a priori expectations about index performance were not upheld. The indices that consider both habitat area and distance from the focal patch were highly correlated with each other, suggesting that they do index similar quantities. However, none of the indices performed well in predicting population response variables. The results suggest that the pattern of habitat cover alone may be insufficient to predict the process of animal movement.

Nectar and hostplant scarcity limit populations of an endangered Oregon butterfly

Abstract As grassland habitats become degraded, declines in juvenile and adult food resources may limit populations of rare insects. Fenders blue butterfly (Icaricia icarioides fenderi), a species proposed for listing as endangered under the US Endangered Species Act, survives in remnants of upland prairie in western Oregon. We investigated the effects of limited larval hostplants and adult nectar sources on butterfly population size at four sites that encompass a range of resource densities. We used coarse and detailed estimates of resource abundance to test hypotheses relating resource quantity to population size. Coarse estimates of resources (percent cover of hostplant and density of nectar flowers) suggest that butterfly population size is not associated with resource availability. However, more detailed estimates of resources (density of hostplant leaves and quantity of nectar from native nectar sources) suggest that butterfly population size is strongly associated with resource availability. The results of this study suggest that restoring degraded habitat by augmenting adult and larval resources will play an important role in managing populations of this rare butterfly.

Age and reproduction in Savannah sparrows and tree swallows

1. Compared to older females, 1-year-old Savannah sparrows (Passerculus sandwichensis) and tree swallows (Tachycineta bicolor), studied over seven breeding seasons on Kent Island, New Brunswick, Canada, laid eggs later in the season, had smaller clutches, and produced fewer surviving offspring. 2. To determine why young birds have lower reproductive success than older birds, we induced birds of different ages to replace clutches under the same conditions by removing clutches in an experiment simulating nest predation. 3. In both species, yearlings produced eggs similar in size to those of older demales, by they laid fewer eggs per clutch in both first an replacement clutches than older birds

Restoration, Reintroduction, and captive Propagation for at-risk Butterflies: A review of British and American Conservation Efforts

Populations of at-risk butterfly species are declining at an alarming rate. Conservation strategies emphasize a mix of restoration of butterfly habitat, captive propagation, and reintroduction of butterflies to repopulate sites at which populations have gone extinct and to augment declining populations. We review the use of these strategies to conserve butterflies for 25 British species with Species Action Plans and 25 American species listed as Endangered, Threatened, or Candidate under the US Endangered Species Act and found in the continental US. Based on a broad review of published and unpublished literature and 47 interviews with agency staff, we find that the majority of species require active restoration (n = 47 of 50) and that most species receive restoration enhancements (n = 45), but only for a few species are ecological responses to this management monitored (n = 15). In addition, we find that most conservation strategies recommend reintroduction (n = 34) and it has been attempted for 21 Britis...

Conservation of Prairie-Oak Butterflies in Oregon, Washington, and British Columbia

Abstract Prairie-oak butterfly species in the Willamette Valley-Puget Trough-Georgia Basin (WPG) ecosystem have declined dramatically due to widespread habitat degradation and loss of prairie-oak ecosystems in the region. Conservation of prairie-oak butterflies offers unique opportunities and special challenges. Here we provide an overview of butterfly conservation in WPG prairies. We begin with a review of the status of at-risk butterfly species in the region, an introduction to five species that are the focus of current conservation efforts: Fenders blue (Icaricia icarioides fenderi), Taylors checkerspot (Euphydryas editha taylori), mardon skipper (Polites mardon), island marble (Euchloe ausonides insulanus), and Oregon silverspot (Speyeria zerene hippolyta), and a brief review of 10 additional at-risk butterfly species in the ecoregion. We follow with a discussion of three key threats (habitat loss and fragmentation, invasive species, and lack of appropriate disturbance) and four dominant management approaches (fire, herbicides, mowing, and habitat restoration). We discuss current challenges and emerging issues for these species, and focus on invasive species management, understanding basic biology, conserving multiple species, and adapting to climate change. We highlight several success stories from around the region. We conclude that butterfly biologists and land managers in the WPG are in a unique position to conserve the regions threatened prairie butterflies. Facilitating greater communication across the region through organizations such the Cascadia Prairie-Oak Partnership will assist in recovery of the WPGs threatened, endangered and at-risk butterfly species.

OLD MODELS EXPLAIN NEW OBSERVATIONS OF BUTTERFLY MOVEMENT AT PATCH EDGES

Understanding movement in heterogeneous environments is central to predicting how landscape changes affect animal populations. Several recent studies point out an intriguing and distinctive looping behavior by butterflies at habitat patch edges and hypothesize that this behavior requires a new framework for analyzing animal movement. We show that this looping behavior could be caused by a longstanding movement model, biased correlated random walk, with bias toward habitat patches. The ability of this longstanding model to explain recent observations reinforces the point that butterflies respond to habitat heterogeneity and do not move randomly through heterogeneous environments. We discuss the implications of different movement models for predicting butterfly responses to landscape change, and our rationale for retaining longstanding movement models, rather than developing new modeling frameworks for looping behavior at patch edges.

Long-Distance Movements by Fire Salamanders (Salamandra Infraimmaculata) and Implications for Habitat Fragmentation

Dispersal may be particularly important for the regional persistence of metapopulations that experience local extinctions. Some amphibian species are structured as metapopulations. Long-term persistence of these species should depend on natural connections between local subpopulations through dispersal. We explored movement distances of fire salamander adults (Salamandra infraimmaculata), a locally endangered species, on Mt. Carmel, northern Israel, and investigated the implications of movement for persistence of populations. During the breeding seasons (November-March) of 1999-2000 and 2002-2006, capture-recapture surveys were conducted around four breeding sites and along unpaved roads connecting them. Out of 300 adult salamander captures, 72 cases were recaptures. Most of the recaptures were in the same site as the initial capture. In eight cases (11%), however, salamanders were recaptured at least 400 m away from the first site. The maximum direct distances between capture-recapture sites (1100-1300 m...

Captive rearing of Puget blue butterflies (Icaricia icarioides blackmorei) and implications for conservation

The use of captive rearing to promote recovery of endangered butterflies has substantially increased over the last decade. These programs have the potential to play a significant role in butterfly population recovery, but the effects of captive conditions are poorly understood and rarely are traits of captive individuals assessed relative to traits in their founding populations. To develop rearing protocols and investigate possible effects of captive conditions, we reared Puget blue butterflies (Icaricia icarioides blackmorei), a subspecies closely related to the endangered Fender’s blue (I. i. fenderi) which is limited to Oregon, USA. We reared individuals from two wild populations in Washington, USA to investigate two approaches for egg collection (collect eggs in the wild vs. collect eggs from adult females which were brought to a greenhouse for oviposition) and three diapause environments (in indoor facilities at two independent locations vs. outdoors in enclosures). Survival from egg to adult was similar across all captive groups which survived past diapause and was less than 10%. Captive reared individuals were lighter and had smaller wings and shorter body lengths than their founding populations for both sites. Based on our findings, we recommend that rearing programs compare characteristics of reared individuals to individuals from the founding population to quantify possible effects of captive conditions, diapause individuals in natural environments, and for programs with survival rates similar to rates in the wild, consider alternatives to augment declining populations and reintroduce historic ones.