Conservation and Ecology of Birds II

Contributed Paper
ROOM: Rooms 18 – Cochiti and 30 – Taos Combined

1:10PM Adaptations of Tidal Marsh Sparrows to a Changing Environment
Alison R. Kocek; Jonathan B. Cohen; Bri Benvenuti; Alyssa Borowske; Chris S. Elphick; Christopher R. Field; Laura Garey; Thomas P. Hodgman; Adrienne I. Kovach; Rebecca A. Kern; Brian J. Olsen; Samuel G. Roberts; Katharine J. Ruskin; W. Gregory Shriver; Je
Tidal marshes are highly dynamic systems that support few terrestrial vertebrate species due to a combination of salinity, floristic simplicity, daily tidal inundation, and unpredictable flooding events. Those few species inhabiting tidal marshes are often uniquely adapted to this extreme environment. For endemic bird species, breeding failure most commonly occurs due to tidal inundation, leading to multiple nesting attempts per season. As global climate change induced sea level rise amplifies tides and intensifies flooding, predictions are grim for the continued persistence of species such as the saltmarsh sparrow (Ammodramus caudacutus), a tidal marsh obligate. However, in a recent study we found evidence of previously-undocumented variability in nest substrate use for saltmarsh sparrows which we investigated further. We examined nest placement, characteristics, and fates throughout the North Atlantic Coastal breeding range of saltmarsh and seaside sparrows (Ammodramus maritimus) to determine the potential for individual behavioral variation among multiple nest attempts. Saltmarsh sparrow females switched from one marsh elevation zone to another during a subsequent nest attempt especially following a nest loss due to flooding. They also built their following nest higher off the ground (χ2 test, α=0.05) except when losing a nest to depredation. Seaside sparrows appeared much more evolutionarily rigid in their nest building behaviors, nesting primarily in low elevation habitat and not changing their nest characteristics in any one direction following any initial nest fate. Our results provide evidence that saltmarsh sparrows display plasticity in the face of nest loss to flooding, with implications for habitat restoration and persistence time.
1:30PM Shorebird Nest Attendance in Response to Research Activities
Alicia K. Andes; Terry L. Shaffer; Mark H. Sherfy; Colin M. Dovichin; Susan N. Ellis-Felege
For federally listed species, such as piping plovers (Charadrius melodus; “plover”) and least terns (Sternula antillarum; “tern”), monitoring productivity is crucial to understand population dynamics and improve recovery plans. However, research activities may increase parental absences, causing prolonged exposure of unattended eggs to high sand temperatures, decreasing their survivability. Therefore, the objective of this study was to evaluate the influence of research activities on plover and tern nest attendance. We installed miniaturized surveillance cameras at 65 of 294 tern and 89 of 551 plover nests under observation on the Missouri River in North Dakota from 2013-2015. Video was reviewed to record start and stop times of incubation until the nests hatched or failed. Research activities were divided into types (nest searches, adult trapping, targeted searches and camera maintenance). We analyzed the proportion of time adults spent off of the nest one hour before, during and one hour after research activities. We found that the proportion of time off of the nest increased during all research activity types (estimate = 0.031, SE = 0.002) compared to before (estimate = 0.013, SE = 0.0024) and after periods when researchers were absent (estimate = 0.014, SE = 0.0024). Activities that focused more on locating and monitoring nests, such as nest searching (estimate = 0.019, SE = 0.0021), had less of an effect on nest attendance than camera checks (estimate = 0.065, SE = 0.0031) and targeted searches (estimate = 0.04, SE = 0.0036). The results from this study may be used to improve monitoring procedures for plovers and terns, as well as other shorebirds, in order to decrease potentially negative impacts from researcher activities.
1:50PM Secretive Marshbird Response to Wetland Plant Management in Western Minnesota
Nina Hill; David E. Andersen; Douglas H. Johnson; Tom Cooper
Many marshbird species are difficult to detect and existing avian survey methods (e.g., Breeding Bird Surveys) do not provide reliable estimates of population size or trends. It is unclear how these species have responded to historic widespread land-use conversion, nor to further changes instigated by invasive plants. To understand these relationships better, we used the Standardized North American Marsh Bird Monitoring Protocol to evaluate differences in 6 marshbird species’ abundance at wetlands associated with different vegetation management strategies in west-central and northwestern Minnesota. In our west-central Minnesota study area we established 17 survey routes to examine differences in marshbirds among 3 levels of management histories of prescribed burning and grazing during 2000-2014. In our northwestern Minnesota study area we surveyed 9 routes to assess marshbird use before and after herbicide application to control hybrid cattails (Typha x glauca). During 2015 and 2016 we conducted 467 surveys resulting in 621 observations of broadcast species in west-central Minnesota, and 238 surveys resulting in 726 observations in northwestern Minnesota. For each species we incorporated detection probability as a function of distance and available wetland area to adjust counts into bird density per point, and tested local and landscape level variables through the modeling process. Results show that some species of marshbirds were associated with high intensity level of vegetation management in our west-central Minnesota study area, indicating that a combination of fire and grazing influenced marshbird habitat quality. Our results provide reference information on distribution and relative abundance of marshbirds in western Minnesota landscapes that can inform vegetation management decisions.
2:10PM Ecological State Change of Saline Lakes on the Southern High Plains
David Haukos; Warren Conway; Destiney Hett; Brandon Weihs
ABSTRACT: Saline lakes on the Southern High Plains of Texas and New Mexico, represent unique ecological systems in a semi-arid landscape. The ~50 saline lakes are connected to the Ogallala Formation, which contains the Ogallala Aquifer. Each saline lake was represented by natural springs that allowed for continuously inundated ecological condition, which created a salinity gradient from freshwater at spring discharge locations to hypersaline conditions in locations distant from springs. Saline lakes support a unique flora and fauna community including numerous species of conservation concern (e.g., interior snowy plover [Charadrius nivosus]). Due to a historical dependable water availability, saline lakes support shorebird migration from across North America. However, exploitation of the Ogallala Aquifer has resulted in the reduction and frequent cessation of spring discharge into saline lakes. We used LandSat imagery to estimate percent inundation of each saline lake from 1973-2012. We established groups of saline lakes based on spatial position and assessed 1) first occurrence of complete drying for individual saline lakes, 2) changes over time of percent inundation for individual saline lakes and grouped saline lakes by season, and 3) contemporary capacity of saline lakes to support historical flora and fauna. Only 4 saline lakes maintained inundated conditions during the study period. Northern saline lakes experienced complete drying starting in the 1970s, whereas drying of southern saline lakes became common during the past two decades. The dominant spatial pattern of drying was from the northwest to the southeast. Essentially, the ecological state of nearly all saline lakes has changed from a continuous inundation state to one dependent upon unpredictable, intensive precipitation events for inundation. The long-term effects of such a dynamic ecological state change on endemic flora and fauna are unknown, but preliminary data indicate local extinctions of many species from communities supported by saline lakes.
2:30PM To Exclose Or Not? a Decision Support Tool for Piping Plover Management
Abigail Darrah; Jonathan Cohen; Paul Castelli
Nest exclosures are used to increase nest success of the threatened U.S. Atlantic Coast piping plover (Charadrius melodus) population, but they also increase nest abandonment rates, which has been linked to adult mortality; thus exclosure use may not always benefit the population. The objective of our project was to create a decision support tool that predicts the population-level effects of exclosure use. We analyzed piping plover nest fate data collected in 2015 from 46 sites using a Bayesian multinomial logistic exposure model to estimate the effects of exclosure use on probabilities of nest depredation and abandonment, with site modeled as a random effect. The estimated site variances and exclosure effects were used to calculate hatching and adult mortality probabilities under scenarios of 0% and 100% exclosure use and eight combinations of site-specific predation and abandonment rates. The hatching and mortality probabilities were incorporated into a two-stage stochastic projection model to estimate long-term population growth rates for each combination of management and site effects. Exclosure use at sites with high abandonment rates resulted in declining populations regardless of site predation risk, while exclosure use increased growth rates at sites with average abandonment rates and high predation. We have developed a web-based application that allows users to enter site characteristics and to upload nest fate data. The tool performs a Bayesian multinomial nest fate analysis to estimate site-specific intercepts and exclosure effects, which are fed into the population projection model to predict the consequences of using vs. not using exclosures. Our methods and tool can be readily adapted for other species for which nest exclosures are a management technique.
2:50PM Refreshment Break
3:20PM Piping Plover Population Irruptions Following Habitat Creating Events
Samantha G. Robinson; James D. Fraser; Daniel H. Catlin; Sarah M. Karpanty; Kelsi L. Hunt; Ruth Boettcher; Alexandra Wilke; Kevin Holcomb; Jon Altman
Effective management of imperiled wildlife populations requires identification of population limiting factors. Piping plovers (Charadrius melodus), are threatened, and habitat loss has been blamed. Piping plovers are a disturbance-dependent species, nesting on sparsely-vegetated beaches and sandbars. Habitat loss can occur through vegetation encroachment on nesting areas, if they are not periodically overwashed, as well as shoreline erosion. Habitat creation in these systems occurs through sand movement and deposition from storm fueled overwash and floods. To determine the effects of overwashing on plover populations, we classified aerial imagery with object-based classification tools, pre- and post-disturbance, quantifying nesting habitat. Storms and floods that we considered were Hurricane Isabel on barrier islands of Virginia and North Carolina in 2003, Hurricane Irene and Hurricane Sandy on Cedar Island in Virginia in 2011 and 2012, the strong northeaster that struck of Assateague Island, Maryland in 1991, and the floods of 1993 and 2011 on the Missouri River between South Dakota and Nebraska. The amount of nesting habitat increased 27%–950% in sites studied, and piping plover populations increased 71%–450% after these events. At our smallest site, we saw an increase of 18 pairs, whereas at our largest site, we saw an increase of 132 pairs corresponding with increases in nesting habitat. The greatest population increases occurred in areas where the event increased access to low wave energy, moist substrates, which piping plovers use as foraging habitat. Currently, human interventions such as artificial dunes and dams reduce natural disturbance. If these interventions were reduced, plover populations would likely reach higher average numbers.
3:40PM Heading for Higher Ground: Adapting Marsh Bird Management as Sea Level Rises
Paul J. Taillie; Christopher E. Moorman; Benjamin Poulter
Coastal ecosystems provide important ecosystem services, including habitat for diverse and unique wildlife communities. As climate change causes sea level to rise at an increasing rate, novel wildlife management approaches in coastal regions will be required to address emerging management challenges. To better understand the effects of rising sea level and altered disturbance regimes related to climate change, we replicated a 2004 study of vegetation conditions across a gradient of saltwater exposure and fire history on the Albemarle-Pamlico Peninsula, NC. In addition, we conducted surveys of marsh birds at 95 points distributed across brackish marshes in the same region in 2016. In forested plots at the inland edge of coastal marshes, live tree density decreased by 25-100% (mean=66%), despite no history of recent fire (since 2004), but tree density increased at plots that were not susceptible to saltwater exposure. Furthermore, all plots affected by a combination of saltwater exposure and fire underwent a complete transition to marsh by removal of the forest canopy, limited tree regeneration, and invasion of marsh grasses into previously forested areas. Virginia rail (Rallus limicola) used newly-created marshes in the wake of recent fire, which indicates the landward migration of coastal marshes may benefit birds associated with high marsh. We expect similar benefits for the rare black rail (Laterallus jamaicensis), though we did not detect enough individuals to show this statistically. Our results indicate the use of prescribed fire to facilitate the landward migration of coastal marshes may greatly benefit marsh-associated birds as sea level continues to rise. However, such an approach would exacerbate the already extensive forest loss documented in low-lying coastal regions. We recommend future investigation of these tradeoffs in ecosystem services to guide development of novel wildlife management approaches that consider a changing climate.
4:00PM Demographic Consequences of Road Mortality to Snowy Plovers in Northwest Florida
Maureen M. Durkin; Jonathan Cohen
Gulf Islands National Seashore (GUIS) is a large barrier island park system that holds up to 20% of the breeding population of state-threatened Snowy Plovers (Charadrius nivosus) in Florida. Despite its regional importance, reliable estimates of productivity and survival of Snowy Plovers at GUIS are lacking. Further, over 14 miles of public roadway bisect the park- directly through plover nesting and foraging habitat. Opportunistic documentation of shorebirds killed by vehicle collisions raised concern about the issue among managers, but systematic attempts to measure mortality have not been previously undertaken. To accurately estimate the number of Snowy Plovers killed by vehicles, we conducted systematic carcass surveys from 2013-2016. We also intensively monitored Snowy Plover nests and chicks to establish baseline productivity estimates. We found that in some areas, as many as 10% of adults, 15% of chicks, and 25% of fledglings were killed on the road in a single breeding season. In addition to direct mortality, we observed that death of nesting adults on the road could result in subsequent nest abandonment by the surviving mate. We used demographic parameters from our monitoring in a population viability analysis, incorporating road mortality rates as a hazard. We modeled the probability of extinction of both local and regional populations under current conditions, and also under different road mortality and productivity scenarios that could result from management actions. Our modeling indicates that Snowy Plovers in Northwest Florida exhibit source-sink dynamics, and GUIS is currently a regional sink-unable to sustain itself without an influx of recruits from other sites. While road mortality is a significant contributor to the role of GUIS as a sink, the issue is exacerbated by high rates of reproductive failure attributable to predators. Potential management actions aimed at stabilizing this population should address both road mortality and low productivity issues.
4:20PM Developing Range-Wide Occupancy Models for King Rails: Optimizing Predictive Capabilities Across Spatial Scales
Bryan S. Stevens; Courtney J. Conway
Models are commonly used for predicting distributions of animals and characterizing wildlife-habitat relationships. Distribution models play a pivotal role in prioritizing habitat management, yet their predictions are limited by scale-sensitivity of habitat relationships and the difficulty of assessing model performance with occurrence data. King rails (Rallus elegans) are a widely distributed species of marsh bird whose populations have declined across portions of their breeding range, thus spatial prioritization of existing habitats for this species is desirable. Our objective was to develop models that predict king-rail occupancy as a function of habitat characteristics across their entire breeding range. We used data from surveys conducted over a 14-year period (1999-2012) at 3,650 sites in 27 U.S. states to develop hierarchical occupancy models, and used Bayesian model selection and scale-optimization techniques to optimize the model structure for predictive purposes. We randomly split survey data into 60/40 training-testing data sets: we used data from 2,190 sites to calibrate models and used the remaining 1,460 sites to test predictive ability of the models. We modeled king rail occupancy probability as a function of local-scale wetland variables and broad-scale watershed disturbance metrics measured at multiple spatial extents. We selected the optimal extent for each covariate, and then the optimal overall multi-scale model by selecting extents and covariates that maximized predicted probabilities of testing data using the logarithmic scoring rule. We demonstrate that king rail occupancy at a particular site is affected by both local-scale wetland characteristics and broad-scale watershed modification, and that our approach to scale optimization and multi-scale covariate selection produced models with superior predictive performance compared to commonly used alternatives. Thus, our models will be useful for predicting priority king rail habitats within their breeding range, and our analytical framework has broad applicability for developing multi-scale occupancy models for predictive purposes for any species.
4:40PM Gunnison Sage Grouse How Long Can the Crawford Population Persist?
Douglas S. Ouren; Brian Cade; Melissa Siders; Ken Holsinger
Because Gunnison Sage grouse (Centrocercus minimus) (GUSG) act as an indicator species in sagebrush ecosystems, it is critical to understand the dynamic complexities involved with GUSG habitat conservation. The objective of the project is to further understand these complexities to provide input for GUSG conservation management plans. Using resource selection analysis; examining demands on the landscape including wild and domestic ungulate grazing; exploration of impacts of humans and the effects of metrological variability provided a unique way of analyzing these landscape complexities. GUSG were recognized as a unique species with only seven distinct populations in 2000. In 2014 they were provided protection under the Endangered Species Act as a threatened species. The Crawford population has gone from an estimated high population of 315 in 1999 to the estimated population of 148 in 2016. This declining population trend is also seen in other GUSG sub populations which provide in the genetic viability for the range-wide population. With little data on Gunnison Sage Grouse and the sub populations, we initiated a collaborative effort with Federal Land Management agencies, state wildlife agencies and private land owners to increase the GUSG knowledge base and better understand the conservation requirements needed for this species to persist. Our methods include collecting 50,000 GPS locations representing approximately 10% of the Crawford GUSG population; developing camera trap networks; monitoring motorized use; initiating corvid surveys; evaluating ungulate (wild and domestic) grazing pressure; and evaluated effects of drought. Utilizing these data sets we have analyzed landscape relationships between GUSG with a variant of resource selection modeling tools. Our results indicate habitat constraints potentially include landscape fragmentation, limited mesic areas and impacts of grazing. We will demonstrate that the synthesis of this data provides valuable information for GUSG management plans.


Contributed Paper
Location: Albuquerque Convention Center Date: September 24, 2017 Time: 1:10 pm - 5:00 pm