Microhabitat Characteristics of Lapland Longspur, Calcarius lapponicus, Nests at Cape Churchill, Manitoba

We examined microsite characteristics at 21 Lapland Longspur (Calcarius lapponicus) nests and land cover types in which they occurred in Wapusk National Park, Cape Churchill, Manitoba. Nests were located in four of six physiographic-vegetation land-cover types. Regardless of land-cover type, all but one nest was built on a pressure ridge or mound. Nests were built midway between the bottom and top of ridges or mounds with steeper slopes than was randomly available. Longspur nests had a distinctive southwest orientation (P < 0.001). Longspurs selected nest sites that consisted of comparatively greater amounts of shrub species and lesser amounts of moss than were randomly available. Nests were generally well concealed by vegetation (mean = 67.0%) and concealment was negatively associated with amount of graminoid species at the nest (P = 0.0005). Our nesting habitat data may facilitate a better understanding of breeding Lapland Longspur habitat requirements, and potential impacts of habitat degradation by increasing Snow Goose (Chen caerulescens) populations in the study area

Nest-defense Behavior of Mississippi Kites in Urban and Exurban Areas

Mississippi kites (Ictinia mississippiensis) have become an abundant raptor in many urban and exurban areas throughout the Southern Great Plains of the United States. Unfortunately, human–wildlife conflicts have resulted from this juxtaposition of suitable breeding areas for kites and areas that humans frequent, with some kites responding aggressively to humans near nests. To date, there are no data describing the prevalence of aggressive nest defense in the species, making informed management of human and kite conflicts difficult. We assessed and compared the prevalence of aggressive nest-defense by Mississippi kites in an urban area and an exurban area by simulating nest disturbance with a trial pedestrian. Additionally, we examine the relationships between physical features of the nest tree where aggressive behaviors were and were not recorded. Individual kites breeding in the exurban area responded to the trial pedestrian by taking flight from the nesting area, circling overhead, swooping at the pedestrian, or remaining on the nest. In the urban area, kites displayed a more limited suit of responses and either remained on the nest or swooped at the pedestrian. Additionally, kites breeding in the exurban area appeared to respond to experimental disturbance at a greater distance than did urban breeding kites, but not with more attacks on pedestrians. Physical characteristics of the nest tree did not explain aggressive behaviors, thereby suggesting that aggression in Mississippi kites is caused by factors other than nesting location features

Microhabitat Characteristics of Lapland Longspur, Calcarius lapponicus, Nests at Cape Churchill, Manitoba

We examined microsite characteristics at 21 Lapland Longspur (Calcarius lapponicus) nests and land cover types in which they occurred in Wapusk National Park, Cape Churchill, Manitoba. Nests were located in four of six physiographic-vegetation land-cover types. Regardless of land-cover type, all but one nest was built on a pressure ridge or mound. Nests were built midway between the bottom and top of ridges or mounds with steeper slopes than was randomly available. Longspur nests had a distinctive southwest orientation (P < 0.001). Longspurs selected nest sites that consisted of comparatively greater amounts of shrub species and lesser amounts of moss than were randomly available. Nests were generally well concealed by vegetation (mean = 67.0%) and concealment was negatively associated with amount of graminoid species at the nest (P = 0.0005). Our nesting habitat data may facilitate a better understanding of breeding Lapland Longspur habitat requirements, and potential impacts of habitat degradation by increasing Snow Goose (Chen caerulescens) populations in the study area

CALL BROADCASTING AND AUTOMATED RECORDERS AS TOOLS FOR ANURAN SURVEYS IN A SUBARCTIC TUNDRA LANDSCAPE

Relatively little is known about population ecology of anurans in arctic and subarctic tundra regions, in part because it is difficult to survey anurans in these landscapes. Anuran survey protocols developed for temperate regions have limited applicability in arctic and subarctic tundra landscapes, which may lack roads and vehicle access, and experience variable and inclement weather during short anuran breeding seasons. To evaluate approaches to address some of the limitations of surveying anurans in tundra landscapes, we assessed the effectiveness of using breeding call broadcasts to increase detection of Boreal Chorus Frogs (Pseudacris maculata) and Wood Frogs (Lithobates sylvaticus) near Cape Churchill, Manitoba, Canada. We also evaluated how counts of anurans derived from automated audio recorders compared with those obtained simultaneously by observers. We detected on average 0.4 additional Wood Frogs per survey when we broadcasted calls (x = 0.82, SD = 1.38), an increase of > 40% compared to surveys without broadcasts (x = 1.24, SD = 1.51; Wilcoxon test; Z = 2.73, P = 0.006). In contrast, broadcasting Boreal Chorus Frog calls did not increase the number of chorus frog detections (Wilcoxon test; Z < 0.001, P > 0.90). Detections of Wood Frogs in a 100-m radius were lower via automated recorders (x = 0.60, SD = 0.87 SD) than by observers during simultaneous surveys (x = 0.96, SD = 1.27 Z = 2.07, P = 0.038), but those of Boreal Chorus Frogs were not different (x = 1.72, SD = 1.31;x = 1.44, SD = 1.5; Z = 1.55, P > 0.121). Our results suggest that broadcasting calls can increase detection of Wood Frogs, and that automated recorders are useful in detecting both Wood Frogs and Boreal Chorus Fogs in arctic and subarctic tundra landscapes

Threat Avoidance Behavior and Land Use of the Northern Bobwhite in the Rolling Plains of Texas

Northern bobwhites (Colinus virginianus) are an economically important species for several regions within the state of Texas. Bobwhites, along with their fiscal importance, fill a key role within the ecosystem as an r-selected common prey species. However, throughout the past few decades, bobwhite populations have plummeted to record lows. Currently many studies are investigating possible causes behind this precipitous decline, but efforts to discover better land management practices that provide preferred habitat for bobwhites should not be abandoned. Current landscape recommendations related to bobwhite escape cover stem from data collected on anthropogenic threats to bobwhites (i.e., coveys flushed by human disturbance). Bobwhites have a multitude of non-anthropogenic threats in the wild, and the existing data may lack important information regarding threat-specific avoidance behavior. Predation is a primary cause of bobwhite mortality, and we focused on bobwhite anti-predatory behavior and resulting land-use strategies with an ultimate goal of providing management recommendations to increase bobwhite survival. We designed and conducted an experiment to investigate not only bobwhite responses to anthropogenic threats, but also their responses to common natural predators. We investigated bobwhite behavioral and use of cover actions in response to 4 threat types: researchers, hunters, raptors, and nocturnal mammals. We collected data from January through March in 2010 and from November 2010 through March 2011. We measured characteristics of bobwhite flushing behavior, flight speed, and land and vegetative use when presented with specific threats. We located radio-marked coveys and conducted a walk-through for the researcher threat, if necessary, to cause the birds to flush. The hunter and raptor threats were conducted similarly with introduction of pointing dogs and shotgun blasts for the hunting scenario, and introduction of a trained northern goshawk (Accipiter gentilis) to give chase to bobwhites in the raptor scenario. We followed the same methods as the researcher treatment when creating the nocturnal mammal treatment, but conducted the test at night and followed the birds’ flight with a thermal imaging scope. There was a significant difference in landing cover among threat types with bobwhites selecting shrubs for landing cover when pursued by a raptor (P , 0.0001), whereas they showed no selection for shrubs when flushed by the other threat types. Bobwhites landed in live oak (Quercus virginianus) mottes and hackberry (Celtis reticulata) shrubs with the highest frequency, followed closely by wolfberry (Lycium barbarum), lote bush (Ziziphyus obtusifolia), and Englemann’s pricklypear (Opuntia engelmannii) when escaping the raptorial threat, These 5 species accounted for 49% of all shrubs used (19 total species) as escape cover in the raptor treatment. Obstructive vegetative height was higher at landing sites when bobwhites were presented with a raptor (P , 0.0001) or hunter (P 1⁄4 0.033) threat; however, bobwhites displayed no selection for obstructive vegetative height when presented with a researcher or nocturnal mammal threat. Further analyses will include modeling environmental and experimental parameters to find likely predictors of bobwhite threat avoidance behaviors, such as flushing speed, flight speed, and flight distance; behaviors that arguably affect energy expenditure and may interact with bobwhite health and predator avoidance capabilities. Our results suggest that land management recommendations based solely on anthropogenic threats may be insufficient to enable successful bobwhite escape strategies from raptors. Considering the availability and ‘integrity’ of shrubs as escape cover from raptors when contemplating brush management plans may enhance bobwhite management. We expect to provide threat-specific land management recommendations for bobwhites related to shrub species and density as well as grass density with continued analysis of these data

Vertical structure use by the Stout Iguana (Cyclura pinguis) on Guana Island, BVI

The Stout Iguana (Cyclura pinguis) is a critically endangered species endemic to the Puerto Rico Bank and currently restricted to the British Virgin Islands (BVI). Our study on Guana Island, BVI, focused on vertical structure use by adult (n = 4) and juvenile (n = 11) iguanas with tracking bobbins. We recorded structure types used, heights attained on structures, distances between structures, and structure sizes. We found that Stout Iguanas used vertical structure more than previously documented. Trees comprised a significantly greater (P <  0.001) proportion of structures used by juveniles than by adults, whereas rocks comprised the greatest proportion of structures used by adults. In addition to differential structure use, juveniles climbed significantly higher (2.4 vs. 0.9 m on average; P < 0.001) than adults. We found no difference in the diameter or distance between structures used by adults and juveniles. Our results suggest that vertical structure use may be an important habitat element for free-ranging juvenile Stout Iguanas. Habitat management that provides vertical structure may be advantageous for the conservation of this species

Interactive effects between nest microclimate and nest vegetation structure confirm microclimate thresholds for Lesser Prairie-Chicken nest survival

Citation: Grisham, B. A., Godar, A. J., Boal, C. W., & Haukos, D. A. (2016). Interactive effects between nest microclimate and nest vegetation structure confirm microclimate thresholds for Lesser Prairie-Chicken nest survival. Condor, 118(4), 728-746. doi:10.1650/CONDOR-16-38.1The range of Lesser Prairie-Chickens (Tympanuchus pallidicinctus) spans 4 unique ecoregions along 2 distinct environmental gradients. The Sand Shinnery Oak Prairie ecoregion of the Southern High Plains of New Mexico and Texas is environmentally isolated, warmer, and more arid than the Short-Grass, Sand Sagebrush, and Mixed-Grass Prairie ecoregions in Colorado, Kansas, Oklahoma, and the northeast panhandle of Texas. Weather is known to influence Lesser Prairie-Chicken nest survival in the Sand Shinnery Oak Prairie ecoregion; regional variation may also influence nest microclimate and, ultimately, survival during incubation. To address this question, we placed data loggers adjacent to nests during incubation to quantify temperature and humidity distribution functions in 3 ecoregions. We developed a suite of a priori nest survival models that incorporated derived microclimate parameters and visual obstruction as covariates in Program MARK. We monitored 49 nests in Mixed-Grass, 22 nests in Sand Shinnery Oak, and 30 nests in Short-Grass ecoregions from 2010 to 2014. Our findings indicated that (1) the Sand Shinnery Oak Prairie ecoregion was hotter and drier during incubation than the Mixed- and Short-Grass ecoregions; (2) nest microclimate varied among years within ecoregions; (3) visual obstruction was positively associated with nest survival; but (4) daily nest survival probability decreased by 10% every half-hour when temperature was greater than 34°C and vapor pressure deficit was less than - 23 mmHg during the day (about 0600-2100 hours). Our major finding confirmed microclimate thresholds for nest survival under natural conditions across the species' distribution, although Lesser Prairie-Chickens are more likely to experience microclimate conditions that result in nest failures in the Sand Shinnery Oak Prairie ecoregion. The species would benefit from identification of thermal landscapes and management actions that promote cooler, more humid nest microclimates. © 2016 Cooper Ornithological Society