Idaho Bird Observatory Publications and Presentations Copyright (c) 2013 Boise State University All rights reserved. http://scholarworks.boisestate.edu/ibo_facpubs Recent documents in Idaho Bird Observatory Publications and Presentations en-us Sat, 15 Jun 2013 01:47:38 PDT 3600 Predicting Nesting Habitat of Northern Goshawks in Mixed Aspen-Lodgepole Pine Forests in a High-Elevation Shrub-Steppe Dominated Landscape http://scholarworks.boisestate.edu/ibo_facpubs/16 http://scholarworks.boisestate.edu/ibo_facpubs/16 Thu, 13 Jun 2013 10:17:39 PDT We developed a habitat suitability model for predicting nest locations of breeding Northern Goshawks (Accipiter gentilis) in the high-elevation mixed forest and shrub-steppe habitat of south-central Idaho, USA. We used elevation, slope, aspect, ruggedness, distance-to-water, canopy cover, and individual bands of Landsat imagery as predictors for known nest locations with logistic regression. We found goshawks prefer to nest in gently-sloping, east-facing, non-rugged areas of dense aspen and lodgepole pine forests with low reflectance in green (0.53 - 0.61 μm) wavelengths during the breeding season. We used the model results to classify our 43,169 hectare study area into nesting suitability categories: well suited (8.8%), marginally suited (5.1%), and poorly suited (86.1%). We evaluated our model’s performance by comparing the modeled results to a set of GPS locations of known nests (n = 15) that were not used to develop the model. Observed nest locations matched model results 93.3% of the time for well suited habitat and fell within poorly suited areas only 6.7% of the time. Our method improves on goshawk nesting models developed previously by others and may be applicable for surveying goshawks in adjacent mountain ranges across the northern Great Basin.

]]> Robert A. Miller et al. Food Availability, Foraging Behavior, and Diet of Autumn Migrant Landbirds in the Boise Foothills of Southwestern Idaho http://scholarworks.boisestate.edu/ibo_facpubs/15 http://scholarworks.boisestate.edu/ibo_facpubs/15 Wed, 19 Sep 2012 10:58:54 PDT Food availability and acquisition are critical components of a stopover site's suitability, but we know relatively little about how changes in food availability affect the stopover ecology of migrating landbirds. We examined fruit and arthropod availability in three habitats, studied foraging behavior and diet, and investigated use versus availability for passerines migrating through southwestern Idaho in autumn. Hemiptera dominated foliage-dwelling arthropod communities in all three habitats, whereas Hymenoptera were most numerous among ground-dwelling arthropods. Mountain shrubland had relatively high biomass of both ground-dwelling and foliage-dwelling arthropods, whereas conifer forest had high biomass of foliage-dwelling arthropods only and shrub steppe had high biomass of ground-dwelling arthropods only. Species' foraging behavior varied, but most species foraged in mountain shrubland more often than expected by chance. Diets of most species included a high proportion of certain Hemiptera and Hymenoptera with smaller proportions of Coleoptera, Diptera, and Heteroptera; Coleoptera and some Hemiptera were consistently preferred by most species. Importantly, all 19 bird species examined consumed some fruit, and this is the first documentation of frugivory for two warbler species. These data point to the importance of several arthropod taxa, especially the Hemiptera and Hymenoptera, and fruits to landbirds migrating in mountain shrubland in autumn. Finally, we found no effect of annual variation of fruit or arthropod abundance on migrants' energetic condition, suggesting that food was sufficient for mass gain in all years of this study and/or that foraging behavior may be plastic enough to allow birds to gain mass despite annual differences in food availability.

]]> Jay D. Carlisle et al. Morphometric Variation in Flammulated Owls Captured During Autumn Migration in the Western United States http://scholarworks.boisestate.edu/ibo_facpubs/14 http://scholarworks.boisestate.edu/ibo_facpubs/14 Mon, 16 Apr 2012 13:13:38 PDT Knowledge of the migration geography of Flammulated Owls (Otus flammeolus) is limited. We combined data from multiple studies in the western United States to evaluate patterns of variation in Flammulated Owl morphometrics. Measurements from autumn migration study sites in New Mexico, Nevada, and Idaho followed a geographic cline from southeast to northwest across the species' range. Our objectives were to: (1) describe age- and sex-specific variation in the morphometrics of Flammulated Owls captured at the three sites, and (2) discuss the implications of this variation for understanding the species' migration geography. Based on a hierarchical series of factorial two-way ANOVAs, we discovered significant overall sex-specific differences in wing chord, exposed culmen length, and hallux length, and a consistent pattern of site-specific differences for most measurements. Most measurements increased from southeast to northwest, consistent with previous data on clinal variation in the species. Evidence of significant variation in the morphometrics of owls captured at the three migration sites suggests little longitudinal mixing of migrants in the region.

]]> Jeff P. Smith et al. How Safe is Mist Netting? Evaluating the Risk of Injury and Mortality to Birds http://scholarworks.boisestate.edu/ibo_facpubs/13 http://scholarworks.boisestate.edu/ibo_facpubs/13 Thu, 15 Sep 2011 12:12:10 PDT Summary

1. The capture of birds using mist nets is a widely utilized technique for monitoring avian populations. While the method is assumed to be safe, very few studies have addressed how frequently injuries and mortalities occur and the associated risks have not been formally evaluated.

2.  We quantified the rates of mortality and injury at 22 banding organizations in the United States and Canada and used capture data from five organizations to determine what kinds of incidents occur most frequently. Analyses focused on passerines and near-passerines, but other groups were included. We evaluated whether body mass, age, sex, mist net mesh size, month and time of day or frequency of capture are related to the risk or type of incident. We also compared the recapture histories over time between birds that were injured and those that were never injured for 16 species.

3.  The average rate of injury was 0·59%, while mortality was 0·23%. Birds captured frequently were less at risk to incident. Body mass was positively correlated with incident and larger birds were at greater risk to predation, leg injuries, broken legs, internal bleeding and cuts, while smaller birds were more prone to stress, tangling-related injuries and wing strain. Rates of incident varied among species, with some at greater risk than others. We found no evidence for increased mortality over time of injured birds compared with uninjured birds.

4.  We provide the first comprehensive evaluation of the risks associated with mist netting. Our results indicate that (1) injury and mortality rates below one percent can be achieved during mist netting and (2) injured birds are likely to survive in comparable numbers to uninjured birds after release. While overall risks are low, this study identified vulnerable species and traits that may increase a bird’s susceptibility to incident that should be considered in banding protocols aimed at minimizing injury and mortality. Projects using mist nets should monitor their performance and compare their results to those of other organizations.

]]> Erica N. Spotswood et al. Relative Efficiency of Fecal Versus Regurgitated Samples for Assessing Diet and the Deleterious Effects of a Tartar Emetic on Migratory Birds http://scholarworks.boisestate.edu/ibo_facpubs/12 http://scholarworks.boisestate.edu/ibo_facpubs/12 Mon, 25 Jul 2011 12:11:39 PDT We describe the deleterious effects of using an antimony potassium tartrate emetic to obtain diet samples from birds, and compare information obtained from regurgitated samples versus fecal samples in describing diets of autumn migrants. We also examined dose effectiveness in captive Dark-eyed Juncos (Junco hyemalis) subjected to the same emetic technique used in the field. Over 70% of migrants given an emetic at a study site in Idaho regurgitated useful samples. For 5 of 7 species analyzed, regurgitated samples produced significantly more arthropods per sample than fecal samples, and one species, Warbling Vireo, showed higher numbers of distinct arthropod taxa per sample. In most species, regurgitated samples accumulated arthropod taxa more quickly than fecal samples. However, increasing the number of fecal samples by 5–17 produced a similar number of taxa. Diet composition based on fecal versus regurgitated samples was generally similar, but there were significant differences. Two of 130 treated migrants died soon after treatment. Recapture frequency for treated birds was less than half that for untreated birds, but it is not clear whether this difference was due to treatment-related mortality or emigration. Each treated bird that we recaptured had lost mass and this suggests a deleterious effect because untreated migrants tended to gain mass. In captivity, 18 Dark-eyed Juncos were treated with emetic: 6 with the full mass-specific recommended dose, 6 with half the recommended dose, and the final 6 with one quarter the recommended dose. All were alive 15–20 min posttreatment (recommended release time), but 17 of 18 died within 30 min after receiving the emetic. Together, our data suggest that although the emetic technique may be slightly more information-rich in assessing diet, it is more harmful than previously reported especially in certain species and should be used only after adequate consideration of the immediate mortality and short-term physiological effects on birds to be studied.

]]> Jay D. Carlisle et al. Status of the Broad-Winged and Red-Shouldered Hawks During Fall Migration in Southwestern Idaho, 1995-2006 http://scholarworks.boisestate.edu/ibo_facpubs/11 http://scholarworks.boisestate.edu/ibo_facpubs/11 Tue, 12 Jul 2011 14:09:46 PDT Twelve years of counting raptors during fall migration near Boise, Idaho, yielded 214 Broad-winged and 9 Red-shouldered Hawks, revealing these species as much more frequent in Idaho than previously known. The Broad-winged Hawk is an uncommon, annual fall migrant in Idaho. The Red-shouldered Hawk is at least casual, possibly nearly annual, during fall migration. These data match increased sightings from other western states that have likely resulted from a combination of increased observer coverage and possible range expansions and/or numerical increases for both species in the West.

]]> Jay D. Carlisle et al. Breeding Bird Inventory of Spirit Mound Historic Prairie in Clay County - An Area Being Restored to Tallgrass Prairie http://scholarworks.boisestate.edu/ibo_facpubs/10 http://scholarworks.boisestate.edu/ibo_facpubs/10 Tue, 12 Jul 2011 14:05:50 PDT Jay D. Carlisle et al. Autumn Landbird Communities in the Boise Foothills and Owyhee Mountains of Southwestern Idaho http://scholarworks.boisestate.edu/ibo_facpubs/9 http://scholarworks.boisestate.edu/ibo_facpubs/9 Tue, 12 Jul 2011 13:59:30 PDT Identifying important stopover areas is a critical step in conservation and management of migratory birds, and relatively little effort has been directed toward this task in Idaho or the Intermountain West. We used mist-net captures to describe the relative abundance, species richness, and community similarity of autumn migrant landbirds in the Boise Foothills and Owyhee Mountains of southwestern Idaho, two mountain ranges separated by the Snake River Plain. We captured birds at three mist-net sites from August to October 1998. Two sites were situated in the Boise Foothills, one in deciduous mountain shrubland, the other in an adjacent willow-dominated riparian draw; the third site was at a riparian spring in the Owyhee Mountains. Capture rates for resident species, temperate-zone migrants, and irruptive migrants were highest at the Boise Foothills riparian site, whereas the Boise Foothills mountain shrubland site had the highest abundance of neotropical migrants. Species richness was highest at the two Boise Foothills sites, but at all sites diversity and evenness were similar. Among the three sites, the two Boise Foothills sites (mountain shrubland and willow riparian) had the most similar bird communities. Capture rates were high (> 1 bird per mist-net hour) at all three sites, and these results demonstrate that many species of autumn migrants occur frequently in montane deciduous habitats across southwestern Idaho.

]]> Jay D. Carlisle et al. Comparative Ecology of the Flammulated Owl and Northern Saw-Whet Owl During Fall Migration http://scholarworks.boisestate.edu/ibo_facpubs/8 http://scholarworks.boisestate.edu/ibo_facpubs/8 Tue, 12 Jul 2011 13:53:30 PDT We compared the migration ecology of two owl species that exhibit different migration strategies: the Flammulated Owl (Otus flammeolus) and the Northern Saw-whet Owl (Aegolius acadicus). During fall 1999–2004, we captured 117 Flammulated Owls and 1433 Northern Saw-whet Owls in the southern Boise Mountains of southwestern Idaho. These owl species exhibited contrasting seasonal timing and body condition. Flammulated Owl captures peaked in mid-September and Northern Saw-whet Owl captures peaked in early to mid-October. Flammulated Owls displayed greater body condition than Northern Saw-whet Owls and increasing condition scores during the season, whereas Northern Saw-whet Owls had no apparent seasonal condition patterns. Based on seasonal timing of captures, both species showed unimodal movement patterns characteristic of fall migrants. However, in 1999 both species’ capture rates were at least double those in other years of this study. Flammulated Owls’ earlier arrival and departure, coupled with superior body condition, were consistent among years and typical of a longdistance migration strategy. In contrast, the Northern Saw-whet Owls’ later arrival, more lengthy passage, and variable body condition were more characteristic of a short-distance migrant strategy. Furthermore, Northern Saw-whet Owls’ body condition was significantly lower during the irruptive year than during nonirruptive years, supporting the notion that population density affects their migratory condition.

]]> Sarah L. Stock et al. Towards the Establishment of Landbird Migration Monitoring Networks in the United States http://scholarworks.boisestate.edu/ibo_facpubs/7 http://scholarworks.boisestate.edu/ibo_facpubs/7 Tue, 12 Jul 2011 12:55:45 PDT Migration monitoring of landbirds, in its various forms, is a well-established research endeavor across much of North America. While monitoring efforts at individual sites have contributed much to our knowledge of the biology of migrants, these studies have limited potential for population monitoring and for addressing certain broader questions about migrants. Meanwhile, there is still much to be learned about the habitat use, conservation needs, population trends, demographics, and general stopover ecology of migrants. As a model for migration monitoring networks, the establishment and operation of monitoring and research networks for other purposes in avian research has met with much success. We suggest that the involvement of many monitoring sites in a larger network can provide unique and necessary research, conservation, and monitoring opportunities for the study of birds during migration. While many are willing and eager to participate in such networks, the critical issue has been the ability of institutions to afford personnel to coordinate them. Here we review historical and present networks devoted to avian research and consider applications to the development of migration monitoring networks in the Americas.

]]> Jay D. Carlisle et al. Molt Strategies and Age Differences in Migration Timing Among Autumn Landbird Migrants in Southwestern Idaho http://scholarworks.boisestate.edu/ibo_facpubs/6 http://scholarworks.boisestate.edu/ibo_facpubs/6 Tue, 12 Jul 2011 12:21:27 PDT Intraspecific patterns of autumn migration timing are not well known, particularly in the western United States. Here, we (1) describe autumn migration timing and age ratios of landbird migrants in southwestern Idaho, (2) examine differences in timing among age and sex classes, and (3) demonstrate how prebasic molt strategies affect migration timing differences between age classes. As a group, Neotropical migrants were most common from late July through early September, whereas temperate migrants were most common from mid-September into early October. Proportion of hatch-year birds was 74.5% for all migrants combined and ranged from 33.3% to 100% for individual species. Timing differences between sex classes were detected in only a few species and no general patterns emerged. In 22 of 31 Neotropical and temperate migrants examined, there were significant differences in timing between adults and hatch-year birds. In species in which adults begin fall migration before replacing flight feathers, adults migrated earlier than hatch-year birds. Conversely, in species in which adults molt flight feathers on or near the breeding grounds before departing on fall migration, hatch-year birds migrated earlier than adults in all but one case. Therefore, it appears that molt strategy is a powerful determinant of intraspecific migration timing differences and, to our knowledge, this is the first study to document this pattern among migrant passerines of North America.

]]> Jay D. Carlisle et al. Species Richness and Nesting Success of Migrant Forest Birds in Natural River Corridors and Anthropogenic Woodlands in Southeastern South Dakota http://scholarworks.boisestate.edu/ibo_facpubs/5 http://scholarworks.boisestate.edu/ibo_facpubs/5 Mon, 11 Jul 2011 16:22:08 PDT Forest fragmentation is thought to be partially responsible for declines in many Neotropical migrant birds due to the combined effects of higher rates of brood parasitism and increased predation near forest edges. A majority of the forested habitat in the northern prairie region is found in riparian corridors, but this native habitat has been much reduced from its historical extent. However, additional woodland nesting habitat has been established within the last century in the form of isolated woodlots on farms. We compared abundance, species richness, and nesting success of migrant forest birds breeding in native riparian corridors and anthropogenic woodlots. The two habitats had similar bird abundances but native riparian woodlands were more species-rich than woodlots. We located a total of 650 nests, with 320 nests of 15 species in woodlots and 331 nests of 25 species in riparian corridors. Nesting success was not significantly different between the two habitats for all species combined or for individual species with ≥15 nests in each habitat. Nests above 5 m were more successful than lower nests, but distance to woodland edge did not influence nesting success. Nests initiated in the middle and late portions of the nesting season were more successful than early season nests, significantly so in woodlots. Thus, anthropogenic woodlots were as suitable as natural habitats for successful nesting. However, many of the Neotropical migrants occurring in riparian habitats were absent from woodlots, which suggests that riparian corridors are especially important habitats for breeding birds in the northern prairie region.

]]> Dale J. Gentry et al. Stopover Ecology of Autumn Landbird Migrants in the Boise Foothills of Southwestern Idaho http://scholarworks.boisestate.edu/ibo_facpubs/4 http://scholarworks.boisestate.edu/ibo_facpubs/4 Mon, 11 Jul 2011 16:09:33 PDT The topography of western North America provides a complex landscape for landbird migrants, and stopover patterns in this region are poorly understood. We examined seven years of stopover data (1997–2003) from a montane area in southwestern Idaho to determine whether this area provides suitable stopover habitat. We compared the proportion of birds recaptured, stopover duration, and changes in energetic condition within and among species and between two mist-netting sites located in different habitats. The proportion of birds recaptured ranged from zero to over 20%, and fewer than 5% of individuals were recaptured in most species. Mean minimum stopover durations from recapture data ranged from 1 to 10 days; most species averaged less than 6 days. Stopover duration estimates from open-population models were comparable but generally greater than estimates from recapture data. As found in stopover studies from other regions, stopover metrics varied within and among species in Idaho. However, most migrants in this study exhibited an ability to gain mass, evidenced both by recapture data and by regression of energetic condition against time since sunrise. These data imply that montane habitats in Idaho are suitable stopover sites. It follows that these habitats might serve an important role for many landbird migrants during the period of late summer molt and autumn migration, a time when many lowland areas of the West, including some riparian systems, are especially arid. We suggest that including montane nonriparian habitats in future stopover ecology studies will allow for a more complete understanding of migrant habitat needs in the West.

]]> Jay D. Carlisle et al. Habitat Associations, Relative Abundance, and Species Richness of Autumn Landbird Migrants in Southwestern Idaho http://scholarworks.boisestate.edu/ibo_facpubs/3 http://scholarworks.boisestate.edu/ibo_facpubs/3 Mon, 11 Jul 2011 15:57:15 PDT We used count surveys and mist-net captures to compare habitat associations, relative abundance, species richness, and community similarity of migrant landbirds among four major habitats in the Boise Foothills of southwestern Idaho. Count surveys were conducted from August through October 1997–2000 in conifer forest, mountain shrubland, shrubsteppe, and riparian shrubland. We compared bird detections among habitats for all birds pooled, individual species, and three migration strategies: Neotropical, temperate, and resident (including irruptive migrants). Mountain shrubland supported the highest numbers of temperate migrants; both mountain shrubland and riparian shrubland had the highest numbers of Neotropical migrants; and conifer forest had the highest numbers of residents. Species richness was highest in riparian shrubland and lowest in shrubsteppe, whereas diversity and evenness were highest in conifer forest and mountain shrubland. Mist netting was conducted from mid-July to mid-October in two habitats: mountain shrubland (1997– 2002) and riparian shrubland (1998–1999). Captures (adjusted for effort) were compared among habitats in 1998–1999 and were similar for temperate migrants, whereas mountain shrubland had higher abundance of Neotropical migrants and riparian shrubland had higher abundance of irruptive migrants. Richness, diversity, and evenness were similar and there was high community similarity between mountain shrub and riparian shrubland habitats. These results emphasize the importance of montane habitats, especially deciduous shrub communities, to migrants in the Intermountain West.

]]> Jay D. Carlisle et al. Effects of Regional Cold Fronts and Localized Weather Phenomena on Autumn Migration of Raptors and Landbirds in Southwest Idaho http://scholarworks.boisestate.edu/ibo_facpubs/2 http://scholarworks.boisestate.edu/ibo_facpubs/2 Wed, 06 Jul 2011 12:53:44 PDT Weather has a significant effect on avian migration, but whether the influence is similar across diverse geographic regions and across all species remains to be determined. We evaluated the effect of regional cold fronts and localized weather phenomena on the timing of autumn migration of multiple species of landbirds and raptors in southwest Idaho. The focus of the analysis was on total landbirds and the ten most common landbird species, along with total raptors and the eight most common raptor species. Using 13 years of data from the Idaho Bird Observatory in southwest Idaho (1997–2009), including standardized mist-net captures of landbirds and counts of raptors during autumn migration, we determined significant patterns that advance our understanding of the variables influencing avian migration in the West. Our data show a depression of numbers of most migratory species on the days immediately before, during, and after the passage of a cold front, with peak flights of most species occurring several days prior to or after cold fronts. This pattern was further substantiated by a detailed analysis of many weather variables illustrating that the majority of species choose to migrate during calmer winds, high pressure, and between cold fronts when the opportunity presents itself. In the Intermountain West, cold fronts are fewer in fall than in much of the rest of North America, so migrants may have greater choice of conditions under which to migrate and this behavior may be more common.

]]> Robert A. Miller et al. Landbird Migration in the American West: Recent Progress and Future Research Directions http://scholarworks.boisestate.edu/ibo_facpubs/1 http://scholarworks.boisestate.edu/ibo_facpubs/1 Mon, 16 Aug 2010 08:30:12 PDT Our knowledge of avian behaviors during the non-breeding period still lags behind that of the breeding season, but the last decade has witnessed a proliferation in research that has yielded significant progress in understanding migration patterns of North American birds. And, although the great majority of migration research has historically been conducted in the eastern half of the continent, there has been much recent progress on aspects of avian migration in the West. In particular, expanded use of techniques such as radar, plasma metabolites, mist-netting, count surveys, stable isotopes, genetic data, and animal tracking, coupled with an increase in multi-investigator collaborations, have all contributed to this growth of knowledge. There is increasing recognition that migration is likely the most limiting time of year for migratory birds, and this places increasing importance on continuing to decipher patterns of stopover ecology, identifying critical stopover habitats, and documenting migration routes in the diverse and changing landscapes of the American West. Here, we review and briefly synthesize the latest avian migration findings and advances and consider research needs to guide future research on migration in the West.

]]> Jay D. Carlisle et al.