Stopover Ecology of Autumn Landbird Migrants in the Boise Foothills of Southwestern Idaho

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

Species Richness and Nesting Success of Migrant Forest Birds in Natural River Corridors and Anthropogenic Woodlands in Southeastern South Dakota

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

Molt Strategies and Age Differences in Migration Timing Among Autumn Landbird Migrants in Southwestern Idaho

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

A re-assessment of the distribution of Virginia\u27s warbler in the Black Hills of South Dakota

Virginia’s Warbler (Oreothlypis virginiae) reaches the northeastern limit of its breeding range in the southern Black Hills of South Dakota, where it is considered a species of conservation concern. This population occurs in pine–juniper–shrub habitat in several canyons in extreme western Custer County. Additional such habitat occurs in the southern Black Hills south and east of the documented breeding populations, but these areas have received few systematic surveys, and whether Virginia’s Warbler occupies them was uncertain. Therefore, to define the species’ distribution in the South Dakota Black Hills more precisely, we surveyed with the aid of broadcast song and reviewed other reports. Virginia’s Warblers occurred in appropriate habitats all along the southwestern front (approximately 30 km total) of the Black Hills in Custer County but did not occur in similar habitat along the southeastern front, approximately 25 km distant. The species’ relative abundance in previously and newly identified pine–juniper–shrub habitats was similar. Virginia’s Warbler occurrence was positively associated with shrub cover (primarily mountain-mahogany, Cercocarpus montanus), pine overstory, and slopes of \u3e15°. Its association with the Spotted Towhee (Pipilo maculatus) was negative, with the Yellow-rumped Warbler (Setophaga coronata) tended toward positive, and with the Dusky Flycatcher (Empidonax oberholseri) was variable (negative along the southwestern front but weakly positive across all sites). These data extend the documented breeding range of Virginia’s Warbler in South Dakota by more than 20 km to the southeast. To clarify conservation priorities for this species at the northeastern limit of its range, future studies should delineate local and landscape-level characteristics of this population’s habitat more precisely and address its source–sink population dynamics

Habitat Associations, Relative Abundance, and Species Richness of Autumn Landbird Migrants in Southwestern Idaho

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

Food Availability, Foraging Behavior, and Diet of Autumn Migrant Landbirds in the Boise Foothills of Southwestern Idaho

Food availability and acquisition are critical components of a stopover site\u27s 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\u27 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\u27 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

Innovation as a Nonlinear Process, the Scientometric Perspective, and the Specification of an "Innovation Opportunities Explorer"

The process of innovation follows non-linear patterns across the domains of science, technology, and the economy. Novel bibliometric mapping techniques can be used to investigate and represent distinctive, but complementary perspectives on the innovation process (e.g., "demand" and "supply") as well as the interactions among these perspectives. The perspectives can be represented as "continents" of data related to varying extents over time. For example, the different branches of Medical Subject Headings (MeSH) in the Medline database provide sources of such perspectives (e.g., "Diseases" versus "Drugs and Chemicals"). The multiple-perspective approach enables us to reconstruct facets of the dynamics of innovation, in terms of selection mechanisms shaping localizable trajectories and/or resulting in more globalized regimes. By expanding the data with patents and scholarly publications, we demonstrate the use of this multi-perspective approach in the case of RNA Interference (RNAi). The possibility to develop an "Innovation Opportunities Explorer" is specified.Comment: Technology Analysis and Strategic Management (forthcoming in 2013

Magnetic field perturbation of neural recording and stimulating microelectrodes

To improve the overall temporal and spatial resolution of brain mapping techniques, in animal models, some attempts have been reported to join electrophysiological methods with functional magnetic resonance imaging (fMRI). However, little attention has been paid to the image artefacts produced by the microelectrodes that compromise the anatomical or functional information of those studies. This work presents a group of simulations and MR images that show the limitations of wire microelectrodes and the potential advantages of silicon technology, in terms of image quality, in MRI environments. Magnetic field perturbations are calculated using a Fourier-based method for platinum (Pt) and tungsten (W) microwires as well as two different silicon technologies. We conclude that image artefacts produced by microelectrodes are highly dependent not only on the magnetic susceptibility of the materials used but also on the size, shape and orientation of the electrodes with respect to the main magnetic field. In addition silicon microelectrodes present better MRI characteristics than metallic microelectrodes. However, metallization layers added to silicon materials can adversely affect the quality of MR images. Therefore only those silicon microelectrodes that minimize the amount of metallic material can be considered MR-compatible and therefore suitable for possible simultaneous fMRI and electrophysiological studies. High resolution gradient echo images acquired at 2 T (TR/TE = 100/15 ms, voxel size = 100 × 100 × 100 µm3) of platinum–iridium (Pt–Ir, 90%–10%) and tungsten microwires show a complete signal loss that covers a volume significantly larger than the actual volume occupied by the microelectrodes: roughly 400 times larger for Pt–Ir and 180 for W, at the tip of the microelectrodes. Similar MR images of a single-shank silicon microelectrode only produce a partial volume effect on the voxels occupied by the probe with less than 50% of signal loss.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58101/2/pmb7_8_003.pd

Lhx6 Delineates a Pathway Mediating Innate Reproductive Behaviors from the Amygdala to the Hypothalamus

In mammals, innate reproductive and defensive behaviors are mediated by anatomically segregated connections between the amygdala and hypothalamus. This anatomic segregation poses the problem of how the brain integrates activity in these circuits when faced with conflicting stimuli eliciting such mutually exclusive behaviors. Using genetically encoded and conventional axonal tracers, we have found that the transcription factor Lhx6 delineates the reproductive branch of this pathway. Other Lhx proteins mark neurons in amygdalar nuclei implicated in defense. We have traced parallel projections from the posterior medial amygdala, activated by reproductive or defensive olfactory stimuli, respectively, to a point of convergence in the ventromedial hypothalamus. The opposite neurotransmitter phenotypes of these convergent projections suggest a “gate control” mechanism for the inhibition of reproductive behaviors by threatening stimuli. Our data therefore identify a potential neural substrate for integrating the influences of conflicting behavioral cues and a transcription factor family that may contribute to the development of this substrate