The influence of vegetation and landscape on the forest bird community of northeast Iowa

I studied bird community dynamics and habitat associations of forest birds in northeast Iowa in 1995 and 1996. During this study, 107 different bird species were detected in northeast Iowa forests, including many neotropical migrant songbirds. However, a nest parasite, the brown-headed cowbird ( Molothrus ater), was the most frequently detected bird during this study. The abundance and species richness of birds (both expressed as mean numbers per bird census point at each site) were both higher in 1995 but the rank orders of bird species in 1995 and 1996 were highly correlated, suggesting stable bird community structure over time;Most previous investigations of bird-habitat relationships conducted in Midwestern forests have excluded recently logged/pastured habitats. In this study, we included forests varying widely in area (32--486 ha) and disturbance history (forest preserves, recently logged/pastured forests, etc.). We discovered that bird species considered to be of high management concern by the U.S. Fish and Wildlife Service have higher species richness (mean number of species per census point at each site) in undisturbed forests than in recently disturbed forests. Species richness of these birds was also higher in large forest tracts than in smaller forests patches;Finally, we discovered that bird community composition shifts along a forest composition gradient, with many bird groups (e.g., neotropical migrants, USFWS high management concern species) tending to be more abundant and/or species rich in mesic forests. Most habitat associations were detected for only one year, demonstrating the need for long-term studies to truly understand bird community dynamics and the strength of these associations

A natural area inventory of Ames, Iowa

Perhaps no state in the Union has suffered such widespread degradation of its natural vegetation as Iowa. Tallgrass prairie (including wet prairie communities, often considered to be wetlands) once covered at least 85% of this state\u27s land area, but more than 99.9% of Iowa\u27s original grasslands have fallen victim to the plow (Smith 1990). Wetlands once covered 11.1% of Iowa\u27s landscape (Dahl 1990), but virtually all of these have been drained to make way for rowcrops (wetlands now cover only 1.2% of Iowa\u27s landscape). Roughly 12 to 20% of the state was covered by forest at the time of settlement by Europeans, but only 6% of the state is forest today (van der Linden and Farrar 1993, Leatherberry et al. 1992, Thomson and Hertel 1981). Furthermore, the majority of the forest fragments that do remain in Iowa are isolated and significantly altered by past grazing and/or logging practices

Probing the Off-State of Cluster Giant Radio Halos

We derive the best characterization to date of the properties of radio quiescent massive galaxy clusters through a statistical analysis of their average synchrotron emissivity. We stacked 105 radio images of clusters from the 843 MHz SUMSS survey, all with X-ray luminosities greater than 1.0E+44 erg/s and redshifts z < 0.2, after removing point-source contamination and rescaling to a common physical size. Each stacked cluster individually shows no significant large-scale diffuse radio emission at current sensitivity levels. Stacking of sub-samples leads to the following results: (i) clusters with L_{X} > 3.0E+44 erg/s show a 6-sigma detection of Mpc-scale diffuse emission with a 1.4 GHz luminosity of 2.4\pm0.4 x 1.0E+23 W/Hz. This is 1.5-2 times lower than the upper limits for radio quiescent clusters from the GMRT Radio Halo Survey (Venturi et al. 2008), and is the first independent confirmation of radio halo bi-modality; (ii) clusters with low X-ray concentrations have a mean radio luminosity (2.6\pm0.6 x 1.0E+23 W/Hz) that is at least twice that of high X-ray concentration clusters, and (iii) both of these detections are likely close to the low-level "off-state" of GRHs in most or all luminous X-ray clusters, and not due to contributions from a much smaller subset of "on-state" GRHs following the radio/X-ray luminosity correlation. Upcoming deep radio surveys will conclusively distinguish between these two options. We briefly discuss possible origins for the "off-state" emission and its implications for magnetic fields in most or all luminous X-ray clusters.Comment: 6 pages, 4 figures, accepted to ApJ Letter

Birds of the Navajo Country

journal articleThe Navajo country as covered in this paper lies in southeastern Utah and northeastern Arizona and is bounded on the north, west and south by the San Juan, Colorado, Little Colorado and Rio Puerco rivers and on the east by the Arizona-New Mexico state line. That part of the Navajo country lying in northwestern New Mexico, while not covered in this paper, is ecologically similar and is probably but little different faunistically

Astronomical photonics in the context of infrared interferometry and high-resolution spectroscopy

We review the potential of Astrophotonics, a relatively young field at the interface between photonics and astronomical instrumentation, for spectro-interferometry. We review some fundamental aspects of photonic science that drove the emer- gence of astrophotonics, and highlight the achievements in observational astrophysics. We analyze the prospects for further technological development also considering the potential synergies with other fields of physics (e.g. non-linear optics in condensed matter physics). We also stress the central role of fiber optics in routing and transporting light, delivering complex filters, or interfacing instruments and telescopes, more specifically in the context of a growing usage of adaptive optics.Comment: SPIE Astronomical Telescopes and Instrumentation conference, June 2016, 21 pages, 10 Figure

A Sr-Rich Star on the Main Sequence of Omega Centauri

Abundance ratios relative to iron for carbon, nitrogen, strontium and barium are presented for a metal-rich main sequence star ([Fe/H]=--0.74) in the globular cluster omega Centauri. This star, designated 2015448, shows depleted carbon and solar nitrogen, but more interestingly, shows an enhanced abundance ratio of strontium [Sr/Fe] ~ 1.6 dex, while the barium abundance ratio is [Ba/Fe]<0.6 dex. At this metallicity one usually sees strontium and barium abundance ratios that are roughly equal. Possible formation scenarios of this peculiar object are considered.Comment: 13 pages, 3 figures. Accepted to ApJ