Re-introduction of the Mallorcan midwife toad, Mallorca, Spain

The Mallorcan midwife toad (Alytes muletensis, Sanchíz & Alcover, 1977) or ferreret was first described in the 1970s as Baleaphryne muletensis from upper Pleistocene fossils, and was considered extinct. The discovery of live tadpoles in 1980 led to further research which confirmed the species as extant and endemic to Mallorca (Mayol & Alcover, 1981). Subfossils suggest that the species was once widespread across the island, but today it is confined to a few gorges within the Serra de Tramuntana mountains in the north-west part of the island. There are currently about 34 populations within the mountains and adjacent areas (16 original wild populations plus 18 re-introductions). These are largely isolated from each other by physiographic barriers, but there is little evidence of any inbreeding depression. Re-introduction of captive bred toads started in 1989 and it is estimated that about 25% of the wild toads stem from captive bred stock. The successful re-introduction program contributed to the downgrading of the species from ‘Critically Endangered’ to ‘Vulnerable’ in the Global Amphibian Assessment of 2004. There is little evidence that wild populations are continuing to decline, but the recent discovery of chytridiomycosis in four populations gives cause for concern

The toxic sheep collar for control of sheep-killing coyotes: A progress report

The toxic sheep collar is the most selective method known for killing coyotes that prey on domestic sheep. The concept dates back to the early 1900's and has been studied at the Denver Wildlife Research Center (DWRC) since 1974. Field tests with sodium cyanide (NaCN) in 1975 were unsuccessful due to repellent properties of the toxicant and to the apparent reluctance of coyotes to attack tethered lambs wearing bulky collars. Coyotes attacked one or more tethered, collared lambs in 7 of the 19 test pastures. In all, 14 collared lambs were attacked. Eight of the collars were punctured but no dead coyotes were recovered. A smaller collar containing diphacinone was field tested in 1976. The diphacinone-filled collars were readily accepted by coyotes and lethal to them, but the slow action (5-16 days between dosing and death) of diphacinone made it difficult to assess the effectiveness of these collars under field conditions. Target flocks containing 1 to 12 collared lambs plus uncollared ewes were placed in 15 fenced pastures from which the larger ranch flocks had been removed after repeated coyote predation. One or more collared lambs were attacked in 11 of the 15 tests. An unknown number of coyotes were killed, and in most tests the subsequent incidence of predation was lower than that before the test. Captive coyotes continued to kill sheep for 4 or 5 days after they received a lethal dose of diphacinone; therefore a faster-acting toxicant is needed. This research has shown that problem coyotes can be killed with toxic collars, but further studies are needed to determine the feasibility of this approach compared with traditional means of control. In most tests to date the frequency of coyote predation has been too low and too irregular to permit effective use of the collar; target flocks were in the field for an average of 10 days before being attacked. The known disadvantages of the method include the need to sacrifice live lambs, the human hazards associated with the use of toxicants under field conditions, and the costs of managing target flocks and other sheep in the problem areas

The Top Ten List of Gravitational Lens Candidates from the HST Medium Deep Survey

A total of 10 good candidates for gravitational lensing have been discovered in the WFPC2 images from the HST Medium Deep Survey (MDS) and archival primary observations. These candidate lenses are unique HST discoveries, i.e. they are faint systems with sub-arcsecond separations between the lensing objects and the lensed source images. Most of them are difficult objects for ground-based spectroscopic confirmation or for measurement of the lens and source redshifts. Seven are ``strong lens'' candidates which appear to have multiple images of the source. Three are cases where the single image of the source galaxy has been significantly distorted into an arc. The first two quadruply lensed candidates were reported in Ratnatunga et al 1995 (ApJL, 453, L5) We report on the subsequent eight candidates and describe them with simple models based on the assumption of singular isothermal potentials. Residuals from the simple models for some of the candidates indicate that a more complex model for the potential will probably be required to explain the full structural detail of the observations once they are confirmed to be lenses. We also discuss the effective survey area which was searched for these candidate lens objects.Comment: 26 pages including 12 figures and 10 tables. AJ Vol. 117, No.

COYOTES, SHEEP AND LITHIUM CHLORIDE

The use of LiCl-treated baits and carcasses has been advocated as a means of controlling coyote predation on sheep through a process known as aversive conditioning or taste aversion. While some investigators have made well publicized claims of damage reduction through the use of LiCl on sheep ranges, other researchers have experienced difficulty establishing prey aversion in captive coyotes. The conflicting results suggest a need for extensive, carefully controlled research in both pen and field situations before valid conclusions can be reached regarding aversive conditioning as a depredations control method

COYOTES, SHEEP AND LITHIUM CHLORIDE

The use of LiCl-treated baits and carcasses has been advocated as a means of controlling coyote predation on sheep through a process known as aversive conditioning or taste aversion. While some investigators have made well publicized claims of damage reduction through the use of LiCl on sheep ranges, other researchers have experienced difficulty establishing prey aversion in captive coyotes. The conflicting results suggest a need for extensive, carefully controlled research in both pen and field situations before valid conclusions can be reached regarding aversive conditioning as a depredations control method

The Morphologically Divided Redshift Distribution of Faint Galaxies

We have constructed a morphologically divided redshift distribution of faint field galaxies using a statistically unbiased sample of 196 galaxies brighter than I = 21.5 for which detailed morphological information (from the Hubble Space Telescope) as well as ground-based spectroscopic redshifts are available. Galaxies are classified into 3 rough morphological types according to their visual appearance (E/S0s, Spirals, Sdm/dE/Irr/Pec's), and redshift distributions are constructed for each type. The most striking feature is the abundance of low to moderate redshift Sdm/dE/Irr/Pec's at I < 19.5. This confirms that the faint end slope of the luminosity function (LF) is steep (alpha < -1.4) for these objects. We also find that Sdm/dE/Irr/Pec's are fairly abundant at moderate redshifts, and this can be explained by strong luminosity evolution. However, the normalization factor (or the number density) of the LF of Sdm/dE/Irr/Pec's is not much higher than that of the local LF of Sdm/dE/Irr/Pec's. Furthermore, as we go to fainter magnitudes, the abundance of moderate to high redshift Irr/Pec's increases considerably. This cannot be explained by strong luminosity evolution of the dwarf galaxy populations alone: these Irr/Pec's are probably the progenitors of present day ellipticals and spiral galaxies which are undergoing rapid star formation or merging with their neighbors. On the other hand, the redshift distributions of E/S0s and spirals are fairly consistent those expected from passive luminosity evolution, and are only in slight disagreement with the non-evolving model.Comment: 11 pages, 4 figures (published in ApJ

Compact Nuclei in Galaxies at Moderate Redshift:II. Their Nature and Implications for the AGN Luminosity Function

This study explores the space density and properties of active galaxies to z=0.8. We have investigated the frequency and nature of unresolved nuclei in galaxies at moderate redshift as indicators of nuclear activity such as Active Galactic Nuclei (AGN) or starbursts. Candidates are selected by fitting imaged galaxies with multi-component models using maximum likelihood estimate techniques to determine the best model fit. We select those galaxies requiring an unresolved point-source component in the galaxy nucleus, in addition to a disk and/or bulge component, to adequately model the galaxy light. We have searched 70 WFPC2 images primarily from the Medium Deep Survey for galaxies containing compact nuclei. In our survey of 1033 galaxies, the fraction containing an unresolved nuclear component greater than 5% of the total galaxy light is 9+/-1% corrected for incompleteness. In this second of two papers in this series, we discuss the nature of the compact nuclei and their hosts. We present the upper limit luminosity function (LF) for low-luminosity AGN (LLAGN) in two redshift bins to z=0.8. Mild number density evolution is detected for nuclei at -18 -16 and this flatness, combined with the increase in number density, is inconsistent with pure luminosity evolution. Based on the amount of density evolution observed for these objects, we find that almost all present-day spiral galaxies could have hosted a LLAGN at some point in their lives. We also comment on the likely contribution of these compact nuclei to the soft X-ray background.Comment: 50 pages, 14 figures, to appear in ApJ, April 199

Precision Fe Kalpha and Fe Kbeta Line Spectroscopy of the Seyfert 1.9 Galaxy NGC 2992 with Suzaku

We present detailed time-averaged X-ray spectroscopy in the 0.5--10 keV band of the Seyfert~1.9 galaxy NGC 2992 with the Suzaku X-ray Imaging Spectrometers (XIS). We model the complex continuum in detail. There is an Fe K line emission complex that we model with broad and narrow lines and we show that the intensities of the two components are decoupled at a confidence level >3sigma. The broad Fe K line has an EW of 118 (+32,-61) eV and could originate in an accretion disk (with inclination angle greater than ~30 degrees). The narrow Fe Kalpha line has an EW of 163 (+47,-26) eV and is unresolved FWHM <4090 km/s) and likely originates in distant matter. The absolute flux in the narrow line implies that the column density out of the line-of-sight could be much higher than measured in the line-of-sight, and that the mean (historically-averaged) continuum luminosity responsible for forming the line could be a factor of several higher than that measured from the data. We also detect the narrow Fe Kbeta line with a high signal-to-noise ratio and describe a new robust method to constrain the ionization state of Fe responsible for the Fe Kalpha and Fe Kbeta lines that does not require any knowledge of possible gravitational and Doppler energy shifts affecting the line energies. For the distant line-emitting matter (e.g. the putative obscuring torus) we deduce that the predominant ionization state is lower than Fe VIII (at 99% confidence), conservatively taking into account residual calibration uncertainties in the XIS energy scale and theoretical and experimental uncertainties in the Fe K fluorescent line energies. From the limits on a possible Compton-reflection continuum it is likely that the narrow Fe Kalpha and Fe Kbeta lines originate in a Compton-thin structure.Comment: Abstract is abridged. Accepted for publication in the Suzaku special issue of PASJ (November 2006). 18 pages, 6 figure