6,997 research outputs found
The Institute for Raptor Studies Expeditions in Mongolia, 1994-2000
In 1994, 1995, 1997, 1998, and 2000, I led small teams of biologists across Mongolia in search of Saker falcon (Falco cherrug Gray) and golden eagle (Aquila chrysaetos) eyries. We also counted raptors along our march route during the first three years. These expeditions documented: (1) occupancy and productivity rates, and described eyrie sites, for Saker falcons (150 territories, 182 eyries) and golden eagles (27 known breeding territories), (2) mortality of Sakers and ipland buzzards (Buteo hemilasius) due to entanglement with trash in nests and loss of golden eagle eggs due to concealment by trash in nests, (3) long-distance movements of an adult steppe eagle (Aquila nipalensis) and one young monk vulture (Aegypius monachus) via satellite telemetry, (4) occurrence of gyrfalcon-like Sakers at many locations across Mongolia, (5) extensive variation in leg and foot feathering in the upland buzzard that probably is evidence that this species is the result of hybridization, (6) extensive use by Sakers of powerline support structures for nesting (7) Saker ground nesting, nesting on boulders, in attics, on buildings, and on many other novel supports, (8) use of paper money in golden eagle and upland buzzard nests as nesting materials, (9) the first observation of siblicide for falcons (Sakers) and a new falcon social display (splayed-toes-flight), also for the Saker, (10) extensive predation on mammalian and avian predators by the Golden Eagle, (11) breeding by pale steppe eagles, and (12) relatedness of Mongolian Sakers to other Saker and gyrfalcon (Falco rusticolus) demes. In response to the propensity of Mongolian Sakers to nest on artificial structures, and from an apparent population limiting lack of suitable breeding sites, we began in 1997 to create artificial eyries for Sakers, with 150 built by 2000
The Institute for Raptor Studies Expeditions in Mongolia, 1994-2000
In 1994, 1995, 1997, 1998, and 2000, I led small teams of biologists across Mongolia in search of Saker falcon (Falco cherrug Gray) and golden eagle (Aquila chrysaetos) eyries. We also counted raptors along our march route during the first three years. These expeditions documented: (1) occupancy and productivity rates, and described eyrie sites, for Saker falcons (150 territories, 182 eyries) and golden eagles (27 known breeding territories), (2) mortality of Sakers and ipland buzzards (Buteo hemilasius) due to entanglement with trash in nests and loss of golden eagle eggs due to concealment by trash in nests, (3) long-distance movements of an adult steppe eagle (Aquila nipalensis) and one young monk vulture (Aegypius monachus) via satellite telemetry, (4) occurrence of gyrfalcon-like Sakers at many locations across Mongolia, (5) extensive variation in leg and foot feathering in the upland buzzard that probably is evidence that this species is the result of hybridization, (6) extensive use by Sakers of powerline support structures for nesting (7) Saker ground nesting, nesting on boulders, in attics, on buildings, and on many other novel supports, (8) use of paper money in golden eagle and upland buzzard nests as nesting materials, (9) the first observation of siblicide for falcons (Sakers) and a new falcon social display (splayed-toes-flight), also for the Saker, (10) extensive predation on mammalian and avian predators by the Golden Eagle, (11) breeding by pale steppe eagles, and (12) relatedness of Mongolian Sakers to other Saker and gyrfalcon (Falco rusticolus) demes. In response to the propensity of Mongolian Sakers to nest on artificial structures, and from an apparent population limiting lack of suitable breeding sites, we began in 1997 to create artificial eyries for Sakers, with 150 built by 2000
Advanced materials for space nuclear power systems
The overall philosophy of the research was to develop and characterize new high temperature power conversion and radiator materials and to provide spacecraft designers with material selection options and design information. Research on three candidate materials (carbide strengthened niobium alloy PWC-11 for fuel cladding, graphite fiber reinforced copper matrix composites for heat rejection fins, and tungsten fiber reinforced niobium matrix composites for fuel containment and structural supports considered for space power system applications is discussed. Each of these types of materials offers unique advantages for space power applications
WHOOPING CRANE EGG MANAGEMENT: OPTIONS AND CONSEQUENCES
Eggs to build captive whooping crane (Grus americana) flocks and most eggs for reintroduction experiments have come from second viable eggs in 2-egg clutches in Canada. Four years ago, egg removal ceased. Based on reproductive rates for years when second eggs were removed and for years when eggs were not removed, we project numbers of young fledging in the wild and in captivity for the 2 most likely egg-management strategies. From existing data sets, we find that reproductive performance was, on average, better during the era of routine removal of the second viable eggs than when no manipulation occurred. Further, the munber of young produced in captivity from the removed eggs, on average, resulted in a doubling of the number of young birds (wild and captive) alive each autumn
Comments on gauge-invariance in cosmology
We revisit the gauge issue in cosmological perturbation theory, and highlight
its relation to the notion of covariance in general relativity. We also discuss
the similarities and differences of the covariant approach in perturbation
theory to the Bardeen or metric approach in a non-technical fashion.Comment: 7 pages, 1 figure, revtex4; v3: minor changes, typos corrected,
discussion extended; v4: typos corrected, corresponding to published versio
Estimating the active space of male koala bellows: propagation of cues to size and identity in a Eucalyptus forest
Examining how increasing distance affects the information content of vocal signals is fundamental for determining the active space of a given species’ vocal communication system. In the current study we played back male koala bellows in a Eucalyptus forest to determine the extent that individual classification of male koala bellows becomes less accurate over distance, and also to quantify how individually distinctive acoustic features of bellows and size-related information degrade over distance. Our results show that the formant frequencies of bellows derived from Linear Predictive Coding can be used to classify calls to male koalas over distances of 1–50 m. Further analysis revealed that the upper formant frequencies and formant frequency spacing were the most stable acoustic features of male bellows as they propagated through the Eucalyptus canopy. Taken together these findings suggest that koalas could recognise known individuals at distances of up to 50 m and indicate that they should attend to variation in the upper formant frequencies and formant frequency spacing when assessing the identity of callers. Furthermore, since the formant frequency spacing is also a cue to male body size in this species and its variation over distance remained very low compared to documented inter-individual variation, we suggest that male koalas would still be reliably classified as small, medium or large by receivers at distances of up to 150 m
RESULTS OF AN EXPERIMENT TO LEAD CRANES ON MIGRATION BEHIND MOTORIZED GROUND VEHICLES
Ten greater sandhill cranes (Grus canadensis tabida) , trained to enter and ride in a specially-equipped truck, were transported at ca 80 days of age from their rearing site at Patuxent Wildlife Research Center (patuxent), Maryland, to a reintroduction site located within the species\u27 former breeding range in northern Arizona. After 5 additional weeks of training, these juvenile cranes were led south ca 600 km to a wintering area on the Arizona/Mexico border. Nine of the 10 survived the trek, 495 km of which were flown, although only a few cranes flew every stage of the route. Their longest flight was 77 lan. Major problems during the migration were powerline collisions (3, 1 fatal), eagle attacks (none fatal), and overheating (when air temperatures exceeded ca 25 C). All cranes that entered training quickly learned to follow the truck, and their tenacity when following under unfavorable conditions (e.g., poor light, extreme dust, or heat) showed that cranes could consistently be led over long distances. We cannot predict if the cranes will retrace their route unassisted when adults, but 2 cranes returned 130 km to the starting point of the migration after the flock was scattered by an eagle during our migration south. Three other cranes were recovered 55 km from the attack site and on course toward the starting point
RESULTS OF AN EXPERIMENT TO LEAD CRANES ON MIGRATION BEHIND MOTORIZED GROUND VEHICLES
Ten greater sandhill cranes (Grus canadensis tabida) , trained to enter and ride in a specially-equipped truck, were transported at ca 80 days of age from their rearing site at Patuxent Wildlife Research Center (patuxent), Maryland, to a reintroduction site located within the species\u27 former breeding range in northern Arizona. After 5 additional weeks of training, these juvenile cranes were led south ca 600 km to a wintering area on the Arizona/Mexico border. Nine of the 10 survived the trek, 495 km of which were flown, although only a few cranes flew every stage of the route. Their longest flight was 77 lan. Major problems during the migration were powerline collisions (3, 1 fatal), eagle attacks (none fatal), and overheating (when air temperatures exceeded ca 25 C). All cranes that entered training quickly learned to follow the truck, and their tenacity when following under unfavorable conditions (e.g., poor light, extreme dust, or heat) showed that cranes could consistently be led over long distances. We cannot predict if the cranes will retrace their route unassisted when adults, but 2 cranes returned 130 km to the starting point of the migration after the flock was scattered by an eagle during our migration south. Three other cranes were recovered 55 km from the attack site and on course toward the starting point
Non-Critical Liouville String Escapes Constraints on Generic Models of Quantum Gravity
It has recently been pointed out that generic models of quantum gravity must
contend with severe phenomenological constraints imposed by gravitational
Cerenkov radiation, neutrino oscillations and the cosmic microwave background
radiation. We show how the non-critical Liouville-string model of quantum
gravity we have proposed escapes these constraints. It gives energetic
particles subluminal velocities, obviating the danger of gravitational Cerenkov
radiation. The effect on neutrino propagation is naturally flavour-independent,
obviating any impact on oscillation phenomenology. Deviations from the expected
black-body spectrum and the effects of time delays and stochastic fluctuations
in the propagation of cosmic microwave background photons are negligible, as
are their effects on observable spectral lines from high-redshift astrophysical
objects.Comment: 15 pages LaTeX, 2 eps figures include
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