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We used radiotelemetry to investigate the spatial behavior of wintering Bicknell's Thrushes (Catharus bicknelli) at a mid-elevation rainforest site and a high-elevation cloud-forest site in the Dominican Republic. We also analyzed blood stable carbon isotopes and fecal samples to compare thrush diets at these two floristically and climatically distinct sites. Birds consumed a primarily fruit-based diet at the mid-elevation site and a primarily arthropod-based diet at the high-elevation site. Despite these dietary differences, individuals at both sites defended and maintained exclusive, minimally overlapping core use areas and home ranges. The mean size of both core use areas and home ranges was similar between males and females and between adults and first-winter birds. Presence of nonterritorial or 'floater' individuals was low at both sites (2.7% and 5.6%). Birds at the arthropod-dominated site were observed significantly more often on or within i m of the ground than birds at the fruit-heavy site, which were more often observed in the mid-canopy structure above 2 m. Birds at both sites displayed agonistic behaviors toward conspecifics and toward playback of conspecific vocalizations. Exclusive territoriality was the predominant winter social system, and we suggest that both arthropods and fruit are defensible resources for wintering Bicknell's Thrushes. Received 31 August 2009, accepted 13 January 2010. Key words: Bicknell's Thrush, Catharus bicknelli, Nearctic--Neotropical migrant, nonbreeding diet, radiotelemetry, winter social system. Utilizamos radiotelemetria para investigar el comportamiento espacial de individuos invernantes de la especie Catharus bicknelli en un bosque humedo ubicado a elevaciones medias y en un bosque nublado de alta elevacion en la Republica Dominicana. Tambien analizamos isotopos estables de carbono en la sangre y muestras fecales para comparar la dieta de las aves entre estos dos sitios, que son florisitica y climaticamente distintos. Las aves consumieron una dieta principalmente basada en frutos en el sitio de elevaciones medias y una principalmente basada en artropodos en el de elevaciones altas. A pesar de esas diferencias dietarias, los individuos de ambos sitios defendieron y mantuvieron areas nucleares de uso y ambitos hogarefios exclusivos, con minima superposicion. El tamano medio de tanto las areas nucleares de uso como de los ambitos hogarenos fue similiar entre machos y hembras, y entre adultos y aves en su primer invierno. La presencia de individuos no territoriales o 'flotantes' fue baja en ambos sitios (2.7% y 5.6%). Las aves del sitio dominado por artropodos se observaron con una frecuencia significativamente mayor en el suelo o a 1 m de este que las aves del sitio dominado por frutas, las cuales se observaron con mayor frecuencia en la estructura del dosel medio por encima de 2 m. Las aves de ambos sitios exhibieron comportamientos agresivos ante individuos coespecificos y ante la reproduccion de vocalizaciones coespecificas grabadas previamente. La territorialidad exclusiva fue el sistema social predominante del invierno y sugerimos que tanto los artropodos como las frutas son recursos defendibles por parte de los individuos invernantes de C. bicknelli. DOI: 10.1525/auk.2010.09160

We used radiotelemetry to evaluate at-sea habitat use by Cassin's Auklets (Ptychoramphus aleuticus) that bred at Prince Island, off southern California, from 1999 through 2001. We used logistic regression to compare paired radiotelemetry (presence) with random (pseudo-absence) location-associated habitat variables derived from (1) satellite remote-sensing of sea surface temperature and chlorophyll-a concentration and (2) bathymetry. Compared with random locations within their foraging area and after controlling for distance to colony, odds ratios indicated that Cassin's Auklets with dependent young occurred in relatively shallower, warmer, and chlorophyll-rich water associated with chlorophyll fronts near the insular shelf break. These oceanographic features characterize habitats that support key euphausiid prey (e.g., Thysanoessa spinifera) and also other krill predators. Radiotelemetry combined with satellite remote-sensing of the ocean provides an alternative to vessel-based surveys for evaluating seabird foraging habitats. In the absence of information on the actual distribution, abundance, and, hence, availability of zooplankton prey for seabirds, environmental factors can serve as proxies to help elucidate distributional patterns of seabirds at sea. Received 10 September 2008, accepted 27 December 2009. Key words: California Bight, California Current, Cassin's Auklet, logistic regression, Ptychorarnphus aleuticus, radiotelemetry, southern seabird foraging habitat. Utilizamos radiotelemetria para evaluar el uso de habitat marino de individuos de Ptychoramphus aleuticus que anidan en la isla Prince, en el sur de California entre los anos 1999 y 2001. Usamos regresion logistica para comparar las localizaciones de habitat de forrajeo obtenidas con telemetria (presencias) con puntos escogidos al azar (pseudo-ausencias) asociadas a tres variables medioambientales obtenidas a partir de imagenes satelitales, concentracion de clorofila-a y temperatura de superficie, y de datos de batimetria. Despues de controlar por el efecto de la distancia a la colonia, el analisis revelo que los individuos de P. aleuticus con crias ocupaban las aguas menos profundas, mas calientes y con concentraciones de cloronla mas altas. Estas caracteristicas, que identifican las zonas de frentes oceanograficos al borde de la plataforma peri-insular, tembien definen los habitats de los eufausidos que son presas clave (e.g., Thysanoessa spinifera) y de otros depredadores de krill. En comparacion con los metodos de muestreo que utilizan embarcaciones, el uso conjunto de radiotelemetria con datos obtenidos de imagenes satelitales proporciono una forma alternativa para el estudio los habitats de forrajeo de las aves marinas. Este metodo es especialmente util en situaciones donde la falta de informacion sobre la distribucion y abundancia del zooplancton imposibilita la evaluacion de la disponibilidad de recursos para las aves marinas. En estos casos, el uso de variables medioambientales obtenidas indirectamente a traves de imagenes satelitales puede facilitar el estudio de la distribucion de las aves en el mar. DOI: 10.1525/auk.2010.09273

Recent studies have applied state space models to satellite telemetry data in order to remove noise from raw location estimates and infer the true tracks of animals. However, while the resulting tracks may appear plausible, it is difficult to determine the accuracy of the estimated positions, especially for position estimates interpolated to times between satellite locations. In this study, we use data from two gray seals (Halichoerus grypus) carrying tags that transmitted Fastloc GPS positions via Argos satellites. This combination of Service Argos data and highly accurate GPS data allowed examination of the accuracy of state--space position estimates and their uncertainty derived from satellite telemetry data. After applying a speed filter to remove aberrant satellite telemetry locations, we fit a continuous-time Kalman filter to estimate the parameters of a random walk, used Kalman smoothing to infer positions at the times of the GPS measurements, and then compared the filtered telemetry estimates with the actual GPS measurements. We investigated the effect of varying maximum speed thresholds in the speed-filtering algorithm on the root mean-square error (RMSE) estimates and used minimum RMSE as a criterion to guide the final choice of speed threshold. The optimal speed thresholds differed between the two animals (1.1 m/s and 2.5 m/s) and retained 50% and 65% of the data for each seal. However, using a speed filter of 1.1 m/s resulted in very similar RMSE for both animals. For the two seals, the RMSE of the Kalman-filtered estimates of location were 5.9 and 12.76 kin, respectively, and 75% of the modeled positions had errors less than 6.25 km and 11.7 km for each seal. Confidence interval coverage was close to correct at typical levels (80-95%), although it tended to be overly generous at smaller sizes. The reliability of uncertainty estimates was also affected by the chosen speed threshold. The combination of speed and Kalman filtering allows for effective calculation of location and also indicates the limits of accuracy when correcting service Argos locations and linking satellite telemetry data to spatial covariate and habitat data. Key words: Argos error; Fastloc GPS; gray seal; Halichoerus grypus; Kalman filter; marine mammals; state--space model.

A multipath propagation model for aeronautical telemetry over water at 8.0 GHz is presented. Data recorded during channel sounding experiments, conducted over the Pacific Ocean near Point Mugu, CA was used to model the multipath propagation. The modeling results show that a three-ray model consisting of line-of-sight propagation and two reflected propagation paths is a good fit for the measured channel frequency responses. One of the reflected propagation paths is a strong specular reflection determined by the geometry defined by the airborne transmitter, the ground-based receiver, and the sea surface. For the flight profiles used, the delay of this path is between 10 and 50 ns. The other propagation path is a more diffuse, random reflection whose amplitude is significantly smaller than the amplitude of the specular reflection and whose mean excess delay is 57 ns with an rms delay spread of 25 ns.

The use of analog circuits to reduce the size and power consumption of channel decoders such as Viterbi decoders has been an active area of research over the recent years. However, the need for digital memory to store the history of the path elimination decisions in a Viterbi decoder, limits the potential advantages that could be offered by an all-analog convolutional decoder implementation. This is especially so in cases where the use of an older silicon process technology is dictated by the application; hence, the power-reduction benefits offered by deep sub-micrometer digital designs cannot be exploited. A novel alternative convolutional decoding method which allows for an entirely analog implementation is the modified feedback decoding algorithm (MFDA). This paper describes the first integrated realization of a convolutional decoder employing the MFDA. The rate-1/2, constraint-length-3 decoder, employs a current-mode analog signal processing core and was fabricated in a 0.6-[micro]m CMOS process technology, occupying an area of 0.5 [mm.sup.2]. Measured results show that decoding speeds in excess of 1-Mb/s are possible with virtually no loss in coding gain. Total power consumption is 2.45 mW from a single 3-V supply. Although a hard-decision decoder, conversion to soft-decision decoding requires only the inclusion of a simple analog delay line as shown in the paper. The decoder is dedicated to an implantable biotelemetry system, but it can also find use in other low-power applications. System-level coding simulations are also presented which are useful for the construction of larger decoders where the benefits of the MFDA approach would be more pronounced. Index Terms--Analog decoder, convolutional codes, current-mode circuits, implanted devices, modified feedback decoding algorithm (MFDA), telemetry, Viterbi decoder.

The fragmentation of forests by the expansion of agriculture is recognized as an important factor influencing worldwide declines of forest-dependent species. Species that are forest dependent may be especially vulnerable to fragmentation because they have specialized resource requirements and may exhibit lower mobility in an agricultural matrix. We investigated movement patterns and resource selection of forest-dependent northern long-eared myotis (Myotis septentrionalis) in a forest-agricultural landscape on Prince Edward Island, Canada. Radiotelemetry was used to locate day-roosts and to estimate locations of female bats during nightly foraging bouts. Day-roost locations and foraging areas were mapped using a geographic information system to generally characterize the forest cover of foraging and roosting areas. Vegetative structure and insect prey availability were measured in the field and compared between foraging and roosting areas to describe resource selection at these sites. Movements of female northern long-eared myotis were constrained to forest features and foraging areas were concentrated along forest-covered creeks with bats roosting predominantly in deciduous trees within the same forest fragment, although bats at 1 site seemed to exclusively use a barn during late pregnancy and lactation. Differences in prey availability did not explain the spatial segregation of roosting and foraging areas. Relative to roost areas foraging sites were more likely to be close to forested creeks and densely forested areas, whereas roost sites were characterized by the availability of potentially suitable roosts. This study demonstrates the importance of investigating movements and resource selection of individuals in fragmented landscapes because a specialization on forest resources can highly restrict the vagility of forest-dependent species to a local environment. Key words: Chiroptera, forest fragmentation, forest structure, Prince Edward Island, radiotelemetry, roost trees

This paper presents a production-oriented chip-set to be used as the circuitry needed to implement the necessary RF functionalities of a new generation of S-band satellite transponders for telemetry tacking and control (TT&C) applications. The RF hardware section integration is achieved by means of a customized chip-set of just four multi-chip multifunction MMIC (MCMM) modules. The functions contained in the monolithic microwave integrated circuits (MMICs) include the active circuits needed for the front-end low noise amplifier (LNA), the RF and IF converters, all the variable gain amplifiers (VGAs), the Voltage Controlled Oscillatar (VCO) for both transmit and receive sections, the frequency prescaler and multiplier needed to synthesize the frequency plan as well as the Local Oscillatar (LO) amplifiers. The selected technology is GaAs, mainly due to its radiation hardness, essential for aerospace applications, and good reliability. Issues such as suitable circuit topology, efficient dc biasing, circuit area minimization, cost-oriented system design and advanced packaging techniques have been addressed during the design. Measurements and yield results from the manufactured circuits will be presented showing that these components, even though especially designed in the frame of the GALILEO TT&C transponder predevelopment, are suitable for a variety of missions, from Deep space to near Earth, including spread-spectrum transponders with precision ranging function.

This paper describes a preliminary experimental investigation to convey acceleration measurements, made on-board an electromagnetic (EM) launched projectile, using microwave telemetry techniques. The focus of the investigation is to extend the Hardened Subminiature Telemetry and Sensor Systems (HSTSS) technology for use in EM launch environments. Many aspects of the HSTSS technology have already been successfully demonstrated in high-G, high-pressure launch environments in conventional gun systems. In addition, microwave transmission in stationary experiments, where the telemetry package was exposed to relatively high magnetic fields and EM transients in a railgun launcher, has been demonstrated. However, microwave telemetry during an EM launch has not been demonstrated until now. In this work, setback acceleration measurements obtained with an on-board accelerometer were processed by HSTSS electronics and transmitted simultaneously during launch via an antenna located in front of the EM launch package. While only the test conducted at 9-kG peak acceleration provided the most useful data, detailed analyses suggest that mechanical problems--rather than the microwave telemetry process itself--were probably responsible for difficulties experienced at higher accelerations. This paper reviews the experimental methodology and discusses the results of the investigation. Index Terms--Accelerometer, FM, hardened, RF, S-band.

Issues relating to the use of radiotelemetry when studying animal behaviour patterns are discussed. A former study looked at the use of capture patches for lynx. The effects of the capture event on subsequent movement patterns are studied.

Researchers examined the effects of two different methods of attaching radio transmitters to mallards, as some experts have expressed concern that the use of abdominal implants affects wildfowl behaviour and survival. The researchers compared the use of transmitters attached to the backs of birds against abdominally implanted transmitters. The results indicated that the back-anchored packages may have had a negative impact on reproduction and, at one of the five sites, the females with backpacks had a significantly higher mortality rate than those with abdominal implants.

I studied survival of 100 radio-tagged gray partridge (Perdix perdix) in North Dakota from winter to the beginning of nesting during 1985-87. Radio transmitters appeared to cause significant mortality among captured partridge (34%) during the first week postrelease, after accounting for mortality expected from other sources. Survival of partridge living >7 days posttrapping (n = 55) from early January to 1 May was 38%. The major source of mortality after the first week was raptor predation. A Cox's proportional hazards analysis revealed that body mass (P = 0.003) and sex (P = 0.04) were significantly related to probability of survival. Partridge weighing [is greater than or equal to]400 g had higher survival (50%) than those weighing

Sixty-nine radio-telemetry papers published from 1986-92 were reviewed to determine the extent to which authors employed and reported error measures for radio telemetry data. Results showed that there is inadequate use and reportiing of error measures, which could lead to misinterpretation of data. The importance of estimating and reporting the precision of radio tracking data is reiterated.

We assessed 3 methods of estimating daily activity patterns in the Egyptian mongoose (Herpestes ichneumon): net activity time (M1), percentage of localizations with activity (M2), and distance traveled (M3). The 3 methods gave similar results ([r.sub.s] > 0.89, P < 0.0001). With M1 and M2 7 days of tracking were necessary for obtaining a consistent activity pattern ([r.sub.s] = 0.91), whereas 15 days were required for M3 ([r.sub.s] = 0.80).