Dwain W. Warner

Relationships between Behavior, Physiology and Weather in Avian Transients at a Migration Stopover Site*

SummaryPopulations of avian transients were studied at a stopover area in southern Texas during four consecutive migration seasons, fall, 1973-spring, 1975. We captured individuals by mist net for banding and fat level determination. Concurrently we made observations on behavior of free-flying birds.We worked intensively with a single species, the Northern Waterthrush (Seiurus noveboracensis) while gathering weight fat and behavioral data on other species as well. Many of the patterns of weight change and behavior seen in the Northern Waterthrush were observed in other common passerines which occurred as transients on our study site.Results showed that birds in Zugstimmung and Zugdisposition differ, not only physiologically but behaviorally as well. Individuals of normally non-gregarious species that are in Zugstimmung are gregarious and stay in an area for only a short period. Their habitat needs are broad since these birds are not dependent on the food resources of the area in which they stop while in this physiological state. In contrast, normally non-gregarious migrants in Zugdisposition are hyperphagic and aggressively territorial in defense of resources and may stay at the same site for several days. Their habitat needs are quite specific since they must increase food intake by as much as 40% to build up fat reserves. Not all individuals in Zugdisposition are able to find territories at the same time. Those birds unable to claim territories either continue to migrate or stay in an area as floaters, continually attempting to obtain territories. Weather conditions probably act as a third variable that must be balanced by the individual in a complex optimization strategy with physiological state and success in competition.

BARRED OWL HABITAT USE AS DETERMINED BY RADIOTELEMETRY.

Radio transmitters were successfully placed on 10 barred owls (Strix varia) during 1965-66, and the movement of the owls were followed with an automatic radio-tracking system for a total of 1,182 days. More than 28,000 owl locations were sampled from some two million locations recorded. These locations, along with habitat availability information, were programmed for computer analysis to determine intensity of habitat use. Barred owls showed consistent and highly significant preference or avoidance for different habitats despite changing seasons, phenology, weather conditions, and years. The order of habitat preference in decreasing intensity of use uZas oak ( Quercus pp. ) woods, mixed hardwoods and conifers, white cedar (Thufa occidentalis) swamps, oak-savannas, alder (Alnus spp.) swamps, marshes, and open fields. This paper reports the use of radiotelemetry to determine the intensity of use of various habitat types by barred owls. The recently accelerated interest in predatory animals and the difficulties involved in the study of generally nocturnal and little known avian predators presented a dual challenge to the technique of radio-track-

Fall Daytime Resting Habits of Raccoons as Determined by Telemetry

The locations of 173 daytime resting sites of seven raccoons ( Procyon lotor ) in east central Minnesota were studied during September through November 1964. An automatic radio-tracking system was the mam method employed to locate animals, although field checks with a portable receiver also provided data. Persistent field checks apparently disturbed one of the animals. Distributions of resting sites of four of the animals are illustrated, described and analyzed; all individuals generally shifted resting sites from day to day, but each used certain areas more frequently than others. Ground beds in cattail marshes and alder and cedar swamps were used almost exclusively as resting sites. Some individuals shifted resting sites as much as one mile from one day to the next. No apparent patterns or consistencies among individuals were found in the frequency distributions of distances between consecutive resting sites or of activity radii of the sites. Evidence is presented indicating that three individuals using the same general area seemed to maintain a certain minimum distance among the resting sites chosen by each on any given day.

Movements and denning habits of a badger

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A Harness for Attaching Radio Transmitters to Large Owls

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. Association of Field Ornithologists and Blackwell Publishing are collaborating with JSTOR to digitize, preserve and extend access to Bird-Banding. by two rivets so the leather loops would not slip on the wire. This made the back strap 3 to 3 1/4 inches between neck and body loops. The back strap was essential for holding the transmitter in proper position as well as making it impossible for the owl to remove the harness. The battery was attached to the harness with string and transmitter parts were attached to one side of the battery and antenna with solder. Transmitter parts and battery were encapsulated in enough to withstand biting and clawing. The ingredients consisted of a liquid and a powder which could be mixed to any consistency. The transmitter was dipped into the mixture to cover all parts. A finger dipped into the liquid was used to smooth the acrylic over the transmitter. The acrylic has a working time of 5 minutes and a hardening time of about 30 minutes. Its reaction is exo-thermic, but the resulting temperature increase will not damage heat sensitive parts if no current is flowing through the transmitter. After the acrylic hardened, the transmitter was started by connecting two exposed wires and covering the connection with about three drops of acrylic. It transmitted 175 to 200 days using a Mallory ZM12 battery with a current drain of less than 1 mill-ampere and it had a maximum range of 3 miles. The harness and transmitter weighed about 70 grams but weight could be reduced for use on smaller owls by using a smaller battery although transmitter life would be shortened. [211 another person pulled a wing through each space located between the two loops and back strap. Care had to be taken in this procedure to avoid straining wing muscles. The neck loop was then slipped over the head and positioned on the lower part of the neck. In this position the transmitter was located near the front of the sternum with the back strap on the midline of the back between the wings (Figure 2). Captive Owls. Harnesses …

Territoriality and Population Structure in a Small Passerine Community1

An intensive study including banding, color marking and observations was performed in a small passerine community during the middle of the breeding season in northern Minnesota. Of 129 birds of 25 species banded, six individuals of five species possessed territories on the 0.64-ha study plot. For these five species, ratios of total males to ter- ritorial males varied from 4:1 to 16:1 and of males to females from 2.7:1 to 8.0:1. The meaning of these data in light of earlier work on territoriality is discussed, and it is concluded that current theories of ter- ritoriality are inadequate to explain these and similar data from other studies. Possible explanations for the patterns seen are given on the basis of the different selective pressures faced by mated and unmated males and females. The formulation of a meaningful concept of Type A terri- tory evolution and function must await a more complete understanding of the behavioral interrelationships of these four classes within this com- plex social system.

Decadal changes and delayed avian species losses due to deforestation in the northern Neotropics

How avifauna respond to the long-term loss and fragmentation of tropical forests is a critical issue in biodiversity management. We use data from over 30 years to gain insights into such changes in the northernmost Neotropical rainforest in the Sierra de Los Tuxtlas of southern Veracruz, Mexico. This region has been extensively deforested over the past half-century. The Estación de Biología Tropical Los Tuxtlas, of the Universidad Nacional Autónoma de México (UNAM), protects a 640 ha tract of lowland forest. It became relatively isolated from other forested tracts between 1975 and 1985, but it retains a corridor of forest to more extensive forests at higher elevations on Volcán San Martín. Most deforestation in this area occurred during the 1970s and early 1980s. Forest birds were sampled on the station and surrounding areas using mist nets during eight non-breeding seasons from 1973 to 2004 (though in some seasons netting extended into the local breeding season for some species). Our data suggested extirpations or declines in 12 species of birds subject to capture in mist nets. Six of the eight species no longer present were captured in 1992–95, but not in 2003–2004. Presence/absence data from netting and observational data suggested that another four low-density species also disappeared since sampling began. This indicates a substantial time lag between the loss of habitat and the apparent extirpation of these species. Delayed species loss and the heterogeneous nature of the species affected will be important factors in tropical forest management and conservation.