THE MIGRATION PATTERNS OF THE PURPLE SANDPIPER CALIDRIS MARITIMA

Summers, R. W. 1994. The migration patterns of the Purple Sandpiper Calidris maritima. Ostrich 65: 167–173.

The Purple Sandpiper breeds largely in the Arctic, and winters (boreal season) on the rocky shores of the north Atlantic, further north than any other sandpiper. As the populations from Canada, Greenland, Iceland, Svalbard, Norway and Russia differ in wing and bill lengths it is possible to match measurements taken from breeding birds with samples of birds caught in winter. Ringing recoveries, especially from colour marked birds, have also helped to determine migration routes and wintering areas. Four populations move to the nearest ice-free coast. Two populations move south of the nearest ice-free coast, being replaced by larger birds from a more northerly population (“chain migration”). Only the north Canadian population is believed to migrate a long distance, “leap-frogging” other winter populations. These patterns are discussed in relation to theories for the migration patterns of waders.     

Contrasting behavior between two populations of an ice‐obligate predator in East Antarctica

The Austral autumn–winter is a critical period for capital breeders such as Weddell seals that must optimize resource acquisition and storage to provision breeding in the subsequent spring. However, how Weddell seals find food in the winter months remains poorly documented. We equipped adult Weddell seals after their annual molt with satellite‐relayed data loggers at two sites in East Antarctica: Dumont D'Urville (n = 12, DDU) and Davis (n = 20). We used binomial generalized mixed‐effect models to investigate Weddell seals’ behavioral response (i.e., “hunting” vs. “transit”) to physical aspects of their environment (e.g., ice concentration). Weddell seal foraging was concentrated to within 5 km of a breathing hole, and they appear to move between holes as local food is depleted. There were regional differences in behavior so that seals at Davis traveled greater distances (three times more) and spent less time in hunting mode (half the time) than seals at DDU. Despite these differences, hunting dives at both locations were pelagic, concentrated in areas of high ice concentration, and over areas of complex bathymetry. There was also a seasonal change in diving behavior from transiting early in the season to more hunting during winter. Our observations suggest that Weddell seal foraging behavior is plastic and that they respond behaviorally to changes in their environment to maximize food acquisition and storage. Such plasticity is a hallmark of animals that live in very dynamic environments such as the high Antarctic where resources are unpredictable.     

The annual cycle of wing-moult and breeding in the Wattled Starling Creatophora cinerea

Moult, breeding and seasonal occurrence of the Wattled Starling Creatophora cinerea throughout its range in Africa are reviewed based on data from museum specimens and the published literature. Neither moult nor breeding follows a rigid seasonal pattern, although there are some regional differences, and overlap between moult and breeding is unlikely. The regular occurrence of interrupted wing-moult may be associated with nomadic movements rather than opportunistic breeding.     

Territory surveillance and prey management: Wolves keep track of space and time

Identifying behavioral mechanisms that underlie observed movement patterns is difficult when animals employ sophisticated cognitive‐based strategies. Such strategies may arise when timing of return visits is important, for instance to allow for resource renewal or territorial patrolling. We fitted spatially explicit random‐walk models to GPS movement data of six wolves (Canis lupus; Linnaeus, 1758) from Alberta, Canada to investigate the importance of the following: (1) territorial surveillance likely related to renewal of scent marks along territorial edges, to reduce intraspecific risk among packs, and (2) delay in return to recently hunted areas, which may be related to anti‐predator responses of prey under varying prey densities. The movement models incorporated the spatiotemporal variable “time since last visit,” which acts as a wolf's memory index of its travel history and is integrated into the movement decision along with its position in relation to territory boundaries and information on local prey densities. We used a model selection framework to test hypotheses about the combined importance of these variables in wolf movement strategies. Time‐dependent movement for territory surveillance was supported by all wolf movement tracks. Wolves generally avoided territory edges, but this avoidance was reduced as time since last visit increased. Time‐dependent prey management was weak except in one wolf. This wolf selected locations with longer time since last visit and lower prey density, which led to a longer delay in revisiting high prey density sites. Our study shows that we can use spatially explicit random walks to identify behavioral strategies that merge environmental information and explicit spatiotemporal information on past movements (i.e., “when” and “where”) to make movement decisions. The approach allows us to better understand cognition‐based movement in relation to dynamic environments and resources.     

Very low pressures drive ventilatory flow in chimaeroid fishes

Chimaera (Holocephali) are cartilaginous fishes with flexible operculi rather than external gill slits, suggesting ventilation occurs in a manner different from other fishes. We examined holocephalan ventilation morphology, behavior, and performance by anatomical investigations, high‐speed video, and in vivo pressure measurements from the buccal and parabranchial cranial cavities in Hydrolagus colliei and Callorhinchus callorynchus. Ventilatory modes ranged from quiet resting breathing to rapid “active” breathing, yet external cranial movements—excepting the passive movement of the opercular flap—were always extremely subtle, and pressures generated were one to two orders of magnitude lower than those of other fishes. To explain ventilation with such minimal pressure generation and cranial motion, we propose an “accordion” model, whereby rostrocaudal movement of the visceral arches drives pressure differentials, albeit with little lateral or ventral movement. Chimaeroids have comparatively large oropharyngeal cavities, which can move fluid with a smaller linear dimension change than the comparatively smaller cavities of other fishes. Orobranchial pressures are often less than parabranchial pressures, suggesting flow in the “wrong” direction; however, the long gill curtains of chimaeroids may passively restrict backflow. We suggest that constraints on holocephalan jaw and hyoid movements were compensated for evolutionarily by novel visceral arch mechanics and kinematics. J. Morphol., 2012. © 2011 Wiley Periodicals, Inc.     

What drives fine‐scale movements of large herbivores? A case study using moose

Understanding animal movements across heterogeneous landscapes is of great interest because it helps explain the dynamic processes influencing the distribution of individuals in space. Research on how animals move relative to short‐range environmental characteristics are scarce. Our objective was to determine the variables influencing movement of a large ungulate, the moose Alces alces, ranging across a boreal landscape, and to link movement behaviour with limiting factors at a fine scale. We assessed 7 candidate models composed of vegetation, solar energy, and topography variables using step selection functions (SSF) for male and female moose across daily and annual periods. We selected and weighted models using the Bayesian Information Criterion. Variables influencing small‐scale movements of moose differed among periods and between sexes, likely in response to corresponding changes in the importance of limiting factors. Best models often combined many types of variables, although simpler models composed of only vegetation or topography variables explained male's movements during rut and early winter. Moose steps were observed in good feeding stands from summer to early winter for females and from spring to early winter for males, supporting other studies of moose habitat selection. From summer to early winter, females alternatively selected and avoided cover stands during day and night, respectively. Solar energy reaching the ground was important, particularly during late winter and spring, likely due to its effect on snow cover, air temperature, or plant phenology. Moose generally moved in gentle slopes and variable elevation, which may have increased their chances of finding high quality forage, or improved their search of suitable calving sites or mates. Our study revealed the great complexity and dynamic aspects of animal movements in a heterogeneous landscape. Analysis of animal movement provides complementary information to more static habitat selection analyses and helps understanding the spatial variations in the distribution of individuals through time.     

Movements of wintering Dunlin Calidris alpina and changing habitat availability in an agricultural wetland landscape

Few studies have assessed how the dynamics of wetland bird movements relate to changing resource availability, particularly at more than one spatial scale. Within western Oregon's Williamette Valley, we examined winter resident Dunlin Calidris alpina movements in relation to a decrease in availability of preferred shorebird foraging habitat from early to late winter of 1999–2000. By tracking movements of 15 (early winter) and 12 (late winter) radiomarked individuals, we calculated home ranges and characterized presence/absence of a preference for shorebird foraging habitat during each winter period. Between periods, we compared: (1) percentage of shorebird habitat in home ranges to its availability in the landscape (regional preference), (2) percentage of radio locations in shorebird habitat to its availability within home ranges (local preference) and (3) relative use of roost sites. Concurrent with a 75% decrease in available shorebird habitat from early to late winter, average home range sizes increased by a factor of 3.8. At a regional scale, home ranges in early winter included a significantly greater percentage of shorebird foraging habitat than was available in the wider landscape. However, by late winter, the percent of shorebird habitat in home ranges did not match availability in the landscape. At the local scale, for both winter periods Dunlin were located in shorebird foraging habitat more often than expected given availability of habitat within home ranges [Correction added after online pub-lication 23 May 2008: sentence amended]. An increase in the number of roosts used from early to late winter implies possible reliance on additional sites in late winter for foraging opportunities. Results suggest that wet, unvegetated habitat is sought by Dunlin throughout winter, but individuals could not select home ranges in late winter that fully compensated for seasonal loss of habitat.     

A Causal Analysis of Observed Declines in Managed Honey Bees (Apis mellifera)

The European honey bee (Apis mellifera) is a highly valuable, semi-free-ranging managed agricultural species. While the number of managed hives has been increasing, declines in overwinter survival, and the onset of colony collapse disorder in 2006, precipitated a large amount of research on bees’ health in an effort to isolate the causative factors. A workshop was convened during which bee experts were introduced to a formal causal analysis approach to compare 39 candidate causes against specified criteria to evaluate their relationship to the reduced overwinter survivability observed since 2006 of commercial bees used in the California almond industry. Candidate causes were categorized as probable, possible, or unlikely; several candidate causes were categorized as indeterminate due to lack of information. Due to time limitations, a full causal analysis was not completed at the workshop. In this article, examples are provided to illustrate the process and provide preliminary findings, using three candidate causes. Varroa mites plus viruses were judged to be a “probable cause” of the reduced survival, while nutrient deficiency was judged to be a “possible cause.” Neonicotinoid pesticides were judged to be “unlikely” as the sole cause of this reduced survival, although they could possibly be a contributing factor.     

Dynamique et èvolution de l'herbier à Posidonia oceanica en Méditerranée

Abstract

The natural growth of a Posidonia oceanica meadow is the result of a long process of development (series of events), but the dynamics are often difficult to establish because of the lack of a zero state and of sufficiently long chronological series. In addition, while it is sometimes possible to observe major regressions, the phenomena of recolonisation and of small-scale fluctuations are rarely detected. Nevertheless, with the emergence of new investigatory techniques (lepidochronology, microcartography, monitoring networks, accurate dating techniques, etc.,) considerable progress has been made in this field. The development in space and time of the seagrass beds is dependant on hydrodynamic action and sedimentary deposits. This means that in sheltered bays Posidonia oceanica may form original structures such as barrier reefs or micro-atolls, while in turbulent waters one observes the formation of spectacular structures resulting from erosion (intermatte, “rivière de retour”). A disequilibrium in sedimentation may result in dramatic regression in some seagrass beds. The multiplicity of prevailing environmental conditions results in the occurrence of a range of meadow types: “herbiers de plaines”, “herbiers de collines”, “herbiers tigrés”, “herbiers en escalier”. The impact of human pressure over the past few decades has not been insignificant. Coastal development constructions that have altered the direction of currents and the sedimentation, sewage outfalls that have resulted in an increase in the turbidity of the water and the mechanical action of anchors or trawl nets which have damaged certain areas of seagrass meadow have caused extensive regression. Conversely, the rehabilitation of previously degraded areas has made it possible to monitor the process of recolonisation.     

The Role of “Outward-Journey Information” in Homing Experiments with Pigeons: New Data on Ontogeny of Navigation and General Survey

Potentially, homing from distant areas can be based on two different principles of navigation: (1) A path-integration mechanism records and integrates an animal's motions during the outward trip; it is independent of location-specific stimuli. (2) Site localization, by contrast, is performed by deducing the animal's position in relation to home from such stimuli. Hence the first mechanism entirely depends on an uninterrupted flow of “outward-journey information”. The second mechanism may but need not be independent of stimuli recorded during the outward journey. Homing of pigeons is evidently based on site localization. Empirical findings do not support the idea that in experiments using passive displacement path integration is involved in addition or alternatively. Also, there is no reason to assume that very young pigeons transitionally, for only few weeks, apply such a method (as has been concluded by Wiltschko & Wiltschko 1982, 1985, etc.). It is shown that very young pigeons require local olfactory signals for initial homeward orientation as do older birds (Fig. 1). They are not generally better at homeward orientation than older inexperienced pigeons and show similar deviations from home and preferences for a particular compass direction (Table 1, Fig. 2). Olfactory signals appear to be gathered, as good as conditions allow, during any stage of a homing experiment. No fundamental difference can be recognized between olfactory “outward-journey information”, “release-site information”, etc. Signals received at different times and sites before release may contribute by varying proportions to the initial-orientation patterns observed under varying circumstances.     

Movements of Echinochrome Granules during the Early Development of Sea Urchin Eggs

ECHINOCHROME pigment granules in unfertilized eggs of the sea urchin Arbacia punctulata undergo randomly-directed saltatory movements^1,2. After fertilization, nearly all these granules migrate to the egg cortex and become embedded. Subsequent pigment granule movements may represent mass cortical changes rather than independent granule movements^2,3. At the fourth cleavage, a quartet of micromeres containing little or no pigment forms at the vegetal pole. By the two or four-cell stage, pigment granules have begun to move out of this region, leaving a “clear area” on each blastomere (Fig. 1 and refs. 4, 5). To investigate possible mechanisms for these movements and their relation to cortical events     

The analysis of stratified multiple responses

Surveys often contain qualitative variables for which respondents may select any number of the outcome categories. For instance, for the question “What type of contraception have you used?” with possible responses (oral, condom, lubricated condom, spermicide, and diaphragm), respondents would be instructed to select as many of the outcomes that apply. This situation is known as multiple responses. When the data includes stratification variables, we discuss two approaches: (1) the “GEE” approach which uses logit models directly applying the generalized estimating equations (GEE) method (Liang and Zeger, 1986); and (2) the “GMH” approach which extends the generalized Mantel–Haenszel type estimators (Greenland, 1989) to make inferences across multiple responses. These approaches can also be used for data with dependent observations across strata. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

THE EFFECTS OF WINTER LENGTH ON THE GENETICS OF APPLE AND HAWTHORN RACES OF RHAGOLETIS POMONELLA (DIPTERA: TEPHRITIDAE)

Host plant-associated fitness trade-offs are central to models of sympatric speciation proposed for certain phytophagous insects. But empirical evidence for such trade-offs is scant, which has called into question the likelihood of nonallopatric speciation. Here, we report on the second in a series of studies testing for host-related selection on pupal life-history characteristics of apple- (Malus pumila L.) and hawthorn- (Crataegus mollis L. spp.) infesting races of the Tephritid fruit fly, Rhagoletis pomonella (Walsh). In particular, we examine the effects of winter length on the genetics of these flies. We have previously found that the earlier fruiting phenology of apple trees exposes apple-fly pupae to longer periods of warm weather preceding winter than hawthorn-fly pupae. Because R. pomonella has a facultative diapause, we hypothesized that this selects for pupae with more recalcitrant pupal diapauses (or slower metabolic/development rates) in the apple-fly race. A study in which we experimentally manipulated the length of the prewintering period for hawthorn-origin pupae supported this prediction. If the period preceding winter is important for apple- and hawthorn-fly pupae, then so too should be the length (duration) of winter; the rationale for this prediction is that “fast developing” pupae that break diapause too early will deplete their energy reserves and disproportionately die during long winters. To test this possibility, we chilled apple- and hawthorn-origin pupae collected from a field site near Grant, Michigan, in a refrigerator at 4°C for time periods ranging from one week to two years. Our a priori expectation was that longer periods of cold storage would select against allozyme markers that were associated with faster rates of development in our earlier study. Since these electromorphs are typically found at higher frequencies in hawthorn flies, extending the overwintering period should favor “apple-fly alleles” in both races. The results from this “overwinter” experiment supported the diapause hypothesis. The anticipated genetic response was observed in both apple and hawthorn races, as allele frequencies became significantly more “apple-fly-like” in eclosing adults surviving longer chilling periods. This indicates that it is the combination of environmental conditions before and during winter that selects on the host races. Many tests for trade-offs fail to adequately consider the interplay between insect development, host plant phenology, and local climatic conditions. Our findings suggest that such oversight may help to explain the paucity of reported fitness trade-offs.     

Individual migration patterns of Eurasian golden plovers Pluvialis apricaria breeding in Swedish Lapland; examples of cold spell‐induced winter movements

Tracking studies normally focus on long‐distance migrants, meaning that our understanding about short‐distance migration remains limited. In this study, we present the first individual tracks of the Eurasian golden plover Pluvialis apricaria, a short‐distance migrant, which were tracked from a Scandinavian breeding population using geolocators. In addition, golden plovers are known for their cold spell‐induced winter movements, and this study provides some first individual tracking data on this type of movements. In three cases the plovers spent the winter in NW Europe and in four cases they departed during winter from NW Europe to spend the rest of the winter in Iberia or Morocco (one bird that was tracked during two subsequent migration cycles moved to Iberia in the first winter but remained in NW Europe during the second winter). The four winter departures were associated with a cold spell in NW Europe during which maximum temperatures dropped to freezing. Cold spell‐induced winter movements were notably long and fast. The birds that remained at their NW European wintering site did not experience such cold spell. However, the plovers did not always move in response to freezing temperatures, as demonstrated by the individual that was tracked for a second season, when it experienced four cold spells at its wintering site in NW France without leaving. Little information was obtained about spring migration, but one bird had a prominent counter‐clockwise loop migration pattern through E Europe. Due to their cold spell winter movements, golden plovers exhibit great flexibility in migration patterns, resulting in a notably large spread in final wintering areas.     

Chronotype,gender and general health

Background: Light–dark alternation has always been the strongest external circadian “zeitgeber” for humans. Due to its growing technological preference, our society is quickly transforming toward a progressive “eveningness” (E), with consequences on personal circadian preference (chronotype), depending on gender as well. The aim of this study was to review the available evidence of possible relationships between chronotype and gender, with relevance on disturbances that could negatively impact general health, including daily life aspects. Methods: Electronic searches of the published literature were performed in the databases MEDLINE and Web of Science, by using the Medical Subject Heading (MeSH), when available, or other specific keywords. Results: Results were grouped into four general areas, i.e. (a) “General and Cardiovascular Issues”, (b) “Psychological and Psychopathological Issues”, (c) “Sleep and Sleep-Related Issues” and (d) “School and School-Related Issues”. (a) E is associated with unhealthy and dietary habits, smoking and alcohol drinking (in younger subjects) and, in adults, with diabetes and metabolic syndrome; (b) E is associated with impulsivity and anger, depression, anxiety disorders and nightmares (especially in women), risk taking behavior, use of alcohol, coffee and stimulants, psychopathology and personality traits; (c) E has been associated, especially in young subjects, with later bedtime and wake-up time, irregular sleep–wake schedule, subjective poor sleep, school performance and motivation, health-related quality of life; (d) E was associated with lowest mood and lower overall grade point average (especially for women). Conclusions: Eveningness may impact general health, either physical or mental, sleep, school results and achievements, especially in younger age and in women. The role of family support is crucial, and parents should be deeply informed that abuse of technological devices during night hours may lead to the immature adjustment function of children’s endogenous circadian pacemakers.     

Ethnographic surreality,possession and the unconscious

In the Second Manifesto of Surrealism, issued by André Breton in 1929, surrealism was described as “a total recuperation of our psychic strength by a means of none other than vertiginous descent into ourselves, systematic illumination of the hidden places and progressive darkening of the other places, a perpetual walk in the forbidden zone”. Surrealism sought to represent the unconscious and forbidden zones of the psyche, of the body, of the noumenal world within, which offered access, for surrealists, to energies and intuitions repressed by “civilized” modes of perception. For Jean Rouch, the significance of surrealism, of automatic writing and ciné‐transe, rested in the potential escape they offered from the formal constraints of conventional film and of conventional perception and observation. In his celebration of ciné‐transe, and of the technological apparatus that makes it possible, it is possible to detect his desire for a freeing‐up of the constraints of consciousness—a desire to “write with the body”, to dream, to tap the unexplored power of the unconscious in its overturning of “reality”, of system, and of convention. As a phaneroscopic “wide‐angle lens”, surreality aimed to document the scientifically unexplainable, the immense experiential overload of ritual possession. It attempted to make visible, in the movement between observation and participation and across disjunctive points of view; the crossings‐over into the unconscious world by which possessed Songhay dancers gained access to powers of phaneroscopic perception. By adopting filmic techniques which follow the surrealist practice of creating “verbal and visual collage”, in which randomly‐generated images, emerging out of a trance‐like state (of “automatic writing” or "ciné‐transe"), are juxtaposed in indeterminate and polyphonic relations with each other in an attempt to disturb or destroy patterns of perception which are confining, rationalistic, linear, or restricted to conscious phenomena, Rouch believed he could create powerful representations of the unknowable. This paper relates the phaneroscopic practice of ethnographic surrealism to psychoanalytic models of the unconscious. In a discussion of Rouch's interpretation of the Hauka spirit cult in his film Les Maîtres Fous, the paper argues that the neo‐Freudian paradigm which allowed him to depict the Sohghay's weekend Hauka rites as a parodic reversion to “savagery” (which both reversed the hierarchy of colonizer/colonized and enabled participants to experience a therapeutic release from the traumas of colonization) has been challenged by Lacanian and post‐Lacanian “re‐readings” of Freud that call into question the extent to which the unconscious can be equated with a pre‐linguistic state characterized by disjunctive “primitive” and “instinctive” energies. The surrealist longing for a rupture of the symbolic order of Western rationalism and a return to the “imaginary order” of the unconscious is confounded in the Lacanian conception of the unconscious as a zone inhabited by the “discourse of the Other”. However, the work of Gillès Deleuze and Félix Guanari [1977] provides a means of conceptualizing the unconscious in terms that avoid simplistic binary logic (phenomenon/noumenon; signifier/signified; subject/object; conscious/unconscious; civilization/savagery). The unconscious is not the “unrepresentable” Other of consciousness; it is a schizophrenic phaneron, a signifying “machine”, a transgressive producer of “group fantasy”. Rejecting both Freud's Oedipal model (the unconscious as primal imagery or “ghostly signifieds"), and the Lacanian notion of the unconscious (as a play of “empty signifiers"). Deleuze and Guattari argue that the unconscious cannot be accounted for in terms of the individual child and its entry into language any more than it can be conceived of as the domain of the primitive. On the contrary, the unconscious is constituted as “group fantasy”, as collective public memory which need not be reduced to elemental (Oedipal) signifiers: “all delirium possesses a world‐historical, political and racial content”. The schizophrenic embodies the public nature of unconscious meaning, since schizophrenia is primarily a communication disorder in which an individual never sees himself in terms of a linguistically‐generated “selfhood”, and fails to adopt the “false” identity which is offered to him in the language of the Other. Schizophrenia is characterized by a refusal to treat some meanings as superior to others, to remain within the bounds of a stable identity, or to distinguish between material (noumenal) things and actions and their (phenomenal) meanings. The schizophrenic unconscious treats all experience as signs, registering language in the same way as the body registers physical stimuli. Thus “meanings in the unconscious are simply meanings as workings of the body” [Harland 1987:174–175]. The schizophrenic as a model for the unconscious holds several implications for those interested in representing the experiential power of public rituals, for the public meanings in circulation during such rituals are material and noumenal, and are registered on the bodies of the dancers as they transgress boundaries and pass beyond consciousness. Rouch's surreality attempted to inscribe this unconscious production of public meaning as it was manifested in the movements of the ritual and in the movements of the camera‐body.     

Translocation of the Eastern Bristlebird 1: radio‐tracking of post‐release movements

Summary Translocating birds to a new area of habitat to restore or supplement depleted populations may pose a significant threat to the translocated individuals. While for many species, translocated individuals appear to move larger distances than resident animals, species with poor dispersal capacity may be restricted in movements and translocation methods may need to accommodate differences in movements to ensure success. In this study, designed to provide insights to inform our broader programme of translocations in New South Wales, Australia, we investigated post‐release movements in the endangered, semi‐flightless Eastern Bristlebird (Dasyornis brachypterus). We predicted that movements would be minimal, with few differences between males and females, similar to published information for a resident un‐manipulated population. Following the release of 45 birds at a host location at Jervis Bay, NSW, over a 3‐year programme, we followed individuals for up to 2 weeks using radio‐tracking. The translocated birds had larger maximum movements and moved through much larger home ranges than non‐translocated individuals from the resident population. Translocated birds moved 300 m further after release when conspecifics were present. Males moved further than females and tended to have larger home ranges, although average daily displacement did not differ. We concluded that the semi‐flightlessness of the species does not result in minimal movements. Release at a small number of locations in the new habitat was considered appropriate for the species, as animals seem to move enough to find new unoccupied areas in a relatively short period. This work provided us with increasing confidence to continue with further translocations.     

Home range of greater and lesser rhea in Argentina : relevance to conservation

In this work we report results of radiotracking studies on the movements and home range sizes of two near-threatened species, the greater rhea (Rhea americana) and the lesser rhea (Pterocnemia pennata pennata) in relation to different land use regimes. We radiomonitored greater and lesser rheas for 3 years in their respective habitats: the Pampas and the Patagonia regions. We chose two study areas in each habitat with similar agricultural activities and different hunting control. We did not find significant differences in movements and home range size between study areas of each species. This suggests that disturbance caused by human presence in the areas did not affect rhea spacing behaviors. Moreover, lesser rheas showed larger home range and movements than greater rheas, showing that the home range size is not an immutable property of body mass, and that abundance and distribution of food appears to be the main factor that influences the movements and home range size of these birds.     

Lateralized behavior in two captive bottlenose dolphins (Tursiops truncatus)

The study of behavioral laterality in humans and nonhumans can contribute to our understanding of brain evolution and functional similarities across species. Few studies have focused on cetaceans. This report exams lateralized behaviors in two captive bottlenose dolphins (Tursiops truncatus). Observations were made by videotaping through a 90 × 150 cm underwater one-way Plexiglass mirror. Directional bias in swimming, “barrel-roll” maneuvers, and circular head movements was assessed for each subject. There was a strong clockwise bias in swimming direction and direction of “barrel-rolls,” but not circular head movements. The clockwise bias in swimming direction and “barrel-roll” maneuvers may be consistent with a rightward turning bias. Zoo Biol 16:173–177, 1997. © 1997 Wiley-Liss, Inc.     

DISPERSAL BY YEARLING MALE WHITE-TAILED DEER AND IMPLICATIONS FOR MANAGEMENT

Abstract: The scale at which populations use the landscape influences ecological processes and management decisions. Dispersal and home-range size define the scale of landscape use for many large-mammal species. We measured dispersal and home-range size of yearling male white-tailed deer (Odocoileus virginianus) in southern Texas, and compared our results to values from the literature to understand the implications of dispersal in management of deer populations. We used radiotelemetry to monitor 22 yearling deer on 1 study site from October 1998 to October 1999, and 27 yearling deer on a second study site from October 1999 to October 2000. On the 2 study sites, 68% and 44% of yearling deer established new areas of use 4.4 ± 1.0 km and 8.2 ± 4.3 km, respectively, from the center of their autumn home range. Yearling males with spike antlers (2 points) were less likely to disperse than yearlings with fork antlers (>2 points) on 1 study site. Computer simulation showed that the scale at which deer use the landscape is large compared to property sizes in southern Texas and probably in other areas of the white-tailed deer's range. Differences in scale between land ownership patterns and landscape use by deer may result in a failure to meet management objectives and conflict among managers. High harvest rates for male deer occur in part because deer movements are large relative to property size, creating a “tragedy of the commons.” Cooperative management groups are beneficial if all landowners in an area agree on management objectives. Otherwise, deer-proof fences often are erected to reduce conflicts among property owners.