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To better understand the mechanisms that lead to marine mortality of homing adult sockeye salmon (Oncorhynchus nerka), gill and blood biopsies were used in combination with biotelemetry to demonstrate how survival to freshwater entry is related to gene expression and physiological indices of stress. Microarray analysis of gene expression indicated multiple biological processes, including immune and stress responses, protein biosynthesis, and metabolism. Quantitative reversetranscriptase polymerase chain reaction (qRT-PCR) analysis indicated fish with upregulation of genes related to stress and infection had higher marine survival compared with fish without this genomic signature. We proposed that higher marine survival of potentially stressed and immune compromised fish can be explained by stressed and infected fish being highly motivated to enter fresh water, leading to enhanced marine survival. However, once in a river, stressed and immune compromised fish could suffer higher mortality because of premature river entry. Overall, this study supports the idea that infection and stress are important biological processes influencing behaviour and fate of sockeye salmon during homing migrations. Pour mieux comprendre les mecanismes dont decoule la mortalite en mer de saumons rouges (Oncorhynchus nerka) adultes en migration de retour, des biopsies de branchies et de sang ont ete utilisees de concert avec la biotelemetrie pour etablir comment la survie jusqu'a l'entree en eau douce est reliee a l'expression genique et a des indices physiologiques du stress. L'analyse de l'expression genique a l'aide de biopuces fait ressortir plusieurs processus biologiques, dont des reactions immunitaires et de stress, la biosynthese de proteines et le metabolisme. L'analyse qRT-PCR indique que les poissons presentant une regulation positive des genes associes au stress et a l'infection ont un taux de survie en mer plus eleve que les poissons ne presentant pas cette signature genomique. Nous proposons que la plus grande survie en mer de poissons potentiellement stresses et immunocompromis peut s'expliquer par le fait que les poissons stresses et infectes seraient plus motives a entrer en eau douce, ce qui se traduirait par un taux de survie en mer plus grand. Une fois en riviere, cependant, les poissons stresses et immunocompromis pourraient avoir une plus forte mortalite en raison de leur entree prematuree en riviere. Globalement, les resultats de l'etude appuient la notion voulant que l'infection et le stress soient d processus biologiques qui influencent le comportement et le destin des saumons rouges durant leurs migrations de retour. [Traduit par la Redaction], Introduction Anadromous salmonids (from Salmo, Oncorhynchus, and Salvelinus genera) migrate from ocean feeding grounds to fresh water to reproduce, during which migrants undergo extensive physiological shifts associated with reproductive maturation [...]

The influence of model complexity on integrated tagging and catch-at-age analysis (ITCAAN) parameter estimation is poorly understood for populations exhibiting natal homing. We investigated ITCAAN performance under varying levels of movement, degree of similarity in population productivities, data quality, spatial complexity in parameterization, and whether natural mortality and (or) reporting rates were fixed at actual values, estimated, or misspecified. Dynamics of four populations with natal homing that intermixed during periods of harvest were simulated based on Lake Erie walleye (Sander vitreus). Our results suggest, when high-quality tagging data are available, ITCAAN models are able to simultaneously estimate movement rates, natural mortality, and tag reporting rates, though accuracy and precision of model estimates will decrease with greater model complexity and fewer tags released. Additionally, ITCAAN models may have difficulty estimating individual population abundances under certain movement rates when population productivities are vastly different. ITCAAN models that estimate natural mortality and reporting rates may perform best with similar sized populations and when data are available to assist the estimation of reporting rates. L'influence de la complexity du modele sur l'estimation des parametres de modeles d'analyse integree de l'etiquetage et de la capture a l'age (ITCAAN) est mal comprise pour les populations caracterisees par une migration vers le lieu de naissance. Nous avons examine la performance de l'ITCAAN pour differents degres de deplacement et de similitude des productivites des populations, de qualite des donnees et de complexity spatiale du parametrage, et selon que les taux de mortalite naturelle ou de signalement sont fixes a des valeurs reelles, estimees ou erronees. La dynamique de quatre populations dont les migrations de retour au lieu de naissance se melangent durant des periodes de peche a ete simulee sur la base du dore jaune (Sander vitreus) du lac Erie. Nos resultats portent a croire que, quand des donnees d'etiquetage de haute qualite sont disponibles, les modeles ITCAAN peuvent estimer simultanement les frequences de deplacement et les taux de mortalite naturelle et de signalement d'etiquettes, bien que l'exactitude et la precision des estimations de ces modeles diminuent quand la complexite du modele augmente et le nombre d'etiquettes relachees diminue. Les modeles ITCAAN pourraient en outre peiner a estimer l'abondance de populations precises pour certaines frequences de deplacement quand les productivites des populations sont tres differentes. Les modeles ITCAAN qui estiment les taux de mortalite naturelle et de signalement pourraient donner les meilleurs resultats pour des populations de tailles semblables et quand des donnees sont disponibles pour appuyer l'estimation des taux de signalement. [Traduit par la Redaction], Introduction Fishery scientists and managers commonly assume fish harvested in a single management unit originate from an isolated spawning population (Beverton and Holt 1957). The validity of this assumption has [...]

Little is known about Atlantic salmon behaviour during the last phase of the marine homing migration and subsequent river entry. In this study, 56 adult Atlantic salmon in the Alta Fjord in northern Norway were equipped with acoustic transmitters. Salmon generally followed the coastline, but their horizontal distribution was also affected by wind-induced spreading of river water across the fjord. Mean swimming depth was shallow (2.5-0.5 m), but with dives down to 30 m depth. Timing of river entry was not affected by river flow, diel periodicity, or tidal cycles. Movements during the last part of the marine migration and river entry were unidirectional and relatively fast (mean 9.7 km*[day.sup.-1] ). However, migratory speed slowed as salmon approached the estuary, with a significantly lower speed in the innermost part of the estuary than in the open fjord. Migration behaviour seemed not to be affected by handling and tagging, as there were no behavioural differences between newly tagged fish and those captured and tagged 1 year before their homing migration. Les connaissances sur le comportement du saumon atlantique durant la derniere phase de sa migration de retour en mer et son entree subsequente en riviere sont tres limitees. Dans la presente etude, 56 saumons atlantiques adultes dans le fjord Alta du Nord de la Norvege ont ete equipes d'emetteurs acoustiques. En general, les saumons suivaient la cote, mais leur repartition horizontale etait egalement influencee par la dispersion eolienne des eaux fluviales dans le fjord. Si la profondeur de nage moyenne etait faible (2,5 a 0,5 m), les poissons pouvaient atteindre 30 m de profondeur en plongee. Le debit de la riviere, la periodicite quotidienne et les cycles des marees n'avaient pas d'incidence sur le moment de l'entree en riviere. Les deplacements durant l'ultime portion de la migration en mer et l'entree en riviere etaient unidirectionnels et relativement rapides (9,7 km*[jour.sup.-1] en moyenne). La vitesse migratoire diminuait toutefois a mesure que les saumons s'approchaient de l'estuaire, les vitesses etant significativement plus faibles dans la partie la plus amont de l'estuaire que dans le fjord ouvert. Le comportement de migration semblait ne pas etre influence par la manipulation et le marquage, puisqu'aucune difference sur le plan du comportement n'a ete observee entre les poissons nouvellement marques et ceux qui avaient ete captures et marques 1 an avant leur migration de retour. [Traduit par la Redaction], Introduction Atlantic salmon (Salmo salar) is a species of great biological, cultural, and economic importance. Abundance, marine survival, and in some cases growth have declined in large parts of the [...]

All offshore oil and gas platforms have finite economic life spans. One of the decommissioning options for these platforms is complete removal, requiring the use of explosives to dislodge the [...]

Several marine animals, including salmon and sea turtles, disperse across vast expanses of ocean before returning as adults to their natal areas to reproduce. How animals accomplish such feats of natal homing has remained an enduring mystery. Salmon are known to use chemical cues to identify their home rivers at the end of spawning migrations. Such cues, however, do not extend far enough into the ocean to guide migratory movements that begin in open-sea locations hundreds or thousands of kilometers away. Similarly, how sea turtles reach their nesting areas from distant sites is unknown. However, both salmon and sea turtles detect the magnetic field of the Earth and use it as a directional cue. In addition, sea turtles derive positional information from two magnetic elements (inclination angle and intensity) that vary predictably across the globe and endow different geographic areas with unique magnetic signatures. Here we propose that salmon and sea turtles imprint on the magnetic field of their natal areas and later use this information to direct natal homing. This novel hypothesis provides the first plausible explanation for how marine animals can navigate to natal areas from distant oceanic locations. The hypothesis appears to be compatible with present and recent rates of field change (secular variation); one implication, however, is that unusually rapid changes in the Earth's field, as occasionally occur during geomagnetic polarity reversals, may affect ecological processes by disrupting natal homing, resulting in widespread colonization events and changes in population structure. migration | navigation | magnetic | magnetoreception | fish

Research concerning the importance of philopatry to stopover sites in the Bet Shean Valley in Israel for Reed Warblers preparing to cross the Sahara Desert is presented. Adult birds arrive earlier than youngsters.

Research was conducted to examine roost selection in the pipistrelle bat, Pipistrellus pipistrellus. Nine internal and 26 external characteristics of 21 known roost buildings were compared to 17 random buildings located in northeast Scotland. Common selection features were the presence of a nearby tree and the existence of linear vegetation leading away from the bats. The best indicator for bats roosting in buildings is percentage cover within 50 m of the building.

The influence of non-polarized light on the direct homing of grass ants, Tetramorium caespitum, was investigated under different conditions to determine if these ants use light as homing cues. Results reveal that ants can home under blue and overcast skies and non-polarized light. The homing mechanism appear to be a form of dead reckoning where the ants integrate directional and distance changes made during the outward trip into the homeward path.

The honey bee's ability to take short cuts between two feeding sites was investigated to determine the existence of cognitive maps in these insects. Findings showed that bees never took shortcuts but used homeward directions in reaching the sites. Bees that have been trained in only one feeding site were not able to travel directly home. These results suggested that inference of a cognitive map in bees would br premature.

A bird-borne data logger, which stores flight directions at regular intervals, was used to reveal the foraging patterns of Thick-billed Murres (Uria lomvia) breeding at Latrabjarg in northwestern Iceland. Tracked birds traveled 10 to 168 km one-way to foraging sites in a narrow sector to the northwest of the breeding colony. The pattern of foraging activity was rather constant. Outbound birds stopped briefly several times, possibly testing prey availability. The longest stops occurred at sites close by the turning point of the outbound journey. During the inbound flight, stops were less frequent and shorter than on the outbound flight, suggesting that the sequence of stops was not the expression of a disturbance caused by the instruments.

Recent studies of mitochondrial DNA (mtDNA) variation among marine turtle populations are consistent with the hypothesis that females return to beaches in their natal region to nest as adults. In contrast, less is known about breeding migrations of male marine turtles and whether they too are philopatric to natal regions. Studies of geographic structuring of restriction fragment and microsatellite polymorphisms at anonymous nuclear loci in green turtle (Chelonia mydas) populations indicate that nuclear gene flow is higher than estimates from mtDNA analyses. Regional populations from the northern and southern Great Barrier Reef were distinct for mtDNA but indistinguishable at nuclear loci, whereas the Gulf of Carpentaria (northern Australia) population was distinct for both types of marker. To assess whether this result was due to reduced philopatry of males across the Great Barrier Reef, we determined the mtDNA haplotypes of breeding males at courtship areas for comparison with breeding females from the same three locations. We used a PCR-restriction fragment length polymorphism approach to determine control region haplotypes and designed mismatch primers for the identification of specific haplotypes. The mtDNA haplotype frequencies were not significantly different between males and females at any of the three areas and estimates of [F.sub.st] among the regions were similar for males and females ([F.sub.st] = 0.78 and 0.73, respectively). We conclude that breeding males, like females, are philopatric to courtship areas within their natal region. Nuclear gene flow between populations is most likely occurring through matings during migrations of both males and females through nonnatal courtship areas.

The role of olfaction on the homing ability of precocial or semi-precocial chicks of underground-nesting seabirds were analyzed in Hydrobates pelagicus or the British storm-petrel. Homing experiments with the British storm-petrel chicks indicated the absence of parent-offspring recognition after the end of brooding. However, British storm-petrel chicks exhibited olfactory homing abilities and are capable of nest recognition which were crucial for survival.

Translocation is increasingly being advocated as a nonlethal management alternative for species, particularly mammals. The efficiency of translocation was evaluated based on the trapability, site fidelity, post release survival and homing ability of California ground squirrels. The survival rate until 18 days after translocation was 71-79%, with mortality highest soon after release. 85% established new home ranges, but homing success was lower with translocation distance. Translocation is probably not suitable for squirrel control over large areas, but has potential for use in smaller areas.

During a field experiment on density-dependent processes in meadow voles (Microtus pennsylvanicus), we removed 848 voles from field enclosures and released them 1,200 m away. Eleven animals (1.3%) returned to the enclosure from which they had been removed, which entailed traversing inhospitable habitat (forest, wetland), obstacles (permanent stream, roads), and climbing a 0.9-m hardware-cloth fence surrounding the enclosures. For six of the 11 voles, returning home was accomplished in > 2 but < 4 weeks; the others returned in [less than or equal to]2 weeks. Voles returning home, which averaged ca. 30 g, lost on average 5.3% of their body mass during homing, unlike their resident counterparts, which gained mass. The voles that homed could not have used familiar objects as cues for navigation, but whether they used distant points of reference or wandered randomly is unknown. Our findings suggest that meadow voles are capable of travelling > 1 km toward home, and thus, it is likely that they could travel similar distances while dispersing. Key words: Microtus pennsylvanicus, meadow vole, dispersal, long-distance homing, movement distances

Homing pigeons were raised and trained in two lofts that differed with respect to their color features and location in space. During training, pigeons displayed accurate site preference for a particular loft. When tested for loft preference with the feature cues switched between the 2 lofts, the pigeons returned to the loft that occupied the correct location. In a 2nd experiment, pigeons were trained to find food hidden in 1 of 4 color bowls (feature cues) located next to a landmark beacon (proximal spatial cue) in a constant location in a room (distal spatial cues). On test trials, pigeons chose the bowl at the correct location in the room if either the color bowl or the beacon was moved by itself but chose the correct color bowl next to the beacon if they were moved together. Together, the data suggest that the importance of location and feature information for goal recognition may be context specific.

A study has been conducted to examine the effect of relocation on the survival of the grizzly bear, Ursus arctos, transported in the Yellowstone National Park. Survival was determined according to the ability of the bears to return to the capture site. Transported bears had lower survival rates than those not transported. Bears that were transported at distances greater than 75 km. decreased their return rates. These results suggest that the homing ability of bears is influenced by distance. Results also suggest that return rates and survival rates are determined by the bears' age-sex group.

A study was conducted to examine animal locations and movements of black-tailed deer using Schoener's Ratio at four sites on Vancouver Island, British Columbia, from 1982-1984. Location data were obtained by measuring bearings at three separate stations with 100-m. intervals. Datasets which lack independence were attributed to migrations and animal movements within the home range. These observations skewed data distributions and eliminated normality in the independence test. Thus, it is suggested to examine animal locations symmetrically based on time rather than on time intervals.

In Experiment 1, hamsters started from their permanent home at the periphery of a circular arena and headed to a food source at the center. They then returned, fully laden with food, along a direct path to their home. On control trials, in which no manipulation takes place, visual cues outside the arena and dead reckoning (i.e., updated internal references generated during the outward journey to the food source) controlled the return journey. On experimental trials, the arena, with the hamster in its nest, was rotated by 90 degrees, putting dead reckoning at variance with the distal visual environment. The animals were rewarded for going with dead reckoning. At first, they favored the distal cues, but later most of the subjects switched to using dead reckoning. Thus, hamsters are flexible enough to recalibrate the relative weight that they normally attribute to different sets of spatial cues. In Experiment 2, the reliance on dead reckoning was greatly enhanced when a cue card at the nest entrance was rotated along with the arena, pitting one proximal cue plus dead reckoning against distal cues. Hence, dead reckoning and external cues seem to reinforce each other through their mutual correlation.

Aerial surveys to locate radio-marked Canada geese (Branta canadensis interior) of the Mississippi Valley Population (MVP) indicated fall and spring migration 1984-86 was concentrated in a corridor in central Illinois and southeastern Wisconsin. A major spring staging area was identified in the Kaskaskia River Valley of central Illinois. Chronology of departure from wintering areas varied annually, but timing of departure from Wisconsin staging areas and arrival on nesting areas in Ontario was similar among years. Chronology of fall migration varied annually, and timing of movements of birds from Wisconsin to southern Illinois caused underestimates in midwinter population inventories (conducted mid-Dec) in 3 of 4 years. Homing rates of segments of the MVP associated with fall staging in Winconsin versus southern Illinois did not differ (P > 0.20) from rates that could be expected based on numbers of geese using Wisconsin versus Illinois in fall. We found no evidence to support the existence of manageable subpopulations of the MVP.

An isolated, unpaired, male red-cockaded woodpecker, in danger of losing its habitat because of a planned timber harvest, was moved 16.7 km to a reserve in Vernon Parish, LA. Subsequent observations show that the bird returned to the captive site, despite being relocated twice more. After the third translocation, he was again captured at the captive site. The study suggests that the distance between the capture and release sites should be more than 20 km if the birds are not to return to the original site.

The Atlantic salmon is renowned for long migrations in the ocean and, more important, precise homing to its original river. A study shows that the Atlantic salmon homes by learning which river it left during migration. However, homing is not perfect and, sometimes, it stray into foreign rivers. When salmons beget offsprings, the progenies that survive adopt the new river as their home.

Several studies and tools are employed to explain the spatial ecology and to determine the diurnal annual and seasonal home-range size for male and female lynx in northern Maine. The spatial ecology and densities of the southern and northern lynx populations are shown to be quite similar in the presence of large number of hares.

Habitat loss and fragmentation affect forest birds through direct loss of breeding habitats, detrimental edge effects such as increased nest predation and brood parasitism, and possibly by limiting movements among remaining forest patches. Despite indirect evidence suggesting that landscape-scale bird movements are constrained by open areas, skepticism remains because birds routinely cross inhospitable terrain during migration. Here, we report evidence from 201 independent homing trials showing that landscape composition and configuration influence the movements (1-4 km) of two neotropical migrant (Black-throated Blue Warbler, Dendroica caerulescens and the Ovenbird, Seiurus aurocapillus) and one resident (Black-capped Chickadee, Poecile atricapillus) forest bird species in Quebec, Canada. Trials consisted of translocating territorial, mated males and measuring the time they needed to return to their territories (homing time), as well as the probability with which they returned to their territories within 30 h (homing success). Birds took more time and were less likely to return to their territories as forest cover decreased in the landscape. Once the simple linear variation due to forest cover was removed from landscape configuration variables, their influence on homing time and success was nonexistent or subtle, suggesting that landscape composition has greater predictive value than landscape configuration to infer constraints on forest bird movements. Indeed, and contrary to our expectation, mean nearest-neighbor distance between forest patches had no impact on homing time or success, but its coefficient of variation was positively correlated with homing time and negatively correlated with homing success. On the other hand, homing time and success were not influenced by the number of forest patches or the amount of edge per unit of forest cover. These results were consistent for all three bird species that we studied. Our data support the hypothesis that movements are constrained when forest birds travel in deforested and fragmented landscapes outside migratory periods. Such an impediment is likely to disrupt habitat selection processes, reduce the colonization of isolated forest patches, and ultimately, alter population structure and dynamics. Key words: agricultural landscape; Black-capped Chickadee; Black-throated Blue Warbler; connectivity; corridor; dispersal; forest cover; fragmentation; habitat loss; movement; Ovenbird.

Two series of homing experiments were carried out with wood mice (Apodemus sylvaticus). In the first experiment wood mice were released at a place near their home-range boudaries where they had previously gone spontaneously before being trapped. In the second experiment they were transported and released 1 km away from their home. Although the same experimental procedure was used in both experiments, the wood mice oriented homeward consistently in the first but randomly in the second experiment. This indicates that the wood mice were incapable of location-based navigation when transported outside their familiar area. In the long-distance-release experiments, some variations in their movement patterns related to the place of release suggest that the mice searched for familiar cues even in a completely unknown place.

Four pigeons previously trained to home to the roof of the University of British Columbia psychology building and 4 nonhoming pigeons were trained to discriminate between two sets of color slides projected onto a pecking panel of a Skinner box. One slide set consisted of photographs taken in the vicinity of the psychology building; the other set consisted of similar views taken at locations not previously visited by the homing subjects. All subjects were rewarded for pecking during slides from the first but not the second set. Every few sessions, new 'Home' and 'Away' slides were introduced during transfer tests. In a final transfer test, a completely new tray of Home and Away slides was introduced. The homing pigeons were slightly (but not statistically significantly) better at discriminating Home from Away slides. The implications of these results for understanding pigeons' homing behavior, concept attainment, and spatial memory are discussed.

Pinyon Jays (Gymnorhinus cyanocephalus) live in permanent flocks of 50-500 individuals on apparently undefended home ranges. We present date collected from 1973 to 1982 on the movement of individuals into and out of a color-banded flock. We banded 681 wanderers from other flocks, 46 of whom immigrated and bred in the study flock. Three hundred and eighty-three juveniles and yearlings born in the study flock disappeared from the natal flock; 22 of these bred in a neighboring flock. One was collected in 1973 as a yearling 600 km from its place of birth. Most dispersal occurred in the fall, but yearling females also dispersed during the breeding seasons. Fall dispersal was primarily by juveniles and included males and females in equal abundance. Females transferred between neighboring flocks more often than males. Many males returned to their natal flocks after months of wandering. As a result, 89% of male yearlings, but only 48% of female yearlings, in the study flock were born there. Annual variability in dispersal by yearlings was correlated with sex ratio in their natal and neighboring flocks; females joined flocks with strongly male-biased sex ratios and females left flocks with female-biased sex ratios. Low status of juveniles and yearlings, especially females, may explain why some dispersal occurred each year regardless of the sex ratio of the flock. Homing ability and the number of relatives in a flock were only weakly related to the percentage of yearlings and juveniles emigrating. Five consequences of dispersal were: (1) flock members may become familiar with resources outside their home range; (2) the sex ratio of yearlings approaches 1:1, despite extreme and variable sex ratio biases among yearlings born in the flock; (3) in some years the yearling cohort is predominantly composed of immigrants and in other years natives predominate; (4) immigrants have fewer relatives in the flock than natives have; and (5) the effective population size ranges from 222 to 370 and includes breeders of a flock and breeders in neighboring flocks.

Recent research on the homing mechanisms of pigeons may soon shed light on the issue and initiate further studies on pigeon behavior. More data are pouring in which indicate the presence of a magnetic based receptor in some species. More experiments are also being conducted on the mechanism of light-dependent magnetic sensors. The rational behind the 'village effect' or the tendency to fly towards villages is still under debate.

Philopatry in migratory species can apply to any location used during the annual cycle. The degree of philopatry influences the genetic structure of populations, but only at the stage of the annual cycle when pair formation and gene exchange occur. Because pair formation in birds typically occurs during the breeding season, most studies have focused on breeding-site philopatry. Waterfowl (Anseriformes) are an important exception to this pattern because pair formation often occurs during the winter months. Yet, surprisingly few studies have examined winter philopatry in waterfowl. To serve as an impetus for future research, we summarize published information on winter philopatry in waterfowl and examine these patterns in light of current hypotheses proposed to explain philopatric behavior. Our analyses indicate that geese, swans, and sea ducks show high levels of winter philopatry, with homing rates varying between 49 and 98% to small study areas. In contrast, return rates (0 to 20%) and homing rates (35 to 85%) to large study areas probably are comparatively lower for dabbling ducks and pochards. Unfortunately, detailed comparisons among groups are hindered by variation in the scale at which philopatric behavior is evaluated (ranging from

The home range area and the factors affecting it were studied in Red morwong, Cheilodactylus fuscus, samples in Australia. It was believed that diurnal, seasonal and behavioral changes affected home range and habitat utilization. Using ultrasonic transmitters, it was observed that the home range of the red morwong markedly changed between night and day with night movement characterized by non-directional movement over a diverse area. The fish population was maintained in one area by the homing ability. Persistent aggregations were observed exclusively on bouldered substrata.