SUMMARY 10 carrier pigeons subjected to olfactory nerve section showed abnormal behaviour when released 54 km from the loft and very poor homing as compared with sham operated controls.

SUMMARY Two groups of one year old pigeons, trained from two opposite directions, were released under overcast and under sun from two places off the training lines, 31 and 58 km from the loft. Pigeons oriented correctly in all the releases; under sun, the two groups deflected from each other in a manner predictable according to the training, but no deflection was observed under overcast.

SUMMARY New experiments have been made on homing pigeons deprived of olfactory perception by occlusion of both nostrils with cotton tampons, or by resection of the olfactory nerve on one side and occlusion of the nostril on the other. They confirm the strong disturbance of orientation of the birds at the moment of release, which had already been observed in subjects with both olfactory nerves resected. Observations conducted on subjects with resected nerves have not shown other disturbances in general behaviour. The possibility is considered that, at the home site, pigeons associate odorous stimuli carried by winds from the surroundings with the direction from which they come. Recognizing a known odour at the release point, they should thereby be able to orient themselves toward home by flying in a direction opposite to the one with which the odour had been associated.

SUMMARY With 106 homing pigeons belonging to two different lofts (Florence and San Piero a Grado, near Pisa) 209 vanishing points were noted from release sites in the open sea and on land at a distance varying between 100 and 255 km from the loft. In five releases in the Tyrrhenian Sea the animals took average directions varying from 111° to 169° showing a tendency in all five releases to fly towards SE: the deviation from the average vector of the home direction resulted as 120°, 72°, 50°, 87°, and 150°. In two releases from the Adriatic the vanishing points were distributed at random, or were accumulated in a direction opposed to that expected (average deviation from the home direction = 174°). In six releases on land there was only one case of random distribution of the vanishing points, while in the other five a correct orientation towards home was noted with a deviation of the average vector from the home direction of 4°, 26°, 27°, 43′° and 48°. In the releases from land 11 out of 87 adults (12.6%) w...

SUMMARY In the course of 10 experiments, initial orientation and homing performance of 12 groups of pigeons to which odorous substances were applied near to and/or on the nostrils have been recorded. The substances used were: α-pinene, olive oil and a mixture of substances extracted with ether from 12 different plants. Besides an increase in the vanishing time, these odorous substances induce deviations of the mean vector and/or increase, to various degrees, the scattering of the vanishing points. The homing performances of the experimental birds are altogether worse than those of the control birds. These results agree with the hypothesis of olfactory navigation in homing pigeons.

Evidence suggests that paw preferences are related to emotional functioning in the domestic dog. Whether motor bias in this species is related to the display of behaviour problems, which often have their basis in emotional reactivity, is still unknown. This study therefore explored the relationship between lateralised motor behaviour in the form of paw preferences and the occurrence of canine behaviour problems. Fifty-two dogs presenting with one or more behaviour problems, and 61 control animals, had their paw preferences assessed using the commonly employed Kong™ ball test. The dogs’ behavioural profile was determined using the C-BARQ, a psychometric tool designed to provide standardized evaluations of canine behaviour. Analysis revealed a roughly equal split in the proportion of dogs classified as ambilateral and lateralised, although dogs were more like to be ambilateral than left- or right-pawed. Dogs differed significantly in their behavioural profile, with animals in the behaviour problem group displaying more severe patterns of stranger- and dog-directed aggression and fear, non-social fear and touch sensitivity than those in the control group. There was no significant difference in the distribution, direction or strength of the dogs’ paw use between the two groups of animals. The dogs’ paw preference classification was significantly associated with one of the C-BARQ subscale scores, namely stranger-directed aggression, with left-pawed dogs having lower scores on this subscale than right-pawed or ambilateral animals. The direction of the dogs’ paw use in the behaviour problem group was significantly correlated with C-BARQ scores for the subscales of stranger-directed aggression, stranger-directed fear and attention-seeking behaviour, with higher subscale scores associated with increasing right-pawedness. There was no significant correlation between the direction of the dogs’ paw use and any of the other C-BARQ subscale scores. The strength of the dogs’ paw preferences was not significantly correlated with any of the C-BARQ subscale scores for either the control or behaviour problem group of animals. Canine sex was not significantly related to either the dogs’ paw preferences or the presentation of behaviour problems. Overall, this study provides little evidence in support of a relationship between paw preference and the occurrence of behaviour problems in the domestic dog. Further, longitudinal, work is recommended in an effort to unravel the ontogeny of lateralisation and its association with emotional reactivity in this species.

Evidence from clinical and animal research highlights the role of the hippocampus in long-term memory (LTM). Decades of experimental work have produced numerous theoretical accounts of the hippocampus in LTM, and each suggests that hippocampal disruption produces amnesia for specific categories of memory. These accounts also imply that hippocampal disruption before or soon after a learning episode should have equivalent amnestic effects. Recent evidence from lesion and inactivation experiments in rodents illustrates that hippocampal disruption after a learning episode causes memory impairment in a wider range of memory tasks than if the same disruption occurs before learning. Although this finding supports that multiple circuits can acquire and retrieve similar information, it also suggests they do not do so independently. In addition, damage after learning produces amnesia for simple elements of a task as well as complex, conjunctive features. Here we develop an explanation for why anterograde and retrograde hippocampal effects differ. This explanation, the heterarchic reinstatement view, also generates novel predictions.

The diving behaviour of four leatherback turtles (Dermochelys coriacea) was recorded for periods of 0.5–8.1 months during their postnesting movements in the Indian and Atlantic Oceans, when they covered 1569–18,994 km. Dive data were obtained using satellite-linked transmitters which also provided information on the dive depths and profiles of the turtles. Turtles mainly dove to depths <200 m, with maximum dive durations under 30–40 min and exhibited diel variations in their diving activity for most part of the routes, with dives being usually longer at night. Diurnal dives were in general quite short, but cases of very deep (>900 m) and prolonged (>70 min) dives were however recorded only during daytime. The three turtles that were tracked for the longest time showed a marked change in behaviour during the tracking, decreasing their dive durations and ceasing to dive deeply. Moreover, diel variations disappeared, with nocturnal dives becoming short and numerous. This change in turtle diving activity appeared to be related to water temperature, suggesting an influence of seasonal prey availability on their diving behaviour. The turtle diving activity was independent on the shape of their routes, with no changes between linear movements in the core of main currents or looping segments in presence of oceanic eddies.

The animals from the environments focused on here share the same navigational mechanisms with terrestrial animals. However, some of them seem to rely on additional ways of detecting and/or processing navigational cues, some of which are perhaps still unknown. A classification of the mechanisms of navigation is given. This is based on the source of information that animals use to head for their targets. A selected series of phenomena of current interest is presented, starting with olfactory beaconing in oceanic birds, which allows the detection of patchily distributed food and productive areas from long distances. Animals of sandy beaches rely on an array of mechanisms of orientation, which have an adaptive value for their ecotonal system. As some species are capable of using both the moon and sun compass in orientation, attention and experiments are focused on the significance of these celestial cues in the navigational process. Two clocks of different periods, one of which would appear to regulate both the activity rhythm and the sun compass, are presumed to underlie the two compass mechanisms. The feats of global navigators in and over the oceans are especially puzzling considering their ability of homing to the natal and nesting sites after long lasting, extended wandering in the open ocean, and of pinpointing tiny, isolated oceanic islands. The existent literature allows comparison of the navigational capabilities of oceanic birds with those of sea turtles. Their performances in natural conditions seem to be similar, but sea turtles exhibit a reduced capacity of compensation for experimental relocation. Capacity of positioning based on geomagnetic parameters has been indicated for sea turtles through laboratory experiments, but this is not confirmed by the routes of magnetically disturbed turtles tracked while migrating or attempting to compensate for relocation. Also albatrosses with fitted magnets are not disturbed in their homing.

Sea turtle movements often occur in open-sea unsheltered areas, and are therefore likely to be influenced by major oceanographic processes. Only recently has work started to examine the possible relationships of these movements with dynamic oceanic features, and consequently a clear picture of such interaction is only available in a few cases.Newborn sea turtles are thought to rely on oceanic currents to reach their pelagic nursery habitats. The actual extent and timing of these developmental migrations are known for only a few populations, but these movements probably last several years and range over thousands of km. Large juveniles that have been tracked during their pelagic stage were found to make long-distance movements, sometimes swimming against the prevailing currents. Older juveniles of most species leave the pelagic habitat to recruit to neritic developmental habitats. This is a very poorly documented phase of the sea turtle life-cycle, and the few available indications show that turtles may have to swim actively for enormous distances to counterbalance their previous drift with the current.The course and extent of adult postnesting migrations vary greatly among different turtle species, but two main patterns are evident. Some species, like green, hawksbill and loggerhead turtles, shuttle between the nesting beach and a specific feeding area used for the entire inter-reproductive period. In these cases, individuals swim, rather than drift, to complete their journeys, with possible advection due to currents sometimes helping them to quickly reach their target, but sometimes providing navigational challenges.Other species such as the olive ridley and the leatherback turtle, leave the coastal nesting areas to reach the pelagic environment where they forage, and perform wandering movements. Major oceanographic processes (such as main currents and eddies) have been recently shown to have a remarkable influence on leatherback movements, making it questionable whether these journeys are to be considered migrations or, rather, prolonged stays in vast feeding areas.

Green turtles (Chelonia mydas) swim from foraging grounds along the Brazilian coast to Ascension Island to nest, over 2200 km distant in the middle of the equatorial Atlantic. To test the hypothesis that turtles use wind-borne cues to locate Ascension Island we found turtles that had just completed nesting and then moved three individuals 50 km northwest (downwind) of the island and three individuals 50 km southeast (upwind). Their subsequent movements were tracked by satellite. Turtles released downwind returned to Ascension Island within 1, 2 and 4 days, respectively. By contrast, those released upwind had far more difficulty in relocating Ascension Island, two eventually returning after 10 and 27 days and the third heading back to Brazil after failing to find its way back to the island. These findings strongly support the hypothesis that wind-borne cues are used by turtles to locate Ascension Island.

While the long-distance movements of pelagic vertebrates are becoming known thanks to satellite telemetry, the factors determining their courses have hardly been investigated. We have analysed the effects of oceanographic factors on the post-nesting movements of three satellite-tracked leatherback turtles (Dermochelys coriacea) moving in the southwest Indian Ocean. By superimposing the turtle tracks on contemporaneous images of sea-surface temperatures and sea height anomalies, we show that currentrelated features dominate the shape of the reconstructed routes. After an initial offshore movement, turtles moved along straight routes when in the core of the current, or executed loops within eddies. Large parts of the routes were strikingly similar to those of surface drifters tracked in the same region. These findings document that long-lasting oceanic movements of marine turtles may be shaped by oceanic currents.

Loggerhead turtles (Caretta caretta) are known to migrate towards fixed, individually-specific residential feeding grounds. To study their spatial behaviour and their navigational ability, five loggerheads nesting in South Africa were captured when about to start their postnesting migration and tracked by satellite after having been displaced from their usual migratory route. The first turtle, released south of Madagascar about 1,148 km from the capture site, moved west up to mainland Africa and then reached her feeding grounds by following the coast. A second turtle, released farther away (2,140 km) close to La Réunion Island, stopped for some time on the Madagascar east coast, then turned southwards to round the island and regain the African mainland in the northwest, without however allowing us to establish the location of her residential grounds. Three other turtles were released off the Tanzanian coast, 2,193 km north of their nesting area, at the northern edge of the distribution of the feeding grounds along the African coast. All of them headed north, and one turtle found her residential grounds located north of the release site. The other two females started long-distance oceanic wanderings in which they crossed nearly the entire Indian Ocean, apparently being transported by the sea currents of the region. We conclude that adult loggerhead turtles are apparently unable to compensate for the displacement and can return to a pelagic life style characteristic of juvenile turtles. These findings suggest that South African loggerheads rely on simple orientation mechanisms, such as the use of the coastline, as a guide, and compass orientation, possibly integrated by spatiotemporal programmes and/or acquired maps of familiar sites.

Sea turtles are known to perform long-distance, oceanic migrations between disparate feeding areas and breeding sites, some of them located on isolated oceanic islands. These migrations demonstrate impressive navigational abilities, but the sensory mechanisms used are still largely unknown. Green turtles breeding at Ascension Island perform long oceanic migrations (> 2200 km) between foraging areas along the Brazilian coast and the isolated island. By performing displacement experiments of female green turtles tracked by satellite telemetry in the waters around Ascension Island we investigated which strategies most probably are used by the turtles in locating the island. In the present paper we analysed the search trajectories in relation to alternative navigation strategies including the use of global geomagnetic cues, ocean currents, celestial cues and wind. The results suggest that the turtles did not use chemical information transported with ocean currents. Neither did the results indicate that the turtles use true bi-coordinate geomagnetic navigation nor did they use indirect navigation with respect to any of the available magnetic gradients (total field intensity, horizontal field intensity, vertical field intensity, inclination and declination) or celestial cues. The female green turtles successfully locating Ascension Island seemed to use a combination of searching followed by beaconing, since they searched for sensory contact with the island until they reached positions NW and N of the Island and from there presumably used cues transported by wind to locate the island during the final stages of the search.

Satellite telemetry was used to record the submergence duration of green turtles (Chelonia mydas) as they migrated from Ascension Island to Brazil (N=12 individuals) while time/depth recorders (TDRs) were used to examine the depth distribution and dive profiles of individuals returning to Ascension Island to nest after experimental displacement (N=5 individuals). Satellite telemetry revealed that most submergences were short (<5 min) but that some submergences were longer (>20 min), particularly at night. TDRs revealed that much of the time was spent conducting short (2-4 min), shallow (approximately 0.9-1.5 m) dives, consistent with predictions for optimisation of near-surface travelling, while long (typically 20-30 min), deep (typically 10-20 m) dives had a distinctive profile found in other marine reptiles. These results suggest that green turtles crossing the Atlantic do not behave invariantly, but instead alternate between periods of travelling just beneath the surface and diving deeper. These deep dives may have evolved to reduce silhouetting against the surface, which would make turtles more susceptible to visual predators such as large sharks.

Albatrosses and sea turtles are known to perform extremely long-distance journeys between disparate feeding areas and breeding sites located on small, isolated, oceanic islands or at specific coastal sites. These oceanic journeys, performed mainly over or through apparently featureless mediums, indicate impressive navigational abilities, and the sensory mechanisms used are still largely unknown. This research used three different approaches to investigate whether bi-coordinate navigation based on magnetic field gradients is likely to explain the navigational performance of wandering albatrosses in the South Atlantic and Indian Oceans and of green turtles breeding on Ascension Island in the South Atlantic Ocean. The possibility that magnetic field parameters can potentially be used in a bi-coordinate magnetic map by wandering albatrosses in their foraging area was investigated by analysing satellite telemetry data published in the literature. The possibilities for using bi-coordinate magnetic navigation varied widely between different areas of the Southern Oceans, indicating that a common mechanism, based on a bi-coordinate geomagnetic map alone, was unlikely for navigation in these areas. In the second approach, satellite telemetry was used to investigate whether Ascension Island green turtles use magnetic information for navigation during migration from their breeding island to foraging areas in Brazilian coastal waters. Disturbing magnets were applied to the heads and carapaces of the turtles, but these appeared to have little effect on their ability to navigate. The only possible effect observed was that some of the turtles with magnets attached were heading for foraging areas slightly south of the control turtles along the Brazilian coast. In the third approach, breeding female green turtles were deliberately displaced in the waters around Ascension Island to investigate which cues these turtles might use to locate and return to the island; the results suggested that cues transported by wind might be involved in the final stages of navigation.

Previous studies have shown that for some populations of marine turtle, individuals move along narrow migration corridors in the open ocean. It has been suggested that these migration corridors may correspond with near-surface oceanographic features that can be detected by remote sensing. This idea is examined by superimposing the tracks of green turtles (Chelonia mydas) migrating from Ascension Island to Brazil, on sea surface temperature (SST) data derived from Advanced Very High Resolution Radiometer (AVHRR) images. The turtles did not follow specific isotherms during migration nor make turns en-route where specific thermal cues were encountered. These results suggest that for this population, SST plays a minimal role in influencing the exact route that individuals follow.