Homing abilities of lizards after experimental dislocations have been found to be well developed in several species. Following our preliminary findings in Podarcis siculus, the present paper reports a new series of experiments on homing performances and initial orientation behaviour upon release. For this purpose, three series of releases were performed at increasing distances from the home areas in which the lizards were captured (range 85-245 m). In each series, two groups of lizards were released: the route-based visual cues during displacement were denied to one of them (NVIS), but allowed for the other (YVIS). The results of initial orientation showed that both are significantly homeward oriented at all three distances tested. Male and female YVIS and female NVIS are similarly homeward oriented, while the male NVIS are not. All 74 lizards successfully returned to their respective home areas. Eleven lizards homed on the same day they were released, while most of them homed during the 1st day after release (n = 51) and the rest on the 2nd day (n = 12). The different transport treatments did not influence homing success at the different distances tested. These results seem to support the use of a geocentric pilotage strategy to re-enter home from the release spot. Alternatively, the possibility that P. siculus use a sun compass and a mosaic map to find their way home is also discussed.

3 Yaarit Adamovich Charles Allen Ioannis Androulakis Nicola Barclay David Bechtold Eric Bittman Guy Bloch Diane Boivin Steven Brown Timothy Brown Michael Brunner Martin Bulla Brian Cade Alexandra Castillo-Ruiz M. Fernanda Ceriani Etienne Challet Patrick Chappell Evan Chinoy Joanna Chiu Amy Cochran Christopher Colwell Andrew Coogan Claudia Coomans Sarah Coseo-Markt Rodolfo Costa Stephanie Crowley Robert Dallmann Frederick Davis Maaike de Jong Horacio de la Iglesia Tom DeBoer Charna Dibner Derk-Jan Dijk Aaron Dinner Jeanne Duffy Jay Dunlap Jeffrey Elliott Carolina Escobar Rose Faghih Mariana Figueiro Dorothee Fischer Augusto Foa Laura Fonken Daniel Forger Loning Fu Taro Fuchikawa Virginie Gabel Andrew Gall Karen Gamble Marta Garaulet Julie Gibbs Shubhroz Gill Marina Giménez Diego Golombek Yoav Gothilf Rachel Green Claude Gronfier Janne Grønli Mario Guido Jens Hannibal Paul Hardin Stacey Harmer Jeffrey Haspel Marc Hébert Gerhard Heldmaier Charlotte Helfrich-Förster Barbara Helm Jon Vidar Helvik Hanspeter Herzel Erik Herzog Jacob Hughey Roelof Hut Krista Ingram Heiko Jansen Carl Johnson Myriam Juda Andries Kalsbeek Ilia Karatsoreos Thomas Kilduff Kristin Knutson Gladys Ko Nobuya Koike Roman Kondratov Achim Kramer Noga Kronfeld-Schor Shinsuke Kutsuna Charalambos Kyriacou Emma Laing Katja Lamia Edward Large Luis Larrondo Ruta Lasauskaite Choogon Lee Tanya Leise Jonathan Lipton Emily Manoogian C. Robertson McClung Andrew McHill Douglas McMahon Johanna Meijer Martha Merrow Eric Mintz Ralph Mistlberger Stefanie Monecke Jennifer Morton Vincenzo Muto Dawn Nagel Raymond Najjar Jesper Nielsen Phillipp Novotny Hideharu Numata Antonio Nunez Yasukazu Okada Henrik Oster Terry Page Ståle Pallesen Carrie Partch Julie Pendergast Mark Perelis Violetta Pilorz Michael Prerau Jeffrey Price David Ray Amy Reynolds Francois Rouyer Thomas Ruf 829942JBRXXX10.1177/0748730419829942 research-article2019

Disoriented humans and animals are able to reorient themselves using environmental geometry (“metric properties” and “sense”) and local features, also relating geometric to non-geometric information. Here we investigated the presence of these reorientation spatial skills in two species of blind cavefish (Astyanax mexicanus and Phreatichthys andruzzii), in order to understand the possible role of extra-visual senses in similar spatial tasks. In a rectangular apparatus, with all homogeneous walls (geometric condition) or in presence of a tactilely different wall (feature condition), cavefish were required to reorient themselves after passive disorientation. We provided the first evidence that blind cavefish, using extra-visual systems, were able i) to use geometric cues, provided by the shape of the tank, in order to recognize two geometric equivalent corners on the diagonal, and ii) to integrate the geometric information with the salient cue (wall with a different surface structure), in order to recover a specific corner. These findings suggest the ecological salience of the environmental geometry for spatial orientation in animals and, despite the different niches of adaptation, a potential shared background for spatial navigation. The geometric spatial encoding seems to constitute a common cognitive tool needed when the environment poses similar requirements to living organisms.

Quantitative abilities have been reported in many animal species. Two main methods have been extensively used: spontaneous choice tests and training procedures. A recent study showed that ruin lizards are capable of spontaneously discriminating between the surface area of two food items of different size, but failed when food was presented in sets of discrete items differing in number. In the present study, we used a training procedure to further investigate quantitative abilities in ruin lizards. Subjects were presented with two sets of yellow disks differing either in number (Experiment 1) or in area (Experiment 2) and were trained on different discriminations of increasing difficulty (1 vs. 4, 2 vs. 4, and 2 vs. 3). Results showed that lizards were more accurate in discriminating sets of discrete items differing in number than the area of two individual items, in contrast to what had earlier been observed in spontaneous choice tests. Although we cannot exclude other factors that affected the performance of ruin lizards, the poor accuracy here observed in both experiments might reflect a true limit in lizards’ quantitative abilities.

The ability to identify the largest amount of prey available is fundamental for optimizing foraging behaviour in several species. To date, this cognitive skill has been observed in all vertebrate groups except reptiles. In this study we investigated the spontaneous ability of ruin lizards to select the larger amount of food items. In Experiment 1, lizards proved able to select the larger food item when presented with two alternatives differing in size (0.25, 0.50, 0.67 and 0.75 ratio). In Experiment 2 lizards presented with two groups of food items (1 versus 4, 2 versus 4, 2 versus 3 and 3 versus 4 items) were unable to select the larger group in any contrast. The lack of discrimination in the presence of multiple items represents an exception in numerical cognition studies, raising the question as to whether reptiles’ quantitative abilities are different from those of other vertebrate groups.

The ability to identify the largest amount of prey available is fundamental for optimizing foraging behaviour in several species. To date, this cognitive skill has been observed in all vertebrate groups except reptiles. In this study we investigated the spontaneous ability of ruin lizards to select the larger amount of food items. In Experiment 1, lizards proved able to select the larger food item when presented with two alternatives differing in size (0.25, 0.50, 0.67 and 0.75 ratio). In Experiment 2 lizards presented with two groups of food items (1 versus 4, 2 versus 4, 2 versus 3 and 3 versus 4 items) were unable to select the larger group in any contrast. The lack of discrimination in the presence of multiple items represents an exception in numerical cognition studies, raising the question as to whether reptiles' quantitative abilities are different from those of other vertebrate groups.

Exposure of the chick embryo to different wavelengths of light of the same intensity has shown that only certain wavelengths may be important in generating visual asymmetries. This study aimed to detect the possible influence of different wavelengths of light on development of asymmetry of social recognition in zebrafish larvae, tested using the fish's mirror image as the stimulus. From fertilization until day 10 post-hatching zebrafish were kept in five different lighting conditions: natural light/dark (LD) cycle, complete darkness (DD), and artificial LD cycles with 14 h of monochromatic light (red, green, or violet light) and 10 h of darkness (rLD 14:10, gLD 14:10, vLD 14:10, respectively). On day 10 after hatching, the zebrafish larvae were subjected to a mirror test. A preference for using the left eye to scrutinize their mirror image was apparent only in zebrafish larvae exposed to and reared under a natural LD cycle, and not following exposure to any of other lighting conditions. These results are discussed with reference to other evidence of brain lateralization.

Over a decade of comparative studies, researchers have found that rudimentary numerical abilities are widespread among vertebrates. While experiments in mammals and birds have employed a variety of stimuli (visual, auditory and tactile), all fish studies involved visual stimuli and it is unknown whether fish can process numbers in other sensory modalities. To fill this gap, we studied numerical abilities in Phreatichthys andruzzii, a blind cave-dwelling species that evolved in the phreatic layer of the Somalia desert. Fish were trained to receive a food reward to discriminate between two groups of objects placed in opposite positions of their home tank. In Experiment 1, subjects learned to discriminate between two and six objects, with stimuli not controlled for non-numerical continuous variables that co-vary with numbers, such as total area occupied by stimuli or density. In Experiment 2, the discrimination was two versus four, with half of the stimuli controlled for continuous quantities and half not controlled for continuous quantities. The subjects discriminated only the latter condition, indicating that they spontaneously used non-numerical information, as other vertebrates tested in similar experiments. In Experiments 3 and 4, cavefish trained from the beginning only with stimuli controlled for continuous quantities proved able to learn the discrimination of quantities based on the sole numerical information. However, their numerical acuity was lower than that reported in other teleost fish tested with visual stimuli.

Most passerine birds are nocturnal migrants. When kept in captivity during the migratory periods, these species show a migratory restlessness, or Zugunruhe. Recent studies on Sylvia warblers have shown that Zugunruhe is an excellent proxy of migratory disposition. Passerine birds can use the Earth's geomagnetic field as a compass to keep their course during their migratory flight. Among the candidate magnetoreceptive mechanisms are the cryptochromes, flavoproteins located in the retina that are supposed to perceive the magnetic field through a light-mediated process. Previous work has suggested that expression of Cryptochrome 1 (Cry1) is increased in migratory birds compared with non-migratory species. Here we tested the hypothesis that Cry1 expression depends on migratory status. Blackcaps Sylvia atricapilla were caught before fall migration and held in registration cages. When the birds were showing robust Zugunruhe, we applied a food deprivation protocol that simulates a long migratory flight. When the birds were refed after 2 days, their Zugunruhe decreased substantially, as is expected from birds that would interrupt migration for a refuelling stopover. We found that Cry1 expression was higher at night than during daytime in birds showing Zugunruhe, whereas in birds that underwent the fasting-and-refeeding protocol and reduced their levels of Zugunruhe, night Cry1 expression decreased to daytime levels. Our work shows that Cry1 expression is dependent on the presence of Zugunruhe and not on species-specific or seasonal factors, or on the birds being active versus inactive. These results support the hypothesis that cryptochromes underlie magnetoreceptive mechanisms in birds.

The present investigation was aimed at testing whether the lizard sky polarization compass is time compensated. For this purpose, ruin lizards, Podarcis sicula, were both trained and tested for orientation inside a Morris water maze under clear skies with the sun not in view. During training, lizards showed a striking bimodal orientation along the training axis, demonstrating their capability of determining the symmetry plane of the sky polarization pattern and thus the use of polarization information in orientation. After reaching criteria, lizards were kept 7 days in a 6-h fast clock-shift treatment and then released with the sun not in view. Six-hour clock-shifted lizards showed a bimodal distribution of directional choices, which was oriented perpendicularly to the training axis, as it was expected on the basis of the clock-shift. The results show that the only celestial diurnal compass mechanism that does not need a direct vision of the sun disk (i.e., the sky polarization compass) is a time-compensated compass.

SUMMARY Some observations have been made on foraging flights of a colony of rock pigeons in North-West Sardinia. The birds made daily flights of distances up to about 20 km. Homing experiments have been conducted on rock pigeons coming from two different demes. The birds used were born and bred in captivity in two separate lofts (Amino, near Pisa; and Rome). The results show that for distances up to approximately 10 km, the homing performances are not very inferior to those of the homing pigeons of the control group. From greater distances (15–80 km) the rock pigeons performed worse, with long re-entry times (days or weeks) and higher losses with respect to the control group. Some rock pigeons, however, had good performances even at considerable distances with re-entry from up to about 80 km. At the release site the rock pigeons desplayed a tendency to land, often after having flown more or less extensively over the release site itself. However, in those cases in which they took off immediately after the ...

The present study first examined whether ruin lizards, Podarcis sicula, are able to orientate using plane-polarized light produced by an LCD screen. Ruin lizards were trained and tested indoors, inside a hexagonal Morris water maze positioned under an LCD screen producing white polarized light with a single E-vector, which provided an axial cue. White polarized light did not include wavelengths in the UV. Lizards orientated correctly either when tested with E-vector parallel to the training axis or after 90 deg rotation of the E-vector direction, thus validating the apparatus. Further experiments examined whether there is a preferential region of the light spectrum to perceive the E-vector direction of polarized light. For this purpose, lizards reaching learning criteria under white polarized light were subdivided into four experimental groups. Each group was tested for orientation under a different spectrum of plane-polarized light (red, green, cyan and blue) with equalized photon flux density. Lizards tested under blue polarized light orientated correctly, whereas lizards tested under red polarized light were completely disoriented. Green polarized light was barely discernible by lizards, and thus insufficient for a correct functioning of their compass. When exposed to cyan polarized light, lizard orientation performances were optimal, indistinguishable from lizards detecting blue polarized light. Overall, the present results demonstrate that perception of linear polarization in the blue is necessary - and sufficient - for a proper functioning of the sky polarization compass of ruin lizards. This may be adaptively important, as detection of polarized light in the blue improves functioning of the polarization compass under cloudy skies, i.e. when the alternative celestial compass based on detection of the sun disk is rendered useless because the sun is obscured by clouds.

The circadian clock is synchronized with the day-night cycle primarily by light. Fish represent fascinating models for deciphering the light input pathway to the vertebrate clock since fish cell clocks are regulated by direct light exposure. Here we have performed a comparative, functional analysis of the circadian clock involving the zebrafish that is normally exposed to the day-night cycle and a cavefish species that has evolved in perpetual darkness. Our results reveal that the cavefish retains a food-entrainable clock that oscillates with an infradian period. Importantly, however, this clock is not regulated by light. This comparative study pinpoints the two extra-retinal photoreceptors Melanopsin (Opn4m2) and TMT-opsin as essential upstream elements of the peripheral clock light input pathway.

Zeitschrift für TierpsychologieVolume 54, Issue 4 p. 327-338 Does Familiarity with the Release Site Influence the Initial Orientation of Homing Pigeons? Experiments with Clock-shifted Birds Dr. AUGUSTO FOÀ, Corresponding Author Dr. AUGUSTO FOÀ Istituto di Biologia Generale dell'Università di PisaMax-Planck-Institut für Verhaltensphysiologie, D-8131 Seewiesen.Search for more papers by this authorEMANUELA ALBONETTI, EMANUELA ALBONETTI Istituto di Biologia Generale dell'Università di PisaSearch for more papers by this author Dr. AUGUSTO FOÀ, Corresponding Author Dr. AUGUSTO FOÀ Istituto di Biologia Generale dell'Università di PisaMax-Planck-Institut für Verhaltensphysiologie, D-8131 Seewiesen.Search for more papers by this authorEMANUELA ALBONETTI, EMANUELA ALBONETTI Istituto di Biologia Generale dell'Università di PisaSearch for more papers by this author First published: January‐December 1980 https://doi.org/10.1111/j.1439-0310.1980.tb01249.xCitations: 24AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Experiments were performed to test whether the familiarity with the release site plays a role in the initial orientation of homing pigeons. Repeated releases of 6 h clock-shifted birds from the same site during the shifting time produced an improvement of their initial orientation: the shift effect decreased progressively. Since in subsequent releases from unfamiliar sites the shift effect reappears, the course correction observed at the familiar site is attributable to local stimuli and not to a general recalibration of the sun compass. Citing Literature Volume54, Issue4January‐December 1980Pages 327-338 RelatedInformation

The present study first examined whether ruin lizards Podarcis sicula are able to orientate using the e-vector direction of polarized light. Ruin lizards were trained and tested indoors, inside a hexagonal Morris water maze, positioned under an artificial light source producing plane polarized light with a single e-vector, which provided an axial cue. Lizards were subjected to axial training by positioning two identical goals in contact with the centre of two opposite side walls of the Morris water maze. Goals were invisible because they were placed just beneath the water surface, and water was rendered opaque. The results showed that the directional choices of lizards meeting learning criteria were bimodally distributed along the training axis, and that after 90 deg rotation of the e-vector direction of polarized light the lizards directional choices rotated correspondingly, producing a bimodal distribution which was perpendicular to the training axis. The present results confirm in ruin lizards results previously obtained in other lizard species showing that these reptiles can use the e-vector direction of polarized light in the form of a sky polarization compass. The second step of the study aimed at answering the still open question of whether functioning of a sky polarization compass would be mediated by the lizard parietal eye. To test this, ruin lizards meeting learning criteria were tested inside the Morris water maze under polarized light after their parietal eyes were painted black. Lizards with black-painted parietal eyes were completely disoriented. Thus, the present data show for the first time that the parietal eye plays a central role in mediating the functioning of a putative sky polarization compass of lizards.

SUMMARY The present study examined for the first time whether a Morris water-maze can be used to explore compass and other orientation mechanisms in the ruin lizard Podarcis sicula. In the open field, during sunny days, lizards were individually trained to swim from the center of the water maze onto a hidden platform (the goal), positioned at the periphery of the maze in a single compass direction. The goal was invisible because it was placed just beneath the water surface and the water was rendered opaque. The results showed that lizards learn to swim directly towards the hidden goal under the sun in the absence of visual feature cues. We further examined whether the observed orientation response would be due to lizards learning the spatial position of the goal relative to the sun's azimuth, i.e. to the use of a time-compensated sun compass. Lizards reaching learning criteria were subjected to 6 h clock-shift (fast or slow), and tested for goal orientation in the Morris water-maze. Results demonstrated that the learned orientation response is mediated by a time-compensated sun compass. Further investigations provided direct evidence that in ruin lizards an intact parietal eye is required to perform goal orientation under the sun inside a Morris water-maze,and that other brain photoreceptors, like the pineal or deep brain photoreceptors, are not involved in orientation.