GPS tracking technology and re-visiting the relationship between the avian visual Wulst and homing pigeon navigation

Within their familiar areas homing pigeons rely on familiar visual landscape features and landmarks for homing. However, the neural basis of visual landmark-based navigation has been so far investigated mainly in relation to the role of the hippocampal formation. The avian visual Wulst is the telencephalic projection field of the thalamofugal pathway that has been suggested to be involved in processing lateral visual inputs that originate from the far visual field. The Wulst is therefore a good candidate for a neural structure participating in the visual control of familiar visual landmark-based navigation. We repeatedly released and tracked Wulst-lesioned and control homing pigeons from three sites about 10-15 km from the loft. Wulst lesions did not impair the ability of the pigeons to orient homeward during the first release from each of the three sites nor to localise the loft within the home area. In addition, Wulst-lesioned pigeons displayed unimpaired route fidelity acquisition to a repeated homing path compared to the intact birds. However, compared to control birds, Wulst-lesioned pigeons displayed persistent oscillatory flight patterns across releases, diminished attention to linear (leading lines) landscape features, such as roads and wood edges, and less direct flight paths within the home area. Differences and similarities between the effects of Wulst and hippocampal lesions suggest that although the visual Wulst does not seem to play a direct role in the memory representation of a landscape-landmark map, it does seem to participate in influencing the perceptual construction of such a map.

Use of the sun compass by monocularly occluded homing pigeons in a food localisation task in an outdoor arena

Functional asymmetries of the avian visual system can be studied in monocularly occluded birds, as their hemispheres are largely independent. Right and left monocularly occluded homing pigeons and control birds under binocular view have been trained in a food localisation task in an octagonal outdoor arena provided with one coloured beacon on each wall. The three groups were tested after the removal of the visual beacons, so to assess their sun compass learning abilities. Pigeons using the left eye/right hemisphere system exhibited slower learning compared to the other monocular group. During the test in the arena void of visual beacons, the three groups of birds, regardless of their visual condition, were generally able to identify the training sector by exclusively relying on sun compass information. However, the directional choices of the pigeons with the left eye/right hemisphere in use were significantly affected by the removal of the beacons, while both control pigeons and birds with the right eye/left hemisphere in use displayed unaltered performances during the test. A subsample of pigeons of each group were re-trained in the octagonal arena with visual beacons present and tested after the removal of visual beacons after a 6 h fast clock-shift treatment. All birds displayed the expected deflection consistent to the sun compass use. While birds using either the left or the right visual systems were equally able to learn a sun compass-mediated spatial task, the left eye/right hemisphere visual system displayed an advantage in relying on visual beacons.

Fecal contamination of urban parks by domestic dogs and tragedy of the commons

Contamination of public parks by dogs is a potential source of conflict among park users, causing "tragedy of the commons" problems. Besides the social conflict, feces can pose serious health risks to both dogs and humans. In this study we analyzed the extent and patterns of the distribution of dog feces in the urban parks of the City of Calgary. We collected dog feces from randomly selected locations in the urban parks. The average density of dog feces by the different dog leash policies of the parks and the distribution pattern of the fecal density within the parks were assessed, and the total contamination of the public parks for the entire city was estimated. We found off-leash parks to be significantly more contaminated than other types of parks. We estimated 127.23 g/ha of dog feces are left unpicked in city parks in total every week. Dog feces were found more often and in greater amount in off-leash parks, and near park entrances and parking lots, than in on-leash parks and away from the park entrances. These results suggest that public park visitors, especially those visiting off-leash parks, are likely to be exposed to large amounts of dog feces. Designation of parks as on-leash and educating dog-owners may be an effective approach for reducing the fecal contamination.

Social Isolation Affects the Mimicry Response in the Use of Smartphones : An Ethological Experiment during the COVID-19 Pandemic

Humans are social animals that rely on different ways to interact with each other. The COVID-19 pandemic strongly changed our communication strategies. Because of the importance of direct contact for our species, we predict that immediately after the forced social isolation, people were more prone to engage in direct rather than in virtual interactions, thus showing a lower mimicry response in the use of smartphones. In a non-longitudinal study, we collected behavioral data under naturalistic contexts and directly compared the data of the mimicry response gathered immediately following the Italian lockdown (May-September 2020) with those gathered one year later (May-October 2021). Contrary to our expectations, the mimicry response in the use of smartphones was higher immediately after the lockdown than a year later. Probably the large use of these devices during the lockdown translated into a greater sensitivity to be affected by others' smartphone manipulation. Indeed, social isolation modified, at least in the short term, the ways we interact with others by making us more prone to engage in "virtual" social interactions. The bright side of the coin unveiled by our findings is that the effect seems to diminish over time. The large behavioral dataset analyzed here (1,608 events; 248 people) also revealed that the mimicry response in the use of smartphones was higher between familiar subjects than between strangers. In this view, mimicry in manipulating smartphones can be considered an example of joint action that fosters behavioral synchrony between individuals that, in the long-term, can translate into the formation of social bonding.

Spatio-temporal inhabitation of settlements by Hystrix cristata L., 1758

Settlements are usually shared at different times by semi-fossorial mammals. Porcupine reproductive pair shows high den-site fidelity, but no data are available on the spatio-temporal inhabitation of settlements. In this investigation, the spatio-temporal inhabitation of settlements by crested porcupine families was investigated using camera-trapping as well as the ethological factors affecting the settlements selection. The crested porcupine resulted to be the main inhabitant of settlements surveyed in the present study. Each settlement was inhabited exclusively by one porcupine family. Five out of six porcupine families, each alternatively and complementarily inhabited the same two settlements. In all the five monitored families, settlements selection doesn’t follow a seasonal pattern. Settlement inhabitation of porcupines resulted positively affected by cohabitation with badger, while presence of porcupettes did not affect settlements selection. Long periods of settlement inhabitation were positively affected both by the presence of porcupettes and cohabitation with badger. The pattern of settlements inhabitation in relation to their availability and porcupine population density as well as factors promoting porcupine-badger cohabitation should be further investigated. New ethological knowledge obtained in this investigation could be involved in the evaluation of the ecological epidemiology of infectious diseases between porcupine and badger within a one health approach and may be a useful tool for a sustainable management of semi-fossorial mammals.

The abundance of yellow-legged gulls Larus michahellis breeding in the historic centre of Venice, Italy and the initial effects of the new waste collection policy on the population

The yellow-legged gull Larus michahellis has undergone widespread colonization of the urban environment in the recent past. The first urban breeding gulls were recorded in the historical centre of Venice, Italy, in 2000, and by 2005 there were already 24 roof-nesting pairs, with this number increasing significantly over the last decade. In 2016, a new door-to-door garbage collection system was introduced in Venice to prevent the accumulation of rubbish in the streets and limit the trophic resources available for the species. This study provides an up-to-date estimate of the Venice yellow-legged gull urban population using distance sampling method. We also studied the effect of the new waste collection system on the species by comparing the population estimate before (2017) and after (2018) the full implementation of this change and by analysing the trend of individuals collected in the old town by the wildlife recovery service during 2010–2018. Results estimated ca. 430 breeding pairs in June 2018 showing a 36% decrease with respect to 2017. We also found a decrease in the number of 1-year-old birds and pulli collected by the wildlife recovery service starting from 2016, when the policy implementation began. Our data did not show a significant decrease in the overall number of individuals, suggesting that the new policy has a stronger effect on the breeding success of the species than on adult survival. This study emphasizes the importance of preventing rubbish accumulation in the streets as factor for reducing the abundance of urban yellow-legged gulls.

Feral pigeon populations: their gene pool and links with local domestic breeds

Columba livia is a wild bird whose domestication has led to a large number of pigeon breeds. The occasional loss or straying of domestic birds determined the origin of feral pigeons, which are now widespread all around the world. In this study, we assumed that the main contribution to feral populations is provided by domestic breeds reared in the same areas. We tested this hypothesis by analysing the variability of 12 microsatellite loci in nine Italian feral populations sampled in areas with different intensities of breeding and selecting domestic breeds. We included in the analysis samples belonging to ten domestic lineages commonly bred in Italy. The pattern of geographic differentiation of feral populations turned out to be rather complex and only partially explained by the geographic distance between populations. This pattern can be understood only when the domestic breeds were included in the analysis. In particular, feral populations located in regions with a long-lasting tradition of pigeon breeding showed a high level of admixture with domestic breeds, in particular with Racing Homer and Piacentino. Ferals from Bolzano, Venice and Sassari were characterized by unique genetic components, mostly not shared by other feral populations and by the considered domestic breeds. Our results further emphasize the complex genetic structure of feral populations whose origin can be properly investigated by taking into account the pool of domestic pigeons bred in the considered area.

Large-scale patterns of genetic variation in a female-biased dispersing passerine: the importance of sex-based analyses

Dispersal affects the distribution, dynamics and genetic structure of natural populations, and can be significantly different between sexes. However, literature records dealing with the dispersal of migratory birds are scarce, as migratory behaviour can notably complicate the study of dispersal. We used the barn swallow Hirundo rustica as model taxon to investigate patterns of genetic variability in males and in females of a migratory species showing sex-biased dispersal. We collected blood samples (n = 186) over the period 2006 to 2011 from adults (H. r. rustica subspecies) nesting in the same breeding site at either high (Ireland, Germany and Russia) or low (Spain, Italy and Cyprus) latitude across Europe. We amplified the Chromo Helicase DNA gene in all birds in order to warrant a sex-balanced sample size (92 males, 94 females). We investigated both uniparental (mitochondrial ND2 gene) and biparental (microsatellite DNA: 10 loci) genetic systems. The mtDNA provided evidence for demographic expansion yet no significant partition of the genetic variability was disclosed. Nevertheless, a comparatively distant Russian population investigated in another study, whose sequences were included in the present dataset, significantly diverged from all other ones. Different to previous studies, microsatellites highlighted remarkable genetic structure among the studied populations, and pointed to the occurrence of differences between male and female barn swallows. We produced evidence for non-random patterns of gene flow among barn swallow populations probably mediated by female natal dispersal, and we found significant variability in the philopatry of males of different populations. Our data emphasize the importance of taking into account the sex of sampled individuals in order to obtain reliable inferences on species characterized by different patterns of dispersal between males and females.

On the use of pharmacological sterilisation to control feral pigeon populations

The use of chemosterilisation for controlling feral pigeon populations was investigated by: (1) quantifying the reproductive activity of pigeons in two Italian cities; (2) testing the efficacy of nicarbazin, an anticoccidial drug with rapid and reversible effects on the reproduction of laying hens, on groups of paired pigeons maintained in open aviaries; and (3) simulating the effects of the use of nicarbazin on a hypothetical population, allowing for the reproductive productivity recorded in (1) and the efficacy of this drug as obtained in (2). Breeding attempts were recorded all year round in both study sites with a minimum peak in September–October, a maximum in March–July, but with active nests in winter too. In terms of the sterility activity of the drug, the results showed only a partial inhibition of reproduction of pigeons fed ~38–82 mg nicarbazin day–1 (kg bodyweight)–1 (500 and 800 ppm in feed), which, according to the simulations, would produce only a fleeting reduction of their abundance in the field. Data do not seem to support the use of this drug as an effective control method for feral pigeons, and they cast doubts on the opportunity to make use of chemosterilants, which produce only partial and reversible effects. The use of this drug could perhaps be considered only as part of an integrated pest-management program, which necessarily has to include the reduction of carrying capacity of the urban environment.

The effect of clock-shift on the initial orientation of wild rock doves ( Columba l. livia)

Previous experiments on wild rock doves ( Columba l. livia Gmelin) released within their familiar area revealed an evident effect of fast-shifting, although shifted doves, but not controls, tended to orient homeward. Such an outcome suggested a possible influence of the release time per se on the directional choices of the tested doves. In the present study, this hypothesis was investigated by comparing the orientation of slow-shifted birds to that of two control groups released at different times of the day. As would be expected if doves make use of a time-compensated sun compass, the bearings of shifted birds were deflected clockwise with respect to controls. The time of release itself seemed to influence only the scatter of the vanishing bearings of controls. These findings testify to the substantial similarity of clock-shift effects on the initial orientation of rock doves to those on homing pigeons released from familiar sites.

RELEASE EXPERIMENTS WITH WILD ROCK DOVES (COLUMBA L. LIVIA GM.)

Abstract

The homing behaviour of free-living birds has rarely been systematically investigated, and so it is difficult to give a satisfactory comparative picture. Data are here presented on the initial orientation of rock doves displaced inside and outside the area that they daily cross during their foraging flights. Inside the familiar area, the results show marked variability in the directional choices of the released birds, probably related to temporal variability in the location of food patches during the year. Indeed, in autumn, when the doves feed almost exclusively near the colony site, they tend to fly home, but in summer, when food patches are dispersed over a wide area around the colony, this behaviour is not evident. Outside the familiar area, no clear evidence of a homeward directedness is obtained. Two releases inside the familiar area with clock-shifted birds produced ambiguous results and it is difficult to attribute the behaviour of the animals to a change in their motivation to reach home in different times of the day, or to the use of a time-compensated sun compass. On the whole, the presented results point to the difficulties of comparing rock dove behaviour to that of the homing pigeon, and show the importance of considering the influence of ecological and motivational variables in evaluating the orienting performances of wild birds.

A LONG TERM STUDY ON INITIAL ORIENTATION IN SAND MARTINS (RIPARIA RIPARIA)

Abstract

Over a period of 18 years sand martins (Riparia riparia) were displaced from their breeding colonies and released to investigate the relationship between distance of displacement and initial orientation. The results show significant homeward orientation at the shortest distances of displacement (7.1-18.2 km, series A), but not over longer distances (49-180 km, series B and C). Birds displaced over 49 km from their breeding colonies only seldom show homeward directedness, while pseudo-pooling and second order analysis of their directional choices seem to indicate the tendency to fly in a given compass direction. Possible causal factors that can induce this behaviour in sand martins are discussed, taking into account not only local biasing factors but also the existence of a so called preferred compass direction. These data show that sand martins are able to determine the correct homing direction inside a probably familiar area. The response over longer distances indicates difficulties in determining the appropriate homing course at takeoff.