Cue-conflict experiments between magnetic and visual cues in dunlin Calidris alpina and curlew sandpiper Calidris ferruginea

Despite our extensive knowledge on various aspects of their lives, there has been limited investigation into the hierarchical relationships among different compass systems in shorebirds. The aim of this study was to investigate the relationship between magnetic and celestial compasses in two species of shorebirds, the curlew sandpiper (Calidris ferruginea; prebreeding migration) and the dunlin (Calidris alpina; postbreeding migration) using cue-conflict experiments. Birds were captured in a Mediterranean stopover site, after which their magnetic orientation was determined under simulated overcast conditions at sunset using modified Emlen funnels fitted with infrared video cameras. Birds that demonstrated a well-defined directional preference were then exposed over two sunsets to conflicting directional information between the local geomagnetic field and the ±90° shifted band of maximum polarisation. These individuals were tested again for magnetic orientation at sunset in the same conditions as previous test, to determine whether their directional choices had changed after the cue-conflict. Our results showed that individuals from both species did not recalibrate their magnetic compass from visual cues after the cue-conflict, even though at least dunlins did not appear to completely disregard the information derived from celestial cues. This study is one of the few experimental studies on the migratory orientation of Charadriiformes and on the hierarchical relationships between the different compasses used by these birds during their extensive migratory movements

Living between widely separated areas: Long-term monitoring of Mediterranean loggerhead turtles sheds light on cryptic aspects of females spatial ecology

Over the last decades, satellite tracking techniques have substantially advanced our understanding of sea turtle spatial behaviour, especially for the post-nesting migrations of females. Substantial gaps remains in our knowledge of the turtle behaviour during the remaining inter-reproductive period, that spans over 2–3 years. We report the results of a prolonged tracking experiment on loggerhead turtles nesting along the Ionian Calabria, the main breeding ground in Italy. Argos satellite transmitters were deployed on eight females, a sample representing a substantial fraction of the overall population (20–25 nesting females). All turtles but one were tracked for > 300 days (range: 313–1523 days), revealing their spatial behaviour during a complete reproductive cycle and providing novel information on a number of poorly-known aspects of loggerhead spatial ecology: i) the post-nesting migratory strategy resulted in accordance with that of most adult loggerheads tracked so far, as the nine routes of six turtles were directed towards specific sites all located in the Tunisian continental shelf, a main foraging area for Mediterranean turtles; ii) the pre-breeding migratory routes were rather variable, likely deriving from different navigational strategies adopted by migrating turtles, and their temporal pattern indicates that mating occurred away from the nesting area; iii) the 10 inter-nesting movements of four turtles revealed unusual long-distance loops mostly in oceanic waters (median of maximum distance from nesting location: 145.5 km); iv) while at the foraging grounds, four turtles occupied distinct areas during summer and winter, making directed movements between the two sites, seasonal core areas were separated and their size was larger in winter than in summer (median: 498 km2 vs. 258 km2); v) individual females displayed an high fidelity to both sites in successive years. These findings further highlight the plasticity in loggerhead spatial behaviour and the importance of the Central Mediterranean and of the Tunisian shelf for loggerhead conservation

A weak individual signature might not allow chick call recognition by parent Stone Curlews Burhinus oedicnemus

Offspring recognition has been confirmed in many bird species, and vocal signatures appear to be its major component. Up to now most studies dealt with colonial species, but recent findings indicate that similar recognition is also present in non-colonial birds. By integrating spectrographic analysis and playback experiments, we investigated for the first time parent–offspring vocal recognition in the Stone Curlew (Burhinus oedicnemus), a highly vocal, crepuscular-nocturnal species that usually rears a maximum of two precocial and nidifugous chicks. Even though the species is usually non-colonial and non-cooperative, in Taro River Regional Park, Parma, Italy, breeding territories are densely packed with distances between simultaneously active nests as close as 40 m, which creates the possibility that chicks might be exchanged. Our analysis identified two main vocalizations in the chick call repertoire: (1) the S-call, a brief strangled soft sound often uttered when parents and chicks were at close quarters; and (2) the C-call, a chirping sound with a complex structure, which seems to be a long-distance contact vocalization. Our acoustic analysis showed that, even though the structure was remarkably different between chicks, C-calls were an unreliable individual signature given their high intra-individual variability. This was confirmed by playback experiments. Indeed, when presented with simulated C-calling chicks, adults approached both their own and foreign chicks with equal responses. These results suggest that parent Stone Curlews are unable to recognize their offspring by voice. Furthermore, experiments are needed to test whether the chicks are able to recognize their parents' voice and, more generally, to understand the details of parent–offspring communication in this species

New cue-conflict experiments suggest a leading role of visual cues in the migratory orientation of Pied Flycatchers Ficedula hypoleuca

Migratory birds use both geomagnetic and celestial cues to select and maintain their seasonally appropriate migratory direction. The integration of the different compass cues is still poorly understood. Previous cue-conflict experiments suggested that Pied Flycatchers Ficedula hypoleuca did not recalibrate their magnetic compass against the polarization pattern at twilight, but the available evidence is problematic given the high variability of birds’ directional preferences. We performed a new set of cue-conflict experiments where (1) we modified the protocol in order to try to reduce scatter of data and (2) we integrated the results of two experimental approaches, i.e. orientation cages and releases of radio-tagged birds. Pied Flycatchers were tested in Emlen funnels without access to celestial cues before and after being exposed to conflicting visual and geomagnetic information. After the second test, birds were equipped with radio-transmitters and followed until the vanishing of the radio signal. Contrary to previous experiments, our data showed a general dominance of celestial cues: polarized light sun-related pattern in captive birds tested without access to stars and stellar dominance in free-flying birds released under a starry sky at night-time. These results underline the importance of experimental protocols when testing ways in which birds integrate their compass systems

Migratory restlessness in shorebirds (Aves, Charadriiformes). A case study by means of accelerometers

The knowledge of individual and environmental parameters affecting stopover length in shorebirds is important for the conservation and management of species and habitats often seriously threatened, such as Mediterranean wetlands. The role of external factors affecting the decision to leave a stopover site is not always easy to study in the field, due to the high number of variables (i.e., atmospheric conditions) potentially involved. Combining both field and laboratory research has proved to be extremely useful in order to identify the main factors affecting stopover length, at least in passerines. Recent studies demonstrated that the amount of migratory restlessness in these species can be considered a good proxy for quantifying the willingness to depart from a refuelling site. Even if shorebirds have proved to be good models for laboratory research, the only papers regarding migratory restlessness in this group concern studies on orientation mechanisms, which are mainly aimed at showing their use of magnetic compass. The present work aims at studying the migratory restlessness in shorebirds and its relation with body conditions and stopover length by using spring migrating Wood sandpiper (Tringa glareola) as a model species. Despite this method proved to be effective in recording Wood sandpipers activity, we failed to found any relationship among their stopover length, body conditions and nocturnal activity. The degree of nocturnal activity was overall low, whereas a peak in activity was registered at sunset. This twilight activity was oriented, and its amount varied significantly according to the amount of available food in captivity. Our results suggested that migratory restlessness in shorebirds might show some peculiar characteristics that would deserve further investigations

Stato sanitario dei colombi della città di Bolzano

I colombi urbani, per il loro stato sinantropico, costituiscono un considerevole rischio sanitario per i cittadini e gli animali con cui vengono in contatto. In questo lavoro vengono riportati i risultati delle analisi fatte a Bolzano sul loro stato sanitario, nel quadro di un progetto di gestione e monitoraggio della locale popolazione di colombi. Le prevalenze di Chlamydiaceae riscontrate nel periodo 2001- 2009 sono sempre risultate elevate, ma in linea con quanto noto in letteratura, sicché è possibile defi nire questo batterio come un ospite stabile del colombo, nonché uno dei maggiori agenti zoonotici. Prevalenze egualmente elevate sono state riscontrate per Toxoplasma gondii. Al contrario non sono stati individuati colombi affetti da salmonellosi e Febbre Q, e del tutto episodici i casi di borreliosi. Le prevalenze di infestazione da larve di Argas refl exus sono risultate diminuite fortemente rispetto agli anni ’90, fatto che con l’assenza di casi di salmonellosi, depone a favore della qualità dell’ambiente bolzanino. Sono state ritrovate cinque specie di parassiti intestinali alcune delle quali con una abbondanza così alta da determinare l’occlusione del dotto intestinale. I risultati sono discussi in vista del rischio che i vari patogeni costituiscono per l’uomo e gli altri animali, con un focus sui fattori potenzialmente responsabili dell’alta occorrenza di Chlamydiacea

Old and novel methods for estimating Feral Pigeons (Columba livia f. domestica) population size: a reply to Amoruso et al. (2013)

In a recent paper Amoruso et al. (2013) proposed a novel method for estimating population size of Feral Pigeons, the Superimposed Urban Strata (SUS) method. In our reply we firstly comment on the lack of a complete review of the available literature. Secondly we point out that the SUS method does not account for birds detection probability and thus it is just a simple index of abundance as many others proposed in recent years. Thirdly, we question the approach used by the authors to evaluate the reliability of their method. To conclude, we believe that the SUS method is not truly innovative and that further investigations are needed before considering it as a reliable way for estimating Feral Pigeons populations size

Multilocus approach reveals an incipient differentiation process in the Stone-curlew, Burhinus oedicnemus around the Mediterranean basin

The Stone-curlew Burhinus oedicnemus, a steppe bird species, is mainly distributed in the Mediterranean and Macaronesian regions, which are considered hotspots of biodiversity with priority for animal and plant species richness conservation. In this study, we investigated the genetic diversity of the Stone-curlew in the Mediterranean basin and in the Canary Islands by applying a multilocus approach. We analysed mitochondrial and nuclear markers in order to evaluate the genetic structure and the congruence between morphological subspecies and geographic samples. We found a significant level of genetic differentiation between Mediterranean and Canary Island populations with all markers. Both in the Mediterranean basin and in the Canary Islands, we found a significant level of genetic diversity with nuclear markers only. We identified seven population groups, including insular populations. The four subspecies described for the Western Palaearctic were confirmed with some changes in distribution range. In spite of habitat fragmentation and negative population trend, the Stone-curlew showed a significant level of genetic diversity and gene flow among continental populations. However, islands constitute important reservoirs of genetic diversity and a potential for the evolution of the species

I colombi della città di Bolzano: interventi di gestione e caratteristiche della popolazione

Il colombo urbano è un’entità prettamente sinantropica che pone continui problemi di convivenza con l’uomo e le sue attività. Il comune di Bolzano ha, fi n dal 1988, avviato un programma di gestione della popolazione di colombi, coordinato da una commissione tecnico-scientifi ca composta da esperti e portatori di interesse. Il programma ha previsto una iniziale caratterizzazione morfologica e comportamentale di questa popolazione, che ha mostrato l’assenza di voli quotidiani di foraggiamento nelle campagne, così che le risorse trofi che sono reperite totalmente nell’ambito urbano. Per il controllo numerico dei colombi sono state sperimentate sia metodologie di cattura e soppressione dei soggetti, che di chemiosterilizzazione. Quest’ultima metodologia, o per l’assenza di risul- tati tangibili o per il gravoso impegno economico, è stata abbandonata dopo l’impiego di prodotti contenenti sia progesterone che nicarbazina come principio attivo. Il modello di gestione attuale è basato: a) sulla quotidiana distribuzione di granaglie in 10 punti fi ssi, dove erano state costruite apposite piazzole di alimentazione; b) sul controllo dello stato sanitario dei colombi, accertato su di un campione percentualmente rappresentativo della popolazione, mediante la cattura di esemplari alle piazzole; c) sul monitoraggio delle dimensioni della popolazione, valutata sia attraverso i conteggi alle piazzole sia con metodologie di stima tramite distance sampling; d) sulla emanazione di ordinanze volte a vietare la distribuzione di cibo da parte dei cittadini e promuovere la difesa degli edifi ci per disincentivare lo stazionamento dei colombi

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