1,721,099 research outputs found
Analysis of the Kestrel's (_Falco tinnunculus_) predatory behaviour toward rodents
No full textThe predatory behaviour of the Kestrel (Falco tinnunculus) was investigated in detail. I focused particularly on the behavioural sequence displayed by the raptor when catching the prey, the technique used to capture and kill the prey itself, and the causes of death.
Although many researchers have been studying the predatory behaviour for several decades and from different points of view, little is known about the killing method. Previous studies by the author suggested that the prey (a mouse) received repeated bill pecks, particularly on the head region, but that talons were apparently not used at all. It was then hypothesized that death was caused by suffocation and not by the possible wounds.
The tests were performed in captivity in a 4.30 x 2.60 m aviary equipped with a perch and a small table in the middle, where the prey was put for the test. The aviary was located at the Raptor Recovery Centre of Parma, managed by L.I.P.U. All the seven Kestrels used were wild individuals. They were tested when in good condition, at the end of the recovery period and immediately before release.
The birds were tested individually and were offered a prey that was alternately a laboratory mouse (Mus domesticus) of 12-15 g and a laboratory rat (Rattus norvegicus) of 48-60 g, in order to maintain a body weight ratio of 1:4. Such a difference could show variations in the use of pecks and talons in relation to the size, and thus strength, of the prey. In fact, it was expected that the pecks would be more frequent against the bigger prey in order to counteract its greater struggle to escape, and that the talons would be used with equal frequency for killing or, possibly, with lower frequency against the mouse, the smaller prey.
The rat received a much higher (P < 0.001) mean frequency of pecks than the mouse (37.2 ñ 5.8 vs 5.2 ñ 0.8) suggesting that the they are used principally as an aid for prey blocking. In fact, the pecks were mostly directed against the base of the head and the ocular region. By damaging the central nervous system they help to reduce further movement and attempts to escape, particularly when a large and strong prey is caught. Moreover, when the Kestrel preyed upon the rat, it took a significantly (P < 0.001) longer time to begin ingestion (302.7 ñ 75.1 vs 58.3 ñ 7.0). During that period, the bird remained almost motionless, except for the occasional bill pecks, and never lost contact with the prey, continuing instead to clasp it with the foot. The duration is probably because the rat died more slowly, and is indirect evidence that the Kestrel used only foot pressure and not the talons to kill its prey.
Sometimes the prey (15 mice and 13 rats) was removed after death and before ingestion, in order to carry out a necropsy. Such analysis revealed only one animal with a superficial wound from talons. In contrast, clear evidence of alterations related to suffocation were always recorded: large pleural petechiae, enlargement of coronary arteries, prolonged blood fluidity.
In conclusion, the behaviour of Kestrels after catching prey is clearly influenced by the prey size. The absence of talon use is confirmed and moreover the killing technique does not seem to be as specialized as is the capture technique
Footedness bias in hunting birds of prey.
No full textBirds of prey use their feet to hunt prey, particularly when occurring on the ground, and they are good candidates for studies on footedness, i.e. the preferential use of limbs. This preference is still poorly known among birds in general. Several successful attempts at predation by rehabilitated Falconiformes and Strigiformes were analysed
Vertebrate Life (Fifth Edition)
No full textThis new and welcome textbook is a rather great improvement of the previous two editions (1989 and 1996), the older of which was also used to print the present Italian translation (Biologia evolutiva e comparata dei vertebrati, Casa Editrice Ambrosiana, Milano, 1983). This fifth edition is a clear step forward in the improvement of the subject, although the book's general organisation is basically unmodified. The substitution of one of the three authors that signed the four preceding editions was a potential negative aspect, considering those good texts, but, as far as I can understand, such a change does not affect the quality at all
Post-release survival of unnecessarily captive reared owlets
No full textNowadays human activity is a major threat to wildlife. Birds of prey are particularly affected due to their location at the top of trophic pyramids and to their low numbers. Ethical and ecological considerations have led to the development of programmes to treat birds with injuries at Rehabilitation Centres (RC) and their later release back into the wild. This paper deals with a crucial aspect of that programme: the survival success of birds of prey after such release. In recent years an increasing number of orphaned but uninjured Strigiform fledglings entered the RC near Parma. Most of these are collected by people from the base of trees because they have fallen either from the nest or when learning to fly. The fledglings are generally attended by parents but people believe they are injured or abandoned and need help to survive from predators. Such human behaviour is a consequence of the Italian people's increasing concern for animal species. As a result, a large number of young owlets are unnecessarily captive reared and this is potentially affecting negatively their post-release survival in the wild. In a first study a sample of 7 young long-eared owls (Asio otus) was studied after release. The owlets remained very close to the release site (less than 1700 m) and did not avoid human settlements. They increased their distance from the release site, but their survival rate was very low; in fact, 3 birds died within a few days. A second study analyzed a sample of young tawny-owls (Strix aluco) released in a woody area. In contrast to long-eared owlets they were more reluctant to move away from the release site, had smaller home ranges, and their survival rate was higher. The results show how rehabilitation of birds of prey is very important to aid recovery from injures, but is almost useless if not accomplished by good monitoring and surveillance of individuals after release into the wild
Social rank and differences in the feeding behaviour of sows
No full textDuring a previous study (CSERMELY & WOOD-GUSH 1986) concerning the agonistic behaviour of sows, it was noted that dominant animals were very intolerant towards penmates when feeding. This led us to hypothesize that rank could affect feeding behaviour among these animals, with possible differences in the time spent for feeding and for food intake as well
Behavioural and productive aspects among intensively bred piglets
No full textIn modern intensive husbandry one of the most used techniques for increased animal production is the acceleration of weaning. In the pig (_Sus scrofa_ L.) this happens generally at the age of 3-4 weeks post-partum and the young are kept in flat-deck cages. The cages represent a great advantage from the sanitary point of view in comparison to the traditional husbandry, but they are related to frequent occurrences of anomalous behaviours (Van Putten & Dammers, 1976)
La riabilitazione dei rapaci e aspetti comportamentali dopo la liberazione
No full textA causa delle crescenti interazioni che l'uomo ha con la fauna selvatica sono sorti recentemente numerosi Centri di Recupero per i rapaci, con l'obiettivo di curare e successivamente liberare in ambiente naturale il gran numero di Falconiformi e Strigiformi che vengono ricoverati ogni anno. Questo contributo mira a focalizzare sia l'attenzione sugli aspetti riabilitativi che possono influenzare il comportamento dei rapaci durante la cattività, sia l'attività degli individui una volta liberati
Locomotor activity in newborn mice: II. Existence and influence of a male pheromone
No full textIn a previous paper it was observed how locomotor activity of newborn mice raised by both parents decreases significantly compared with that shown by young raised by the mother alone. In the present experiment the sire’s presence was simulated by placing near the nest urine from adult males. In this way, it was possible to note that male urine has the same effect on infant activity as the father’s presence. So, for the first time, the existence of a masculine pheromone, which acts in the parental situation and which influences the litter from birth, is revealed. Its function is evident: to maintain the family cohesion, limiting the activity of the newborn mice
Agonistic behaviour in grouped sows. II. How social rank affects feeding and drinking behaviour
No full textGroups of sows housed in pens with concrete floor were observed to detect differences in feeding and drinking behaviour between animals of high- and low-rank. Dominant individuals remained at the centre of the mash pile defending the food against other animals. The total time spent feeding was similar in high- and low-ranking sows. However, the high ranking sows interrupted feeding more often; subordinates stopped feeding for longer periods because they retreated from attacks. As the mash began to disappear the low-ranking sows resisted the dominants' attacks and refused to leave the feeding area. Drinking behaviour was very frequent in subordinate sows in the early minutes of the meal; this is probably a redirected behaviour resulting from the frustration of being not able to feed continuously
Forme di lateralizzazione motoria negli uccelli rapaci
No full textDiversi taxa di uccelli sono stati studiati per accertare la presenza di lateralizzazione. Tuttavia, gli uccelli rapaci sono stati trascurati, nonostante siano buoni candidati da questo punto di vista, in quanto molte specie rimanendo su un posatoio scrutano il terreno attorno ad esse per cercare potenziali prede. Esse, inoltre, catturano prede terrestri con le zampe, avendo nello stesso tempo la necessità di mantenere l’equilibrio stando in piedi. Questo studio ha cercato di mettere in evidenza, pertanto, l’esistenza di forme di lateralizzazione motoria in tre specie di Falconiformi e quattro di Strigiformi, temporaneamente in cattività per riabilitazione. Sono stati compiuti due esperimenti, in cui si è analizzato (a) la direzione della rotazione del corpo alla percezione di un suono sconosciuto prodotto alle spalle del rapace e (b) l’eventuale uso preferenziale delle zampe nella cattura di una preda terrestre. La lateralizzazione è stata chiaramente presente in entrambi gli esperimenti, sebbene con qualche differenza di esplicazione fra le specie. Infatti, quasi tutte le specie hanno ruotato il corpo in senso antiorario alla percezione del suono, sia nel primo test sia nei successivi, in particolar modo il gheppio (Falco tinnunculus) (P < 0,01). L’afferramento della preda ha mostrato un diverso uso delle zampe nei due taxa. I Falconiformi hanno costantemente preferito (P < 0,05) utilizzare una sola zampa, generalmente la destra, mentre gli Strigiformi entrambe (P < 0,05), sebbene una frazione consistente di individui abbia usato una sola zampa. Solamente la civetta (Athene noctua) ha avuto la tendenza a usare solo una zampa, in modo simile ai Falconiformi. Fra gli Strigiformi studiati, la civetta è la specie più ‘diurna’, suggerendo che la lateralizzazione nell’afferrare la preda possa essere più il risultato di adattamento che una sinapomorfia. La lateralizzazione sembra, pertanto, ampiamente diffusa negli uccelli rapaci. Anche l’uso preferenziale della zampa destra per afferrare sembra una tendenza comune, probabilmente connesso con un dimostrato uso negli uccelli dell’emisfero sinistro per la manipolazione del cibo
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