Analele Ştiinţifice ale Universităţii Al. I. Cuza Iaşi, s. Biologie animală, Tom LIV, 2008 INTERACTIONS OF CORVUS FRUGILEGUS (L.) WITH THE KEEPER Emanuel TÂRNOVEANU Al. I. Cuza University Iaşi, Faculty of Biology, Bd. Carol I 20A, 700505 Iaşi, Romania, emantarn@yahoo.com Abstract. The present study follows the development of two rook juveniles (Corvus frugilegus L.) in captivity, beginning with the moment of capture until the moment of alimentary independence. The study is based on the prior behavioural analysis of an examplar of this species raised in isolation from his wild fellows during the summer of 2005. The experiment on C. frugilegus (L.) exemplars was carried out in 2007 concomitantly with observations made in their original colony (Iaşi, Romania). The two subjects, whose age difference is insignificant, were found at 8 days distance, during the phase of the colony occupants dispersion to the neighbouring bushes. By setting them in contact with one another, the present experiment aimed at obtaining data regarding the gregarious behaviour of the species. For the recognition of the behavioural components common to wild and tamed rooks, as well as of the distinctive ones, I have relied on the observations in the colony near The Lord s Entrance in Jerusalem church from Flora-Tătăraşi, on the experiment with exemplars of Corvus frugilegus (L.) raised together (which were wilder), as well as on the experiment conducted in 2005 on a single subject. Keywords: Ethology, Corvus frugilegus (L.), captivity, trophic and defensive relations. Rezumat. Interacţiuni ale orfanilor de Corvus frugilegus (L.) cu îngrijitorul. Studiul interacţiunii dintre puii de C. frugilegus (L.) şi îngrijitor efectuat în 2007 coroborat cu observaţii asupra relaţiilor puilor liberi cu părinţii lor, priveşte componenta afină a comportamentului cerşitului. Afinitatea faţă de subiectul care hrăneşte, omul sau pasărea-părinte, a fost analizată prin practicarea unor observaţii asupra comportamentului juvenil dependentalimentar în condiţii de creştere artificiale, respectiv, naturale. Compararea indivizilor de C. frugilegus (L.) crescuţi împreună în vara anului 2007 cu individul izolat în vara anului 2005 vizează intensitatea comportamentului afin în situaţia exemplarului unic în relaţia cu îngrijitorul, bazată pe hrană şi protecţie. Persistenţa în libertate a comportamentului afin faţă de îngrijitor la exemplarul crescut izolat în 2005 a fost asociată cu imprimarea. Reacţiile defensive şi comportamentul gregar constatate în urma evadărilor repetate ale puilor crescuţi împreună în 2007 au fost puse pe seama labilităţii relaţiei cu omul. Adulţii instituie o relaţie ierarhică superioară faţă de juvenilii crescuţi artificial care le solicită hrană atunci când scapă de sub controlul îngrijitorului sau când sunt lăsaţi să evadeze în chip experimental. Cuvinte cheie: etologie, Corvus frugilegus (L.), captivitate, relaţii trofice şi de apărare. Introduction The study of the rook populations during the breeding season was made in Flora- Tătăraşi area, where the location of the nest underwent some changes in 2007 compared to the previous years. In the spring of 2007, the nests in the trees situated near the stands of the V. Lupu street were occupied by long-eared owls. At the same time, the tree situated near the grocery store near Flux Ferometalice was colonized by a large number of Corvus frugilegus (L.) pairs. At the beginning of the spring, the food scraps from the garbage container located in the above mentioned area represent a food source occasionally used by the rook pairs that maintain a relationship based on the feeding of the female by its partner. The search for food of the sexes as described above stops during the incubation period and during the raising of the chicks, when the transfer of the food is made at the nest (Cătuneanu, 1953). As the breeding season advances, the searches for food done at distance from the colony take the place of those done on the nesting territory, and this situation lasts until the breeding season is over.
Emanuel Târnoveanu The chicks met on the field at the moment of flight preparations represent the object of the comparison done between them and the one captured in order to be recovered. The latter were fed by means of introducing the food in their wide opened bills, as soon as their reflex of begging for hand-feeding appeared. The behaviour of following the keeper could be observed only at the specimen that was raised in isolation in 2005. In the case we are discussing now, an exclusively trophic relation was built between the chicks and their keeper, the specimens having the possibility to continually interact between them by means of an artificial contact induced 8 days after the capturing of the first chick. This type of interrelation, introduced in the experiment because of lack of space (balcony), was also the cause of the defensive behaviour towards man, behaviour opposed to that of imprinting. As opposed to the specimen of 2005, which, once freed, maintained contact with the keeper, the half-wild juveniles of 2007 could not be controlled regarding their coming back to the shelter. However, this fact did not exclude the possibilities of feeding them by hand, after a previous starvation, and of initiating their recovery. The reason for which I met in the breeding season of the rooks in 2007 feebler chicks than in the previous years has to do with the weather condition, which was characterized by dryness. The number of the juveniles that grew up until reaching the independence phase was lesser compared to the previous years. Material and Methods The accessories used in captivity to feed and water the C. frugilegus (L.) chicks were little spoons and syringes, respectively. When hand-feeding the chicks, the food was prepared as a mixture of meat with water and cat food and food for chicken chicks; for sleeping accommodation was used a basket made out of twigs and hung with newspaper, horizontally fixed roosts; for playing were used pieces of synthetical strings, which were also used for tapping; for collecting and removing the excrements were used newspapers placed under the roosts; for bathing was used a basin filled with water up to the level of the tarsi and equipped with a brick needed for helping the bird to achieve balance in the basin; for feeding training was used a cage with fresh collected boughs; for flying exercises was used a temporary device placed on the partially closed balcony mentioned above. The direct study of the C. frugilegus (L.) juvenile orphans was initially made on the spot, depending on where they were after flying from the nest, on the nesting territory or in its immediate proximity. The capture and the hand-feeding followed after an evaluation of possible predators had taken place (dogs, cats). In the first phase the objective was to isolate the subjects from stimuli of the natural environment (the calls of the birds, their alarm at the sight of predators, conflicts among birds etc.), in order to familiarize them with the human presence. In order to watch their movements when training for flying and feeding in the brush used the method of studying the subjects from distance, method which was also applied in the field studies made on free specimens, using the following visual and recording equipment: a digital film camera, JVC GR-D270 Mini DV Camcoder w/25x Optical Zoom, (used cassettes: SONY dv premium, DVM60, Mini DV, 60 LP:90); a pair of binoculars 8x30M, 941263; a tripod WT 3710, attachable to the film camera. In order to recover the juvenile orphans from the crowning, I got near the stationing place using food, voice inflexions, the crouching position as to reduce the impact of re-establishing the contact, accessory objects for capturing (leafless boughs, 06.06.2007) as stimulants.
Analele Ştiinţifice ale Universităţii Al. I. Cuza Iaşi, s. Biologie animală, Tom LIV, 2008 Results and Discussion Capturing the chicks for experimental purposes was made in May, the first specimen on 15.05.2007 and the second one on 22.05.2007. As in the case of other birds, the winged C. frugilegus (L.) chicks that have more resistance and tenacity are the first to benefit from food, as they ask for it back in the nest. The ones that limit their jumps to the easy accessible props on the ground risk losing their parents support, the latter being totally preoccupied by how to defend themselves rather then by feeding the juveniles. That s why they are in danger or dying because of insufficient food. The alarm represents one of the defending methods of the C. frugilegus (L.) chick, along with excrement sprinkling (Stănescu, 1972). The maintenance of the connection with their parents differs in tonality from the sounds made by the subjects in captivity, sounds that betray the panic of isolation and that have as characteristic high, long notes, which come into harmony with the environment. No matter if the C. frugilegus (L.) juveniles are tamed or not, they utter this sort of sounds in their natural environment. When the juveniles artificially raised fly at a distance from the shelter, they also escape from the keeper s control and then they produce the visual and auditory signals for calling their parents. Together they represent an attractive signal not only for specimens of their own kind, but also for jackdaws. One can recognize their panic by observing their body language: they raise their bodies and necks and, at the same time, they press the plumage to their bodies. They beg for food in the same way both in captivity and in wilderness. It s about producing intense sounds, at the moment of food transfer, either from the parent, or from its human substitute. After a long period of starvation and contact only with its fellow birds, the presence of the human being near it stimulates the begging in a defensive form. Therefore, the wing-fluttering which accompanies the begging suffers a regression. In the absence of the contact with its wild fellow birds, the known scenery for hand-feeding in captivity allows the full reappearance of the alimentary reflex towards the keeper. In nature, the juveniles are preoccupied to preen, when they find themselves in each other s company. But, in captivity, as we noticed in the case of some starling specimens that were taken from the same nest therefore they were related one to another the interrelating is done by means of bill-tapping and not by means of preening. Until they gain alimentary independence, the juveniles beg together with the food for water as well; they don t drink alone, even if they have the opportunity. Nevertheless, if the water comes to them in a basin also appropriate for bathing, the bathing reflex is preceded by the watering. The bathing scene shows the shaking of the body, of the bill, the preening, the successive leaving and returning, and finally the abandonment of the bathing place in favour of dry and sunny resting place. From a temporal point of view, the longest period of hand-feeding interruption for the C. frugilegus (L.) subjects was about 40 hours. The reason was their orientation towards the terminal ramifications of the trees, high above the ground level, from which the hand transfer of the food could have been possible. At the end of this term, the birds reverted instantly to their way of life in captivity (06.06.2007). The exception was its playful component, which became obvious a few hours after regaining the energy consumed through starvation in the crowning of the trees used as a natural shelter. The encounter of the subjects with other rooks in the crowning offered the opportunity of filming some conflictual scenes, in which one could observe the rank superiority of the free specimens compared to the captive ones. The latter were driven away from the peripheral boughs, an aggressive behaviour towards the C. frugilegus (L.) juveniles that ask for food in freedom, incompatible with the adoption behaviour (05.06.2007).
Emanuel Târnoveanu After the feathers had grown and the bill had pigmented, we noticed the following behaviours of the captive juveniles: the use of the force of the bill on the surrounding objects grew compared to the moment that followed immediately after their capturing from nature; the aggressiveness towards the keeper s hand grew as their need for exploring began to manifest itself more and more strongly; the intensification of the panic reactions towards the free movements of the human being corroborated with their efficiency in flying; they hesitated to come near the keeper in open space, where, in spite of the need for food, the defence reaction appeared. The experiment conducted in 2005 took place on the the 18th of May, and its starting point was the finding of two chicks on the territory of a colony in the Copou Gardens in Iaşi. Subsequently to the latter s capture, the intensity of their defensive response to man was estimated, and the less shy subject was retained for taming. As a consequence of its capture for being raised in captivity, dependence on human aid settled in, manifested by positive answers regarding the seeking and maintenance of contact with the caretaker, in the latter s home as well as in the nearby natural space. The repetition in 2007 of this type of intervention, this time as multiple capture, evinced the subjects option for the occupation of the natural environment, as opposed to the expected reaction, that is the return to the caretaker (Târnoveanu, 2005). Recorded behaviours of the C. frugilegus (L.) in captivity and freedom On 17.05.2007 we noticed the following behaviours of the first juvenile that was chosen to be recovered, located on the dry bough of a hedge shrub, not far from the colony: directing itself towards the coming of the parents with food and maintaining the connection with them by means of voice, alternating with periods of rest with its head leaned on the shoulder; failed attempts to avoid a cat prepared to launch its attack, when it heard the alarm of the parents, of some help from its own species and from the C. monedula (L.) species; exhaustion caused by starvation and dehydration seen in the weak coordination of a flight attempt for saving itself from the human being s way; tail trembling subsequent to the capturing and placing itself on the verge of a twig basket which functioned as a nest ; asking for food, expressed by means of auditory signals according to the tonal register noticed at the contact with its parents, signals accompanied by wing trembling characteristic to the begging; a definite preference for moist food, in small portions; flying and feather-maintenance trainings, sleep, leaving and returning to the nest -basket; playing on the nest -basket and in its surroundings. On 18.05.2007 we noticed that the juvenile used the environment dominated by the human presence in order to beg at the first contact in the morning, followed by consuming the food given in its bill, producing at the same time pleasure sounds, playing, preening, doing flying exercises. On 21.05.2007 the C. frugilegus (L.) juvenile reacted promptly when seeing an Atio otus (L.) juvenile kept in captivity starting with 19.05.2007; the way of communication with the night-predator consisted of a series of leaning movements, combined with sounds directed towards it;
Analele Ştiinţifice ale Universităţii Al. I. Cuza Iaşi, s. Biologie animală, Tom LIV, 2008 22.05.2007, the enhancement of the exploratory and alimentary behaviour as compared to the incipient phase of the capturing; the cry which expresses the discomfort at the nest level was also heard when making the first contact with a second subject part of the experiment; 23.05.2007, 10:15, the subjects beg, a typical situation for orphan chicks and even for mammalian babies; it shows the incapacity to adjust to a closed space, typical for chicks that had the opportunity to live free in the nest until they reached an advanced age; 29.05.2007, reaction of permanently begging as the subjects were experimentally exposed in the area were they had been captured; the hand-begging behaviour, recommenced with hesitations caused by the change of scenery they knew in captivity, lacks the visual communication with the rooks outside the artificial precincts (before letting them go the partially closed balcony was replaced by a closet); 04.06.2007, 20:30, the withdrawal of the subjects for sleep to a place planted with old, high, trees, chosen in the neighbourhood of an old mulberry tree with partially ripe fruits, in order to enable them to attempt to feed on their own in the next days; 05.06.2007, the withdrawal from the way of some aggressive rooks that were passing by; long call, with the bill wide opened and with the wing feathers displayed, the shaking of the wings in front of the rooks that were passing by; moving from a tree bough to another accompanying the movement by call; alternatively beginning to explore the branches in search of dried pieces of fruit skin previously swallowed or dropped from the bill; scratching with their claws and ruffling their plumage, from the register of preening; flying exercises and sleeping in a coiled position; 06.06.2007, because of the lack of contact with the human being for a long period, the perception of the duality in the human, keeper/enemy, appeared, a fact which generated the need to preserve the freedom; under these circumstances the elder subject avoided the hand-feeding; as a consequence, we put some pieces of meat on the bough where it was located in order to feed it; 08.06.2007, 11:00, using an enamelled sheet metal basin, filled with water up to the tarsi, for drinking, bathing and playing; 12.06.2007, in case of free specimens, the begging takes visible forms, getting near the food source in this case the keeper s hand -; the playful behaviour showed regarding the newspaper in the basket and the surrounding objects, with which they train the force of the bill; rubbing their bill against the prop; looking for a certain spot in the substratum, to tap it with their bill; 13.06.2007, by introducing the subjects in the cage for feeding training, appeared the playful behaviour towards the prop, represented by a green bough; following the removal of the youngest of them from the cage, the playful behaviour grew weaker in intensity, as did the vocalizations of the remaining elder subject. Conclusions In captivity, the rook chicks that grew up together establish a weak connection with the keeper, and the single specimens develop imprinting. While the imprinted chicks
Emanuel Târnoveanu use the shelter made by the human being for them also after they regain their freedom, the half-wild chicks leave it without coming back, if they manage to break out under experimental conditions or accidentally. During the flying exercises made in the wildness, the chicks tend to follow their parents flight (Radu, 1983), as the orientation of the artificially raised chicks is done according to the keeper s presence at the shelter. The playing, the preening, the flying exercises and the preening done by the chick in its nest in the wildness appear also in captivity, excepting the latter, which was replaced by the specimens reciprocal bill-tapping. The starvation and the exhaustion of the chicks left without an alimentary support make it easier for them to accept hand-feeding, a situation in which there are also to be found the half-wild specimens recovered after escaping. The unfavourable weather conditions such as extended draught determine an increase in the number of cases of feebler chick abandonment, for which the parents couldn t fulfil their alimentary needs. The anthropic impact is reduced in the city, as long as the human being doesn t pay them any attention, but the existence of numerous predators in the urban nature (dogs/cats) is not favourable to the juveniles that fail in the first flight period. Raising juveniles in captivity can enrich the knowledge about the social behaviour of the corvids, by doing parallel studies on wild specimens. The experimental contact of the tamed subjects with their wild fellow birds in the presence of the human being must be nevertheless avoided, when this manoeuvre ends up generating panic. References Cătuneanu, I., 1953. Ciorile şi celelalte corvide şi metodele de combatere a celor dăunătoare. Editura Agro- Silvică de Stat, Bucureşti. Radu, D., 1983. Lumea neştiută a păsărilor din Delta Dunării. Editura Academiei RSR. Stănescu, D., 1972, Agresivitate şi moderare la Corvus frugilegus (L.), în timpul deranjării cuibăritului. Muzeul Brukenthal, Ştiinţe Naturale, Sibiu. Târnoveanu, E., 2005. Observaţii etologice şi ecologice la unele specii de corvide. Lucrare de licenţă, Universitatea Alexandru Ioan Cuza Iaşi.