Condenser ECM-672) and digital recorder (DAT Casio DA-2). The vocalizations are acquired with a Macintosh IIci equipped with Audiomedia software ...
Ethology Ecology Q Evolzttion 6 : 385-452. 1994
XV CONVEGNO DELLA SOCIETA ITALIANA D1 ETOLOGIA
FIFTEENTH MEETING O F T H E ITALIAN SOCIETY FOR THE STUDY O F ANIMAL BEHAVIOUR (Castiglione dell3 Pescaia, Italy, September 22-24, 1992)
Invited Lecture and Communications
Pubblicazione finanziata con i contributi ~~~~'UNIVE DEGLI R S ISTUDI T A DI PISA e ~ ~ ~ ~ ' A M M I N I S T ~ W PROVINCIALE ZIONE D I GROSSETO
Fifteenth Meet. Ital. Soc. Anim. Behav.
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A longitudinal behavioural study of wild mice colonies in artificial territories
P. PALANZA, D.MAINARDI and S. PARMIGIANI Dipartirneizro di Biologia e Fisiologia Generali, Universita di Parliza, Viale delle Scienze, 43100 Pannu, Ilalj> It is now generally accepted that male and female aggressiveness can shape the social structure of animal populations. The house mouse provides, perhaps, the best understood current model for studying this phenomenon. In order to investigate male and female competitive strategies, outside or during breeding, and their roles in shaping social structure, a longitudinal behavioural study of established pairs in artificial territories (consisting of multiple cages connected by runways) was carried out. Intruder tests were performed at different stages of the reproductive cycle. All mice used originally derived from a population of wild mice trapped around Capalbio (central Italy), and had been bred in our laboratory for about five generations. Male residents were highly aggressive and always intolerant toward male intruders, but not toward female intruders. -Conversely, resident females attacked preferentially same sex intruders after colony establishment and during pregnancy, but attacked intruders of both sexes when nursing young. Tolerance of females decreased in the reproductive stages. Male and female residents appear to be respectively responsible for the intolerance versus same sex intruders. When two females were present in a colony, only one reproduced successfull~l.This suggests that, as is true for males, females of this stock compete among themselves f o r the opportunity to reproduce; they can be exclusively territorial or form a dominance hierarchy which probably determines reproductive success. Males compete among each other for establishing and holding a territory (andlor social rank), and ultimately to mate with females. Since reproduction is largely confined to domiterritorial males, intermale aggression mav limit reproductive potential of nant or exclusivel~~ same sex conspecifics and serve the function of species dispersion and colonisation. Females become aggressive only when they become associated with a male holding a territory; this suggests that interfemale competition is strictly related to reproductive activity. The presence of a territorial male seems to be a kev-factor in controlling social organization, since impregnation o r appropriate stimuli coming from a male holding an area are necessal-y to induce female intrasexual aggression. However, females seem to be largely responsible for the regulation of the reproductive potential of a deme unit through intrasexua1 aggression (intolerance towards other females), inhibition of subordinate reproduction and the killing of unrelated young. In view of the fact that infanticide is a competitive strategy in this species, the spatial and temporal stability of demes seems to be a crucial factor in determining the reproductive success of both male and female residents.
Reproductive biology in Malagoniella puncticollis (Blanchard) (Coleoptera Scarabaeidae Canthonina): first evidence
C. PALESTRINI l , E. BARBERO l , M. ZUNINO * and M. LUZZATTO
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Dipartilne~ziodi Biologia Aninzale, Universita di Toritzo, Via Accaden~iaAlbertina 17, 10123 Tori120, Ital!. * Istituto di Zoologia, U~ziversitadi Pale~wzo,Via Archirafi 18, 90123 Palenno, Iial!. ;vi~lugoniellapuncticollis is a coprophagous, telephagic and telecoprid species, distributed in N-W Argentina, S Bolivia, Paraguay, Uruguay and S-W Brasil.
438
Communications
During a field study carried out in February 1989 in a xeric area of Argentina (Cafayate dune, Salta), a paedotrophic nest of M. puncticollis, containing a pair and two brood-balls, each one with a third instar larva, was obsenred. Such observation allowed us to suppose that, not only paedotrophic nesting behaviour, but truly parental care occurs in this species. More than 100 individuals were collected at the "Reserva Natural de Nacurian" (Mendoza, Argentina) in December 1990, and reared in the laboratory under controlled conditions. On the basis of our observations, carried out during one and a half years, it is possible to point out the following: ( i ) the female builds a pear-like brood-ball - very rarely two [size varies from 1.8 X 2.0 to 3.5 X 4.2 cm; ?( = 2.5 X 3.0 cm ( n = 83)] within a hypogean chamber, just larger than the brood-ball itself; (ii) the pre-imaginal instars show the following mean development times: egg 4.4 days (n = 12), 1-11 instars 5.3 davs ( n = 101, 111 instar 19.3 days (n = 27), pupa 16.7 days (n = 21); (iii) in about 213 of considered cases the female has been Found in the paedotrophic nest containing egg or larva, even in the advanced development phase; (iv) at least adults have a stridulation mechanism (elytro-alar); (v) adults accomplish repeated nesting cycles and seem to be very long-lived. Present evidence does not demonstrate indisputably our hypothesis, nevertheless it accords with the main features of the reproductive bioiogy of thc genus Klzeper (Scarabaeina). The latter is, with the exception of scattered, non-coprophagous, species, the only ball-roller group where prolonged parental care is known.
Comparative analysis of the vocalizations of the Hooded Crow Cowus corone cornix and the Carrion Crow Cowus corone corone
C. PALESTRINI, A. ROLANDO, S. LONGATO a n d M. ZUCCHELLI Dipartimento di Biologia Animale, Universita di Torino, Via Accademia Albertina 17, 10123 Torino, Italy A series of studies conducted in the Alpine hybridization zone of northwestern Italy has highlighted the partial reproductive isolation among the Hooded Crow and Carrion Crow. In fact a reduced Fitness of the hybrids (SAINO1990) was found, as well as a certain propensity 1992). for assortative mating (SAINO1990, ROLANDO The t w o forms, besides their colouring, seem quite different morphometrically (SAINO in press) and the proven dominance of the Carrion Crow over the Hooded Crow (SAINO& SCATIZZI 1991, ROLANDO & GIACHELLO 1992) could very well depend on the slight size imbalance. Assortative mating is probably facilitated by the complex of morphological differences between the two subspecies. However the hypothesis that the discrimination might be based on non-morphological characters should not be excluded. The purpose of the present study is, in fact, to analyze comparatively the vocalizations of the Hooded Crow and Carrion Crow in areas of sympatry in order to ascertain whether there is some differentiation at this level as well. The recordings were made in the wild, along the Dora Baltea River branch, in Valle d'Aosta and in the Alto Canavese. In this initial phase of the research, we collected mostly protest vocalizations obtained by disturbing the female at nest. The recording was obtained with the use of a directional microphone (Sony Electret Condenser ECM-672) and digital recorder (DAT Casio DA-2). The vocalizations are acquired with a Macintosh IIci equipped with Audiomedia software (Digidesign). The digital signals are then converted at a workstation in a LabVIEW 2.0 environment (National Instrument) which analyzes the amplitude of the temporal signal (oscillogram) and that of the various frequency components in their temporal evolution (sonogram).
