The use of sewage treatment works as foraging sites by insectivorous bats

Sewage treatment works with percolating filter beds are known to provide profitable foraging areas for insectivorous birds due to their association with high macroinvertebrate densities. Fly larvae developing on filter beds at sewage treatment works may similarly provide a valuable resource for foraging bats. Over the last two decades, however, there has been a decline in filter beds towards a system of “activated sludge”. Insects and bat activity were surveyed at 30 sites in Scotland employing these two different types of sewage treatment in order to assess the possible implications of these changes for foraging bats. Bat activity (number of passes) recorded from broad-band bat detectors was quantified at three points within each site. The biomass of aerial insects, sampled over the same period as the detector surveys, was measured using a suction trap. The biomass of insects and activity of Pipistrellus spp. was significantly higher at filter beds than at activated sludge sites. In addition, whilst foraging activity of Pipistrellus spp. at filter beds was comparable to that of adjacent “good” foraging habitat, foraging at activated sludge sites was considerably lower. This study indicates the high potential value of an anthropogenic process to foraging bats, particularly in a landscape where their insect prey has undergone a marked decline, and suggests that the current preference for activated sludge systems is likely to reduce the value of treatment works as foraging sites for bats

Biogéographie de Madagascar = Biogeography of Madagascar

Les #Tenrecidae$ de Madagascar comprennent au moins 26 espèces toutes endémiques. Ces espèces sont dérivées d'une race colonisatrice, arrivée du continent africain il y a une soixantaine de millions d'années. Aujourd'hui, les descendants de cette race occupent une large gamme de niches écologiques, grâce à une radiation in-situ extensive. Cet article rend compte des données récentes acquises sur la différentiation énergétique et reproductive qui s'est produite dans cette famille de mammifères, et des facteurs impliqués dans ces procesus évolutifs. Le taux métabolique en repos (TMR) est corrélé au poids corporel et aux facteurs écologiques. Les espèces de petits tenrecs qui vivent dans les forêts centrales et orientales montrent des valeurs de TMR similaires à ceux des musaraignes tropicales. Au contraire, les espèces vivant dans les forêts sèches et dans les zones arides montrent des valeurs de TMR plus faibles que celles attendues ; ces espèces montrent une torpeur quotidienne ou saisonnière. Les valeurs de température du corps (TC) des tenrecs dans la phase non-reproductive sont significativement inférieures à celles de toutes les autres espèces d'insectivores, à part la taupe dorée. Néanmoins, chez toutes les espèces de tenrecs, les valeurs de TMR et TC sont plus élevées pendant les phase de grossesse et de lactation ; ceci est peut-être lié à une amélioration d'homothermie. La variation intraspécifique de la durée de gestation est peut-être liée à la torpeur quotidienne de la grossesse, phénomène considéré jusqu'à maintenant comme spécifiquement limité aux microchiroptères hétérothermiques. Les adaptations qui augmentent la production reproductive sous les contraintes d'une faible TC et d'une durée de gestation uniforme et longue, sont discutées. (Résumé d'auteur

Changes in pituitary, ovarian, and testicular activity in harbour seals (Phoca vitulina) in relation to season and sexual maturity

This study examined pituitary sensitivity to exogenous gonadotrophin-releasing hormone (GnRH) in relation to time of year and changes in plasma progesterone, testosterone, luteinising hormone (LH), and follicle-stimulating hormone (FSH) concentrations during the annual cycle of adult and juvenile harbour seals (Phoca vitulina vitulina). There was no significant difference in seasonal changes in reproductive hormone levels between six captive individuals and seals caught from the wild (n = 80). Based on results from both the captive and the wild individuals, the plasma progesterone concentration was elevated in late gestation, whereas it declined at the equivalent time in nonpregnant females. The progesterone concentration was also elevated during the phase of delayed implantation, but there was no difference between pregnant and nonpregnant seals. In captive seals given exogenous GnRH, the LH concentration peaked 10-20 min after injection of GnRH, and the magnitude of the LH response depended upon the dose up to ~120 ng·kg-1. FSH did not respond to GnRH in the time course of the experiment. Pituitary sensitivity to GnRH was greatest in the summer and autumn and lowest in the winter and spring. Seasonal changes in pituitary sensitivity were apparent in both adults and juveniles. There was evidence that three of the four juvenile seals attained puberty during the study. We conclude that the seasonal patterns of pituitary sensitivity and plasma hormone concentration in harbour seals are consistent with a reproductive cycle under photoperiodic control and with the general mechanisms underlying photoperiodic control of seasonal reproduction in higher vertebrates