The numbers of sparrowhawks Accipiter nisus received for study at Monks Wood Research Station increased greatly between 1963 and 1992, then declined by 50% in 1992–97. The long-term increase reflected the national population recovery over this period and followed the reduction in the use of organochlorine pesticides. It was most marked in the eastern parts of Britain where the earlier population decline was greatest. The numbers of kestrels Falco tinnunculus received for study fluctuated greatly from year to year, and showed only a slight net increase over the study period. There was a marked increase in the late 1970s in eastern districts, the only areas where kestrels had obviously declined during the peak years of organochlorine use. The sparrowhawk carcasses revealed two peaks in recorded mortality: August–September, affecting mainly recently independent juveniles; March–April, affecting similar numbers of adults and juveniles. Kestrels showed no obvious seasonal peak in recorded mortality, but fewest carcasses were received in the early breeding season April–May. Among sparrowhawk carcasses, the sex ratio was significantly biased towards females (0.8 male to 1.0 female), but among kestrel carcasses the sex ratio was close to unity. Overall, 64% of sparrowhawks and 69% of kestrels were juvenile (= first year) birds, implying a mean first-year mortality in the two species of 64% and 69%. The proportion of juveniles among sparrowhawk carcasses increased during the study period (probably reflecting improved breeding success), but the proportion of juveniles among kestrel carcasses showed no long-term trend. The most important causes of recorded deaths in both species were collisions (65% for sparrowhawk and 35% for kestrel) and starvation (18% for sparrowhawk and 40% for kestrel). The frequencies of different mortality causes recorded among carcasses found were unlikely to reflect their frequencies in the population at large, but they did reveal changes over time. During 1962–97, deaths attributed to organochlorine poisoning and shooting declined in frequency, while accidental deaths increased in frequency, especially collisions with road vehicles in kestrels and with windows in sparrowhawks.

It is now well recognized that terrestrial mammals can maintain equivalent bone stresses despite dramatic differences in body size through the adoption of extended limb positions during locomotion. However, this dynamic solution is not available to all mammals. Medium- and large-bodied arboreal mammals, such as anthropoid primates, must maintain relatively gracile and mobile limbs in order to manoeuvre in a discontinuous arboreal environment. But they must also use flexed (i.e. crouched) limb positions in order to maintain balance on arboreal substrates, thus subjecting their gracile limbs to relatively high loads. To determine how primates resolve this conflict between their kinematics and their morphology, five species of Old World monkeys were videotaped with lateral, frontal, and overhead cameras while they walked at a range of natural speeds along a runway and raised horizontal poles instrumented with a force platform. Kinematic and kinetic data on the forelimb show that during arboreal quadrupedalism, Old World monkeys do crouch when travelling on arboreal supports compared to the ground. Simultaneously, they lower vertical peak reaction forces and thereby reduce and reorient the peak resultant substrate reaction force, so that moment arms and moments are roughly equivalent on poles and the ground. This is accomplished through the adoption of a compliant walking gait characterized by high degrees of forelimb protraction, substantial elbow yield, low vertical oscillations of the body, and long contact times. The use of a compliant walking gait appears to be extremely rare among mammals and is most likely related to an initial primate adaptation to quadrupedal locomotion on terminal branches. This gait represents a previously unrecognized dynamic postural mechanism for maintenance of similar bone stresses and safety factors in both arboreal and terrestrial environments.

The effects of breeding season and reproductive status on female reproduction were investigated in the common mole-rat, Cryptomys hottentotus hottentotus, a co-operatively breeding rodent that exhibits seasonal breeding and a reproductive division of labour. Body mass, reproductive tract morphometrics, ovarian histology and plasma testosterone concentrations were studied in 80 females from 42 wild-caught colonies. Although the birth of offspring is restricted to the summer, qualitative analysis of ovarian histology revealed that females retained reproductive function during the winter non-breeding period. Seasonal differences were found in ovarian morphometrics and testosterone concentrations and are probably associated with the occurrence of pregnancy in reproductive females during the breeding period. The continuance of reproductive function during the non-breeding period in female common mole-rats parallels the situation in males, and is believed to be important in dispersal in C. h. hottentotus. The non-breeding period coincides with the period of maximal dispersal opportunities in the winter rainfall areas inhabited by the common mole-rat. Reproductive activation in dispersing animals may aid intersexual recognition, assist pair-bond formation and thereby facilitate independent reproduction. Reproductive and non-reproductive females exhibited a similar degree of reproductive function, and as for season, the only clear-cut status-related differences were associated with the occurrence of pregnancy in reproductive females. This absence of a physiologically well-defined suppression of reproduction in female common mole-rats is similar to the situation in males. Incest taboos between philopatric siblings may negate the need for a rigorous suppression of reproduction in subordinate colony members of this obligate outbreeder.

Head triangulation is a regular component of the defensive behaviour of both Heterodon and Dasypeltis. In Heterodon platyrhinos, the triangulation is achieved primarily through rotation of the quadrate in the transverse plane with the distal end of the quadrate moving dorsad. The quadrate is pulled by the m. cervicomandibularis acting in conjunction with one of the jaw adductors. Head triangulation in Dasypeltis scabra is produced by rotation of the quadrate mainly in the frontal plane with the distal end of the quadrate moving craniad. Experimental analysis documents that contraction of the m. adductor mandibulae externus superficialis is temporally linked to this displacement of the quadrate. The presence of two different mechanical bases for head triangulation in these distantly related colubrids suggests that this behavioural display has evolved independently in these ophidian lineages.

This study explores the relationship between body mass and femoral construction in armoured (dasypodids and manids) and unarmoured (caviomorph rodents) mammals. Predictive equations based on diaphyseal cross-sectional parameters provided the most accurate estimates of body mass in caviomorph rodents and dasypodids. When these equations are applied to the estimation of body mass in manids, relatively low predictive errors (<20%) are found only when caviomorph equations derived with diaphyseal cross-sectional area or moments of area are used. Dasypodid equations generally yield less accurate estimates for manids, so that armouring of the integument alone poorly discriminates femoral types. Other factors with potential to differentially impact femoral construction are also considered: although locomotor speed strongly influences mass–structure relationships within caviomorph rodents, the confounding influence of locomotor posture, fossoriality, and arboreality render these relationships less predictable across all three groups considered here. Limb structure and, hence, scaling patterns of each phylogenetic group are influenced by a unique mosaic of factors that is difficult to summarize quantitatively. The results of the study provide cautions as well as encouragements for the estimation of body mass for fossil species that have no adaptively similar living relatives.

A new species of a dendrochirotid holothuroid, Thyone herberti, is described from the deep waters of Matigulu, KwaZulu-Natal, South Africa. The new species is distinct from other species of the genus in the form of its calcareous ring, in which the radial plates are prolonged posteriorly before bifurcating, and in the presence of non-rosette-like perforated rods and plates in the tentacles and the introvert. The new species increases to eight the number of southern African species currently classified in the genus Thyone.

We summarize the information on the diet of roe deer Capreolus capreolus found in 33 European studies. After giving a short overview of the differences between the existing studies, we compare the information for each season. We submit the information, summarized in a matrix of 83 cases on 10 food groups, to a detrended correspondence analysis (DCA) and a two-way indicator species analysis (TWINSPAN). We calculate weighted averages grouping the information by season, habitat, research method and their cross-products. The weighted averages are also used as input for a multivariate ratio analysis. Since the available food items dictate the possible diet composition we further investigate the influence of the habitat on the reported food selection. The influence of season on the diet composition is compared with the effect of the habitat, and other factors such as research method and geographical location of the study site. The review shows that there is relatively little seasonal variation in the diet composition, which is more closely correlated to the habitat than to the season.

Sequences of a mtDNA gene, cytochrome b, were used to generate a phylogenetic hypothesis for the evolution of Iberian archaeobatrachian frogs of the genus Discoglossus. Results from the inferred phylogenetic branching pattern and the sequence divergence among species and populations support the following: (1) the two endemic species from Iberia, D. galganoi and D. jeanneae are sister taxa and are reciprocally monophyletic with respect to their mtDNA; (2) the geographic distribution of these two morphologically cryptic species differs considerably from previous expectations. D. galganoi is limited to the metamorphic granitic and shale substrates of western Spain and Portugal, while D. jeanneae extends over the limestone and gypsum substrates of most of eastern Spain from the Strait of Gibraltar to the Pyrenees; (3) sequence divergence between D. galganoi and D. jeanneae averages 8.6%, suggesting that the two lineages diverged before the Mio–Pliocene boundary. We suggest that these lineages were isolated by the opening of the Betic Strait and that isolation has been maintained until recently by the Guadalquivir River Basin; (4) all specimens of D. jeanneae, from the central Pyrenees in the north to the southern end of the Iberian Peninsula have nearly identical cytochrome b haplotypes, clear evidence of a rapid relatively recent (Late Pleistocene–Quaternary) expansion of the species; (5) populations of D. pictus from northeastern Spain are highly divergent from all other Discoglossus studied and do not fall within the Iberian clade.

Most New World leaf-nosed bats (Phyllostomidae) are frugivores. Many of these species are sympatric and mechanisms of resource partitioning including vertical stratification and divergent foraging strategies have been described. This study investigates a previously unexplored but potentially significant factor in resource partitioning: the relationship between feeding behaviour and fruit hardness. Data summarizing ingestive and fruit processing behaviours were collected during feeding experiments from five sympatric frugivorous phyllostomid species: Artibeus jamaicensis, Dermanura phaeotis, Sturnira lilium, Carollia perspicillata, and Glossophaga soricina. Individuals were the subjects of feeding experiments that consisted of eating hard and soft fruits of similar size, shape, and mass. Variables analysed from videotapes of the experiments describe how fruits are placed in the mouth during ingestion, the frequency of head movements during biting, the number of bites used to remove a piece of fruit, and the number of chews used to process each mouthful of fruit. Results of chi-square, log-linear, R×C, and Kruskal–Wallis tests demonstrate that feeding behaviours vary significantly with fruit hardness both within and between species. Artibeus, Dermanura, and Sturnira are behaviourally specialized for feeding on relatively hard fruits. However, Carollia, and probably Glossophaga, lack these behavioural specializations. Both mechanical and ecological implications of intra- and interspecific behavioural variation are discussed. Differences in fruit handling behaviour are also used to make explicit predictions regarding interspecific variation in masticatory morphology. This study demonstrates that the relationship between fruit hardness and feeding behaviour may be an integral part of frugivore ecology. Overall, resource partitioning among phyllostomid frugivores is a result of complex interactions among and between bats and their food plants. Controlled experimental studies such as this one provide a crucial means of dissecting these complex interactions and gaining insight into the basis of frugivore diversity.

Constraints on time and energy suggest that animals often will have to forgo one activity in favour of another. In the field, gravid garter snakes, Thamnophis elegans, eat little or nothing, especially late in pregnancy. In addition, they spend considerable time basking, presumably to aid development of their progeny. Apparently, therefore, a conflict exists between feeding and behaviours related to gestation. Alternatively, low feeding levels in the field might reflect reduced ability to catch food while gravid, or anorexia, attributable either to reduced space in the gut or to physiological suppression of appetite. In this study, by supplying abundant food in the laboratory, we test the hypothesis that gravid females are anorexic; we also examine the interactions among feeding, thermoregulation and reproductive condition. Typically, gravid females, whether fed or not, spent most of their time at the warm end of a gradient, as did fed non-gravid snakes; unfed non-gravid females spent significantly less time at the warm end. However, gravid snakes, even when presented with food ad libitum, ate less than non-gravid snakes, suggesting that they are anorexic while pregnant. Feeding and thermoregulatory behaviours of gravid females changed around the time of parturition (increased feeding, reduced warming rate). Comparable changes are seen in animals in the field, and are correlated with changes in movement pattern. Evidently, the tendency to eat little food is carried over into the laboratory, even when apparent proximate causes of the behaviour are removed. Although we cannot distinguish clearly between the two potential causes of anorexia, the evidence slightly favours physiological suppression of appetite. Physiological suppression of appetite while gravid would ensure that the urge to forage rather than thermoregulate does not diminish the chances of present reproductive success. By contrast, non-gravid snakes, faced with a shortage of food, lower their body temperature and reduce their metabolic costs.

The anatomy of the gut and the fine structure of the foregut and midgut of the nymphal, subimaginal and imaginal stages of C. dipterum are described. A new description is given of the nymphal foregut–midgut junction and its relationship to peritrophic membrane formation. Although the mouthparts are lost at the end of the nymphal stage, and the structure of the gut undergoes extensive and often degenerative changes both during and after each of the moults to subimago and imago, the structure of the subimaginal and imaginal gut nevertheless suggests that the gut is still performing some active function during both adult stages. This is also suggested by the persistence in subimagos and imagos of rhythmical waves of midgut contraction, an energetically expensive process for an animal which has ceased to feed. Although a very occasional uptake of fluids by imagos has been observed, it has been shown, by the use of a fluorescent stain, that fluid which disappears from the mouth region is most frequently being spread as a very thin film over the body surface rather than entering the gut. Frequency of midgut contraction has been measured in resting subimagos and imagos of C. dipterum and C. simile, in imagos of C. dipterum during and after being held in a dry atmosphere, in ovipositing imagos of C. dipterum, in ejaculating male imagos of C. simile and Ecdyonurus venosus, and after successive bouts of flying by E. venosus. Previous claims that the midgut contractions either control or affect oviposition and sperm ejaculation have not been substantiated. The possibility of a key relationship between the midgut contractions and the need for rapid transport of metabolities is discussed.

We measured sprint performance of phrynosomatid lizards and selected outgroups (n = 27 species). Maximal sprint running speeds were obtained with a new measurement technique, a high-speed treadmill (H.S.T.). Animals were measured at their approximate field-active body temperatures once on both of 2 consecutive days. Within species, individual variation in speed measurements was consistent between trial days and repeatabilities were similar to values reported previously for photocell-timed racetrack measurements. Multiple regression with phylogenetically independent contrasts indicates that interspecific variation in maximal speed is positively correlated with hindlimb span, but not significantly related to either body mass or body temperature. Among the three phrynosomatid subclades, sand lizards (Uma, Callisaurus, Cophosaurus, Holbrookia) have the highest sprint speeds and longest hindlimbs, horned lizards (Phrynosoma) exhibit the lowest speeds and shortest limbs, and the Sceloporus group (including Uta and Urosaurus) is intermediate in both speed and hindlimb span.

The mite Parasitellus fucorum (De Geer) (Mesostigmata: Parasitidae) lives and reproduces in the nests of bumblebees. Despite its abundance on European bumblebees and its occasional invasion of honeybee nests, little is known about its basic life-history traits and dietary requirements. This paper describes the mating behaviour, oviposition and development of P. fucorum under controlled laboratory conditions, and provides observations on the dietary preferences of its life-cycle stages.

Body size is often considered to be an important trait affecting individual fitness. In arthropods, females commonly benefit from larger size directly through increased fecundity (Roff, 1992), and males through increased mating success (Andersson, 1994). It has also been suggested that larger individuals may in general have a better survival than smaller individuals (Calder, 1983; Peters, 1983). From this suggestion it may be predicted that during stressful environmental conditions larger individuals should do better than smaller individuals.

Throughout Europe there is considerable concern about the potential impact of sawbill ducks Mergus spp. and great cormorant Phalacrocorax carbo on catches of commercial fish (reviews by Marquiss & Carss, 1994; Russell et al., 1996). A prerequisite to estimating impact is to quantify the consumption of commercially important fish by birds. This requires site-specific data on (1) bird numbers, (2) their daily food intake and (3) diet. Considerable effort has been directed at quantifying (2) and (3) and exploring the biases associated with different methods (see Carss et al., 1997 for review).

This topic formed the basis of a joint meeting with the Society for the History of Natural History on 8 December 1998.