bluuebunny/crossref_metadata_2025 huggingface dataset:
Conflicts and interactions among reproduction, thermoregulation and feeding in viviparous reptiles: are gravid snakes anorexic?
Authors: Gregory Patrick T. , Crampton Lisa H. , Skebo Kristina M.
Published: February 2006

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 structure of the foregut and midgut of nymphs, subimagos and imagos of Cloeon dipterum (Ephemeroptera) and the functions of the gut of adult mayflies
Authors: Harker Janet E.
Published: February 2006

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.
Sprint performance of phrynosomatid lizards, measured on a high‐speed treadmill, correlates with hindlimb length
Authors: Bonine Kevin E. , Garland Theodore
Published: February 2006

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.
Overwintering survival in relation to body mass in a field population of the wolf spider (Hygrolycosa rubrofasciata)
Authors: Kotiaho Janne S. , Alatalo Rauno V. , Mappes Johanna , Parri Silja
Published: February 2006

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.
Skeletons in the cupboard? Quantifying bird predation on Atlantic salmon: atlas vertebra:fish length equations revisited
Authors: Carss D. N. , Marquiss M.
Published: February 2006

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).
Attacks to humans and domestic animals by the southern cassowary (Casuarius casuarius johnsonii) in Queensland, Australia
Authors: Kofron Christopher P.
Published: February 2006

The southern cassowary Casuarius casuarius johnsonii is endemic to the tropical rainforests of north‐eastern Queensland, Australia. This species is Australia's largest bird and holds a reputation for being dangerous. Cassowaries and ostriches are the only birds world‐wide that have caused human deaths by physical attack. Incidents occur every year in Queensland, most at Mission Beach (110 km south of Cairns) and Lake Barrine (39 km south‐west of Cairns), but previously also at Mount Whitfield in Cairns. The incidence of cassowary attacks in Queensland is reviewed. Data were obtained for 221 cassowary attacks, of which 150 were against humans, 75% of these by cassowaries fed previously by people. The feeding of cassowaries appears to change their natural behaviour, making them bold and aggressive. Victims were chased or charged in 71% of the incidents, and kicked in 15%. Less frequent actions included pushing, pecking, jumping on, butting with the head and snatching food. The cassowaries appeared to be expecting or soliciting food from humans (73% of the incidents), defending food (5%), and defending themselves (15%) or their chicks or eggs (7%). Contrary to popular belief, jogging did not incite cassowaries to attack. Although cassowaries should not be considered dangerous, they can cause serious injuries. Seven attacks against humans resulted in serious injuries (puncture wounds, lacerations, broken bone) and subsequently one death, caused by cassowaries kicking or jumping on victims. In the single fatal attack, the victim was trying to kill the cassowary. Four of the seven seriously injured victims were crouching or lying on the ground.
The red fox (Vulpes vulpes) in Saudi Arabia: loose‐knit groupings in the absence of territoriality
Authors: Macdonald D. W. , Courtenay O. , Forbes S. , Mathews F.
Published: February 2006

Adaptations to extreme environmental conditions were investigated in a detailed study of red foxes Vulpes vulpes inhabiting a desert region of Saudi Arabia. Forty‐two adult foxes were live‐trapped during 3 years of field work. In contrast to red foxes studied in other areas, no strict territoriality was observed in this population. Although close interaction (separation < 1 m) was more common between members of the same, rather than different, social groups, medium distance interactions were similar. Further, intra‐group encounters were much less common than for foxes in the U.K., and foxes did not avoid each other at territory boundaries. All foxes used food‐rich sites associated with human activity, and aggregations of up to four foxes were regularly seen in these areas. It is suggested that the combination of an extremely harsh environment, with spatially and temporally variable food supplies, leads to the formation of loosely knit social groups. Saudi Arabian red foxes followed Bergmann's rule in being considerably smaller than those found in cooler areas. They also had a lighter coloured pelage than red foxes typical of Europe and North America. These morphological differences may represent adaptations to the low availability of food and rest sites in the desert.
Pupping season, perinatal sex ratio and natality rates of the Mediterranean monk seal (Monachus monachus) from the Cabo Blanco colony
Authors: Gazo Manel , Layna Jorge F. , Aparicio Fernando , Cedenilla Miguel Angel , González Luis Mariano , Aguilar Alex
Published: February 2006

Pupping seasonality, annual pup production, reproductive rate and sex ratio at birth were determined for the Mediterranean monk seal Monachus monachus colony at Cabo Blanco, the only surviving population of the species which still shows a colony structure. Data were collected by means of a monitoring programme that operated continuously in the main reproductive areas of the population during the period March 1993–May 1997. Most (84%) of the pups observed were born in two caves separated by a short distance. Although both caves were used by females to bear the pups, preferences greatly fluctuated from season to season with no apparent trend. Reproduction occurred throughout the year with a small peak of births in October. This unusual lack of seasonality is associated with the low latitudinal location of the colony and the effect of the upwelling that provides constant food throughout the year. The neonatal sex ratio did not differ significantly from 1:1 and the estimated annual productivity ranged from 44–58 pups. Taking into account population numbers, the annual birth rates were estimated to range from 0.3 to 0.43 pups per reproductive female, an extremely low rate when compared to other pinniped populations, particularly those of a similar size. Such low rates may be either an evolutionary determined characteristic of the species or a demographic consequence of the low population density over the last few centuries. Coupled with high pup mortality rates, this may account for the observed non‐recovery of the population.
Plumage polymorphism of red‐footed boobies (Sula sula) in the western Indian Ocean: an indicator of biogeographic isolation
Authors: Le Corre Matthieu
Published: February 2006

The pantropical red‐footed booby Sula sula is one of the most polymorphic seabirds. In the Indian Ocean most extant colonies hold white morph adults except on Europa Island (southern Mozambique Channel), where adults are of the white‐tailed brown morph and on Tromelin Island (western Indian Ocean), where one‐third of the birds are of the white‐tailed brown morph and two‐thirds are of the white morph. On Tromelin, the morph ratio has remained constant over the last 40 years. An extinct colony (Glorieuses Islands, northern Mozambique Channel) once supported a white‐tailed brown morph population. These results suggest that the colonies of the western Indian ocean do not constitute one great gene pool where exchanges occur, but are isolated at various degree from each other. Particularly, the population of Europa is the only current population of the Indian Ocean constituted almost entirely of white‐tailed brown morph, suggesting that it is isolated from other nearby colonies. Possible causes of isolation are discussed in the light of oceanic features of the Mozambique Channel. Although further studies are needed to understand the adaptive significance of plumage coloration in red‐footed boobies, I suggest that white‐tailed brown morph at Europa may act as a defensive camouflage against kleptoparasitism by great frigatebirds Fregata minor and brown skuas Catharacta antarctica.
Variation in daily activity of the free‐living Eurasian lynx (Lynx lynx) in Białowieża Primeval Forest, Poland
Authors: Schmidt Krzysztof
Published: February 2006

The pattern of daily activity of the Eurasian lynx Lynx lynx L. was studied by radio‐telemetry in the Białowieża Primeval Forest (eastern Poland). Radio‐tracking of 18 lynx was done by 24‐h continuous observations and by sampling on a daily basis. Lynx were active mostly at night. There was generally one peak of activity between 15:00 and 07:00 which, however, decreased slightly between 20:00 and 22:00. On average, lynx were moving for 6.5 h/day. In males, 73% of locomotory activity occurred at night, whereas females were active as long during the daylight as during the night. Movement bouts of females were shorter than those of males (1.1 h vs 2.1 h) but more frequent (4.2 vs 3.0 bouts/day). General patterns of activity of females with and without kittens were similar. However, females with kittens were active twice as long per day than non‐reproducing females. In May–August (intensive care for kittens), reproducing females were active 26% longer than in September–April. Non‐reproducing females showed the opposite pattern; they were active 60% less in May–August compared with September–April. Locomotory activity of adult males was 30–70% longer in January–March (mating season) than in other seasons. The pattern of lynx activity was shaped predominantly by searching for and consuming large prey. The lynx were active for the longest time during the days when they searched for prey but made no kill (12.5 h/day on average) and for the shortest time on the first day after killing a deer (1.6 h/day). Their moving activity increased steadily in the following days, reaching 6.8 h/day on the fourth day of consuming a killed deer. Ambient temperatures and rainfall did not significantly affect lynx activity, but there was little movement most of the time in heavy rain, and all day when the temperature was above 30 °C.
Factors influencing the selection of roost cavities by a temperate rainforest bat (Vespertilionidae: Chalinolobus tuberculatus) in New Zealand
Authors: Sedgeley Jane A. , O'Donnell Colin F. J.
Published: February 2006

The selection of roost cavities by the threatened New Zealand long‐tailed bat Chalinolobus tuberculatus was examined in unmodified temperate southern beech Nothofagus rainforest in Fiordland, New Zealand. We radio‐tracked 73 bats during spring–autumn of 1993–1997 to 155 day roosts, all of which were in trees. One hundred and forty‐nine roosts were in cavities: 84 in live trunks, 33 in dead trunks, 32 in large branches (seven in dead branches, 25 in live); and the remaining six (occupied by solitary bats) were beneath loose bark. We compared characteristics of the 84 roost cavities in live trunks with 57 random available cavities also in live trunks. Cavities used by C. tuberculatus were not a random subset of available cavities. In comparison to available cavities, bat roosts were all located in knot hole cavities, were high from the ground, and had little surrounding vegetation. All roosts were dry inside. Bats used a higher proportion of cavities which had medium sized entrances and internal cavities, and thicker cavity walls. A logistic regression model incorporating nine cavity variables classified roost and available cavities correctly 97% and 91% of the time, respectively. Distance to the nearest vegetation, cavity condition (wet or dry inside), height from the ground, and to a lesser extent internal cavity height, explained significant proportions of the variation between roost and available cavities. Bats changed roost sites virtually every day and it appeared that suitable cavities were abundant in the unlogged forests of the study area. It is unlikely that modified forests and forests managed for timber production contain such a large pool of potential roosting cavities.
Factors affecting nesting beach selection by loggerhead turtles (Caretta caretta): a multiple regression approach
Authors: Kikukawa Akira , Kamezaki Naoki , Ota Hidetoshi
Published: February 2006

Based on data obtained from 3 years' fieldwork in Okinawajima and adjacent islands of the central Ryukyus, Japan, various physical and human‐related beach characters were assessed for their relative influence on beach selection by nesting sea turtles using multiple regression analysis. Of the 23 characters considered, sand softness (measured by a specially designed tool) (positive), distance from the nearest human settlement (positive), presence of lagoon (positive), beach length (negative), and beach height (positive) were selected as influential variables in descending order. Explanations were attempted for such results in the light of correlates of these beach characters with natural and artificial factors that are believed to impact the nesting success of female sea turtles.
Skeletochronology and mark–recapture assessments of growth in the North African agamid lizard (Agama impalearis)
Authors: El Mouden El Hassan , Znari Mohammed , Brown Richard P.
Published: February 2006

Patterns of growth were studied between 1993 and 1996 in a population of Bibron's agama Agama impalearis from an arid area in the central Jbilet Mountains, western Morocco. Non‐linear regressions were used to model snout–vent lengths (SVL) and body masses of individuals caught during 1993–94 against skeletochronology age estimates. The overlap between male and female asymptotic SVLs (A) was negligible demonstrating sexual dimorphism, although there was no evidence of differences in characteristic growth rates (k) between sexes (males: A= 119.43 ± 2.29 mm and k= 0.849 ± 0.09 [month−1], females: A= 108.59 ± 3.19 mm and k= 1.079 ± 0.162 [month−1]). Asymptotic body mass differed substantially between sexes (males: 71.2 ± 3.1 g, females: 45.8 ± 4.2 g), but corresponding characteristic growth rates were similar (0.753 ± 0.339 and 0.789 ± 0.623 [month−1], respectively). The mark–recapture method provided generally higher and more reliable asymptotic size estimates (using the logistic‐by‐length non‐linear regression model) than the skeletochronology‐based estimates. Growth parameters were also estimated on an individual year basis. Only male characteristic growth rate showed a significant year‐to‐year variation (0.010 ± 0.006 to 0.024 ± 0.007 [day−1]), although this may have been due to a lack of statistical power. Annual variation in the absolute growth rate was detected only in hatchlings (0.087 ± 0.018 to 0.273 ± 0.132 mm.day−1) and adult males (0.089 ± 0.030 to 0.206 ± 0.100 mm.day−1).
Intraguild predation may explain an amphipod replacement: evidence from laboratory populations
Authors: Dick Jaimie T. A. , Montgomery W. Ian , Elwood Robert W.
Published: February 2006

In a laboratory experiment that permitted both observations of the behaviour of individuals and the monitoring of small populations, the role of ‘intraguild predation’ in the elimination of the freshwater amphipod Gammarus duebeni celticus by the introduced G. pulex was examined. Over 18 weeks, deaths in single and mixed species replicates were monitored. Rates of ‘mortality’ (deaths not due to cannibalism or predation) did not differ between the species. Gammarus d. celticus, however, was more cannibalistic than G. pulex and, in both species, males were more often cannibalized than females. In mixed species replicates, the mean proportions of animals preyed upon did not differ among replicates with differing starting proportions of the two species, nor was there a difference between the sexes in numbers preyed upon. G. pulex, however, preyed more frequently on G. d. celticus than vice versa, and this became more pronounced over time. In 87% of mixed species replicates, G. pulex eliminated G. d. celticus. The results support the proposition that intraguild predation may be the primary mechanism whereby G. pulex rapidly replaces G. d. celticus in freshwater. Integrating behavioural observations with population level monitoring may thus link pattern and process in behaviour and ecology.
House mice and wood mice in and around an agricultural building
Authors: Tattersall F. H.
Published: February 2006

Wood miceApodemus sylvaticusand house miceMus domesticusare two of the commonest and most intensively studied British mammals. However, relative to the vast literature on non‐commensal and laboratory house mice (Berry, 1981, 1991), and woodland wood mice (Flowerdew, Gurnell & Gipps, 1985; Flowerdew, 1991) little is known of the ecology of either species in and around farm buildings. Farm buildings and their surroundings are particularly important for house mice, which are a major stored‐product pest (Meehan, 1984). In Britain they live largely indoors but also make limited use of hedges and fields in the summer (Rowe & Swinney, 1977; Montgomery & Dowie, 1993). Wood mice are very abundant on agricultural land, and occasionally use buildings (Green, 1979; Montgomery & Dowie, 1993; Tew & Macdonald, 1993).
Does the method of set‐aside establishment affect its use by wood mice?
Authors: Tattersall F. H. , Fagiano A. L. , Bembridge J. D. , Edwards P. , Macdonald D. W. , Hart B. J.
Published: February 2006

The set‐aside scheme, whereby land is removed from arable production, is primarily aimed at manipulating agricultural surplus within the European Community, but has potentially great consequences for biodiversity and wildlife management (Feber et al., 1995; Macdonald et al., 1998; Sotherton 1998). Managed inappropriately, set‐aside could prove environmentally damaging by reducing biodiversity and directly harming certain species, such as ground‐nesting birds (Thompson, 1993). Conversely, appropriately managed set‐aside could foster desirable ecological communities, with enhanced populations and biodiversity.
The social calls of Kuhl's pipistrelles Pipistrellus kuhlii (Kuhl, 1819): structure and variation (Chiroptera: Vespertilionidae)
Authors: Russo Danilo , Jones Gareth
Published: February 2006

The aim of this study was to describe the structure of social calls produced by Kuhl's pipistrelles Pipistrellus kuhlii. Bats foraging around street lamps in the Campania region, Southern Italy, were recorded. Calls were produced by bats during chases and, similarly to those of Pipistrellus pipistrellus, were probably used to repel conspecifics from hunting sites. Calls often had three components, lasted on average 34 ms and contained most energy at about 17 kHz. A positive correlation was found between the frequencies of maximum amplitude of echolocation and social calls. Social calls from two adjacent populations differed in their peak frequencies, and possible hypotheses for this variation are given. The structure of P. kuhlii social calls was compared with those of the 45 and 55 kHz P. pipistrellus phonic types. Kuhl's pipistrelle calls lasted longer and showed lower values of minimum and peak frequencies. These differences can help to discriminate between field recordings of P. kuhlii and P. pipistrellus where the two species occur sympatrically.
Paracrobeles psammophilus sp. nov. (Nematoda: Cephalobidae) from El Saler, Valencia (Spain)
Authors: Navarro Pilar , Lluch Javier
Published: February 2006

Paracrobeles psammophilus sp. nov. (Nematoda: Cephalobidae) is described from soil of the Dehesa de El Saler (province of Valencia, Spain). This is the second record of a species of the genus Paracrobeles Heyns, 1968. The new species is characterized by rounded cheilorhabdions and the large spicules and gubernaculum of males.
A case of co‐operative nursing and offspring care by mother and daughter feral horses
Authors: Cameron Elissa Z. , Linklater Wayne L. , Stafford Kevin J. , Minot Edward O.
Published: February 2006

Among mammals, non‐offspring nursing is the most extreme form of communal parenting. This is because lactation is the most energetically costly part of parental investment (Clutton‐Brock, 1991; Packer, Lewis & Pusey, 1992). Non‐offspring nursing is most common in species characterized by large litters and small kin groups (Packer et al., 1992; e.g. lions Panthera leo: Pusey & Packer, 1994). Although non‐offspring nursing has also been reported in monotocous species (e.g. water buffalo Bubalus bubalus, Murphey et al., 1995; African elephant Loxodonta africana: Dublin, 1983; Lee, 1987; Indian elephant Elaphus maximus: MacKay, 1973; Rapaport & Haight, 1987; fallow deer Cervus dama: San José & Braza, 1993) it is almost always associated with reproductive errors (Riedman, 1982) such as milk theft or exclusive adoption (Packer et al., 1992). However, simultaneous non‐offspring nursing in monotocous species has been reported in some bat species (e.g. McCracken, 1984; Eales, Bullock & Slater, 1988), African elephants (Lee, 1987), and captive Indian elephants (Rapaport & Haight, 1987). Recent research, however, suggests that nutritive non‐offspring nursing in African elephants is rarer than previously thought as most reported instances were probably non‐lactating juveniles allowing infants to suckle (Lee & Moss, 1986; Lee, 1987, 1989).
Morphology of spermathecae in the estuarine crab Chasmagnathus granulata Dana 1851 (Grapsidae, Sesarminae)
Authors: López Greco L. S. , López G. C. , Rodríguez E. M.
Published: February 2006

The morphology of the spermathecae (seminal receptacles) was studied in the grapsid crab Chasmagnathus granulata, both from the macroscopic and the microscopic points of view. Female adult crabs were collected throughout the year. Once in the laboratory, the right spermatheca was fixed in Bouin solution; histological sections were stained with haematoxilin–eosin. The observations indicated that the spermathecae belonged to the ‘ventral type’ described by Diesel (1991), related to the ‘hard female’ mating system of C. granulata described previously. They presented two distinct zones: the inner one (white‐coloured), where the double layer oviduct opened ventrally; and the outer one, of translucent, ‘jelly‐like’ appearance, where the communication with the genital duct could be observed. The spermatozoa were only observed in the ‘jelly‐like’ zone, but not as discrete packets, suggesting that spermatozoa from different matings could mix in the spermathecae of C. granulata. The spermathecae also showed seasonal variation, with the lowest degree of development observed during autumn. Post‐moulted females always showed collapsed spermathecae.
Expansion of a grey seal (Halichoerus grypus) breeding colony: changes in pupping site use at the Isle of May, Scotland
Authors: Pomeroy P. P. , Twiss S. D. , Duck C. D.
Published: February 2006

Until the mid 1970s only a few grey seal Halichoerus grypus pups were born each year on the Isle of May, Scotland, but 1408 pups were born there in 1994. We examined changes in overall site use, individual pupping site fidelity and success in relation to local population density and topography. The area of the island used by seals for breeding has increased as the population increased. Between 1988 and 1994 an index of the proportion of the island's northern area occupied by seals increased from 0.48 to 0.65, while the average population density in these occupied areas decreased over the same period. Although seals have begun to breed in southern parts of the island that were unused previously, other apparently suitable breeding areas on the island remain vacant. Fine scale digital elevation models were constructed using a GIS to evaluate the topographic characteristics of occupied areas and assign topographic ‘costs’ to areas used by seals for breeding on the Isle of May. Seals were associated generally with areas close to the numerous access points from the sea. New areas occupied in the later years of the study had a higher topographical ‘cost’ than the traditional sites. Thus, in an expanding colony such as the Isle of May, areas colonized early in the colony's history were those close to access points and/or standing water and at low elevations. Subsequent expansion resulted in an increase in the areas occupied by seals, but these newly colonized areas were less suitable, and their occupiers were subject to increased topographic ‘costs’. Pup mortality rates were similar in areas of high and low breeding density. Aggressive behaviour between breeding females is the likely mechanism which acts to limit local animal density. Mothers marked at the Isle of May since 1987 returned there to breed with few exceptions, and most females that returned were faithful to their previous pupping sites (median distance between sites used in consecutive breeding seasons = 25 m). Site fidelity persisted even when a previous pupping was unsuccessful and most individuals' pupping locations did not change gradually with time. Comparison with other colonies suggests that the spatial scale of site fidelity is related to the scale of topographic variation within the breeding site.
Role of the statolith in functioning of the acceleration receptor system in squids and sepioids
Authors: Arkhipkin Alexander I. , Bizikov Vyacheslav A.
Published: February 2006

Morphology of statoliths and anatomy of statocysts were studied in five species of Gonatidae, Moroteuthis robusta (Onychoteuthidae) and Galiteuthis phyllura (Cranchiidae) from the northern Bering Sea, and Todarodes pacificus (Ommastrephidae) from the Pacific waters near Japan. A special experiment was carried out in order to observe statolith mobility on the macula statica and possible endolymph flows within the statocyst in freshly caught gonatid squid Berryteuthis magister. It was found that the statolith may deviate at small acute angles around three axes running through its centre of rotation (located near the spur) without any visual damage of its attachment area to the macula. This finding enabled us to re‐consider previous theories and to create a new model of the squid statocyst functioning with the statolith as detector of multidimensional movement. Two types of statolith morphology are distinguished: demersal type statoliths characteristic of near‐bottom decapods, and pelagic type statoliths characteristic of all pelagic squids and not dependent on their systematic position. Phylogenetic and ecological features of the statocyst and statolith structure are established. Possible evolutionary trends in development of different types of statocysts in decapods are discussed.
Tropical tree diversity, forest structure and the demography of a frugivorous rodent, the spiny rat (Proechimys semispinosus)
Authors: Adler Gregory H.
Published: February 2006

Populations of the Central American spiny rat Proechimys semispinosus isolated on eight small islands in Panama were sampled monthly for 1 year to examine the relationships of demography to tree species composition and forest structure. Demography was characterized by calculating seven variables from the monthly census data. Tree species composition was determined by marking, measuring and identifying all trees ð 10 cm in diameter at breast height (dbh) on each island. Forest structure (tree stature, density and species richness) was quantified by measuring seven variables at each of the 470 sampling stations. Bivariate correlations were computed between spiny rat demography and tree species composition and forest structure. To examine whether islands with more similar tree species composition or forest structure supported P. semispinosus populations with more similar demography, dendrograms based on complete‐linkage cluster analysis were constructed. Spiny rat densities were correlated positively with the density of large‐fruited fig trees and non‐linearly to an index of forest age based on tree species composition. Spiny rat densities were not related to any structural variable. Dendrograms based on cluster analysis showed that spiny rat demography did not map onto forest structure, overall tree species composition or any group of selected tree species except figs Ficus spp. Thus, islands with more similar fig tree composition contained spiny rat populations with more similar demography. Tree species composition, which partly determines resource abundance, is apparently more important than forest structure in influencing spiny rat demography. Proechimys semispinosus has a temporally and spatially variable demography, and this flexible demography, in concert with an ability to use diverse resources, presumably promotes abundance and persistence in heterogeneous tropical forests and may contribute to the ubiquity of this rodent.
Ovarian structure and oogenetic cycle in the millipedeCatamicrophyllum caifanum(Diplopoda: Iulidae)
Authors: Warburg M. R. , Gealekman Olga
Published: February 2006

The ovaries and oocytes of a iulid millipedeCatamicrophyllum caifanumVerhoeff 1920, were studied in an oak woodland and a planted pine forest in the Mediterranean region in northern Israel. The changes in the stages and number of oocytes are described throughout the activity period of this millipede: October–February. Four stages of female germ cell development could be distinguished: (1) the early stages of oogenesis when the female germ cells (= oogonia) are still embedded in the germ layers of the ovarian epithelium; (2) two sizes of previtellogenic oocytes entering the ovarian lumen are distinguishable. Small ones (< 0.1 mm) observable only in microscopic sections, and larger ones (0.2–0.45 mm) that could be seen under the dissecting microscope. The small previtellogenic oocytes were present in the ovary throughout the study period. The oocytes apparently undergo vitellogenesis during autumn; (3) with the accumulation of yolk, a third stage consisting of small, medium and large vitellogenic oocytes can be discerned; (4) the mature, post‐vitellogenic oocytes, elliptic in shape and yellowish in colour, appear towards the end of autumn. In winter only post‐vitellogenic oocytes are found, disappearing from the ovary towards the end of winter. The number of mature, post‐vitellogenic oocytes is positively correlated with the female's body size.Catamicrophyllum caifanumhas therefore an annual oogenetic cycle breeding once yearly during winter. This, together with the fact that its ovary contains oocytes belonging to different stages (= generations), indicates that it can breed at least four and possibly up to seven times during its lifetime.
Mouse (Mus musculus) stocks derived from tropical islands: new models for genetic analysis of life‐history traits
Authors: Miller Richard A. , Dysko Robert , Chrisp Clarence , Seguin Renee , Linsalata Luann , Buehner Gretchen , Harper James M. , Austad Steven
Published: February 2006

Founder effects, together with access to unoccupied ecological niches, may allow rodent populations on isolated islands to evolve constellations of life‐history traits that distinguish them from their mainland relatives, for example in body size, litter size, and longevity. In particular, low intrinsic mortality risks on islands with reduced predator numbers and not subject to harsh winter climates may in principle support the development of stocks with extended longevity. Conversely, the conditions under which laboratory rodents are typically bred are thought to select for genotypes that produce large, rapidly maturing races with high early reproductive rates but diminished longevity. To test these ideas, and to generate new mouse stocks suitable for genetic and molecular analysis of the processes that time life‐history events, we have developed specific pathogen‐free stocks from mice trapped from three distinct populations: the U.S. mainland (Idaho) and the tropical Pacific islands Majuro and Pohnpei. Mice from all three locations were found to be shorter and lighter, to have smaller litters, and to have higher faecal corticosterone levels than mice of a genetically heterogeneous stock derived from four common laboratory inbred strains. Among the wild‐derived stocks, mice from Pohnpei and Majuro were significantly lighter and shorter than Idaho‐derived animals, even in populations kept from birth under identical housing conditions. Litter size and reproductive success rates did not differ significantly among the three wild‐derived stocks. Although further work will be needed to see if, as predicted, the wild‐derived stocks differ from one another and from laboratory mice in longevity, these stocks provide useful tools for genetic dissection of factors that regulate body size and reproductive success.
Clustering of colonies in an expanding population of New Zealand fur seals (Arctocephalus forsteri)
Authors: Bradshaw Corey J. A. , Lalas Chris , Thompson Caryn M.
Published: February 2006

New Zealand fur seals in the New Zealand area are increasing in number following earlier depletion by Polynesians and Europeans. Otago Peninsula, South Island is a region where recent re‐colonization has occurred. We identified 27 breeding and 41 non‐breeding colonies in 1998. At higher densities the shortage of space in breeding colonies may initiate emigration by first‐time breeders to suitable sites nearby. This hypothesis assumes philopatry (repeated return to a natal site) and site fidelity (repeated return to a non‐natal site). We quantified the rate of increase in pup production at Otago Peninsula since the early 1980s using annual counts of fur seals ashore from 1994 to 1998 and data on pup numbers before 1994 from the literature. The exponential rate of increase (b) ranged from 0.22 to 0.30 (95% confidence interval) and the average (arithmetic) rate of annual increase (r) was 0.30. To search for evidence of philopatry, site fidelity and immigration, relationships between counts of pups established colonies in 1996–1998 were measured and found to be highly correlated. We then tested whether new breeding colonies were established nearer to existing breeding colonies than would be expected by chance. There was significant spatial clustering of new breeding colonies around the 6 focal (established) colonies. We found no evidence for an association between the appearance of new colonies and r at nearby established colonies. Increasing numbers of fur seals on Otago Peninsula have resulted in the rapid proliferation of colonies, and their clustering is indicative of a ‘spill‐over’ effect where young individuals choose to breed near to established breeders.
Helpers provide no detectable benefits in the European badger (Meles meles)
Authors: Woodroffe Rosie , Macdonald David W.
Published: February 2006

Many studies of co‐operatively breeding vertebrates have shown that social groups which contain more helpers experience higher reproductive success. Few of these studies, however, have demonstrated that this is a causal relationship. Using data on a co‐operatively breeding population of European badgers Meles meles, this study shows that the relationship between helper number and group reproductive success is a spurious one generated through the effect of territory quality. Within this population, most variation in cub production, growth rate and survival is explained by variation in food availability between years and between territories. Unusually for mammals, juvenile mortality is markedly higher in females than in males. After controlling for such effects, helpers appear to have only negative effects upon group reproductive success, and mothers with helpers are in poorer condition at the end of the breeding period than those without helpers. A high proportion of helpers are sexually mature females which have failed to breed as a result of intense competition for resources. Under such circumstances, alloparental care represents a low‐cost, low‐benefit behaviour which may mitigate the negative impact that non‐breeding group members have upon the reproductive success of their close relatives.
Developmental pattern and larval stages of Polystoma indicum Diengdoh & Tandon, 1991 (Monogenea: Polystomatidae) in rhacophorid anurans
Authors: Dutta Mamoni , Tandon Veena
Published: February 2006

The developmental pattern of Polystoma indicum Diengdoh & Tandon, 1991 occurring in the urinary bladder of the frogs Rhacophorus nigropalmatus, R. reinwardtii and Polypedates leucomystax from Meghalaya (north‐east India) was studied. Non‐ciliated larval stages were recovered in the gyrodactyloid‐I and post‐gyrodactyloid‐I stage mostly from the branchial chambers of the tadpoles; only rarely were they found in the intestines. These stages possessed features of bladder‐destined forms and showed a gradual acquisition of 2, 4 and then 6 opisthaptoral suckers, coupled with an increase in the size of the body and various structures. While a conspicuous increase was noticeable in the dimensions of the hamuli, the size of the microhooks remained almost the same from the 2‐suckered larval stage to the adult. The larval migration to the final destination seems to follow an external route leading to the cloaca of the metamorphosing host. The prevalence data of both the larvae and the adult flukes indicate a preference towards R. nigropalmatus amongst the three rhacophorid host species. The gyrodactyloid‐II, i.e. neotenic larvae were not encountered at all either on the external gills of the very young tadpoles or even in the branchial chambers of the older ones.
Extreme body size variability in the golden silk spider (Nephila edulis) does not extend to genitalia
Authors: Uhl Gabriele , Vollrath Fritz
Published: February 2006

Nephila edulis is a spider with large body size variability in males and females. Genital characters show negative allometric values compared to somatic characters. In males, the embolus (the most important structure for sperm transfer) had a significantly lower coefficient of variation than body size. This suggests that male genitalia are under stabilizing selection favouring intermediate size. Female N. edulis showed a trend similar to males regarding allometric values in genitalia. In females, however, the variation coefficient in a specific genital character crucial for successful copulation did not differ from that of indicators for overall body size. This suggests that in Nephila the genitalia of the females experience less stabilizing selection than those of the males. In male and female genitalia, the mode of selection seems to cause developmental instability not in degrees of fluctuating asymmetry but in the degree of data scatter which indicates a lower coefficient of determination.
Movements and group structure of giraffe (Giraffa camelopardalis) in Lake Manyara National Park, Tanzania
Authors: van der Jeugd Henk P. , Prins Herbert H. T.
Published: February 2006

Movements and group structure of giraffe Giraffa camelopardalis were studied in Lake Manyara National Park, northern Tanzania. The giraffe population in Manyara had increased from 60 to 85 individuals between the early 1980s and 1991. This increase may have been the result of an increase in browse availability as a result of a dramatic decline in elephant numbers, and bush encroachment following a series of anthrax epidemics that killed impala. Giraffe densities in Manyara are high compared to other areas within the Masai ecosystem, and Manyara probably serves as a dry season refuge. Females were found in small, yet unstable groups, while males associated randomly with each other. Neither males nor females were confined to single localities, although home ranges were small compared with studies in areas with low giraffe densities. In one area within the park a more stable group was found, and resident males who were probably defending a temporary harem, engaged in necking contests with immigrant males. A comparison with other studies showed that giraffe density, home‐range size, mobility and group stability differ across different habitats. The tendency that more stable groups are found in high density areas might be taken as evidence for the occurrence of resource defence polygyny in such areas.
A comparative study of morphometry in shell‐bearing molluscs
Authors: Tokeshi M. , Ota N. , Kawai T.
Published: February 2006

A comparative study was conducted on the ontogenetic variation in morphometry of a total of 29 shell‐bearing molluscan species occurring on an intertidal stony shore in south‐western Japan. The relationships between shell size and total weight and between shell size and flesh weight were all highly significant on logarithmic scales with the slopes having values of about three. The arcsine‐transformed proportion of shell weight out of total weight varied among and within different morphological/taxonomic groups, ranging from 58.6% in Acanthochiton defilippi to 76.4% in Nerita albicilla. The allometry of shell weight was analysed by regressing the arcsine transformed values of the proportion of shell weight against total weight in each species. The slope (β) of the regression varied substantially among different taxa, with all three possible cases, i.e. β > 0, β≊ 0 and β < 0, being observed. Thus, depending on molluscan species, the proportion of shell mass either (1) increases, (2) does not change, or (3) decreases with increasing body mass. Variation in the value of β was to some extent explained by the proportion of shell mass of young individuals of each species; species with relatively high proportions of shell mass in small individuals tended to have low β. Interspecifically, it was shown that shell mass scaled in proportion to body mass for this assemblage of 29 species. Consideration was given to the theoretical background of variation in shell morphometry, with particular reference to the shell as a defence structure.
Spalacopus cyanus (Rodentia: Octodontidae): an extremist in tunnel constructing and food storing among subterranean mammals
Authors: Begall Sabine , Gallardo Milton H.
Published: February 2006

Burrow systems of two coastal populations (El Alamo and Los Maitenes) of the social octodontid rodent Spalacopus cyanus were studied in central Chile. Tunnel systems were estimated to be up to 600 m long, ran at a depth of 15 cm and had a diameter of 6 cm. Tunnel openings were usually unplugged, and a minor preference toward southern and south‐eastern direction of entrances was apparent. Nests, frequently found in the root system of Berberis actinacantha at a depth of 30 cm, consisted of grasses, roots and plastic bags. Nests serve for sleep, care of the pups and as latrines. Many staphylinid beetles of the genus Edrabius and other invertebrates were found in the breeding nests. Food chambers contained up to 13.2 kg of bulbs of the geophyte Dioscorea longipes collected by a single colony consisting of 26 animals (including 10 adults) and were frequently found at El Alamo. However, no bulbs were found at Los Maitenes, where the coruros forage above ground on leaves of Convolvulus arvensis within a radius of about 10 cm of the entrances. Apparently, the burrow design is also affected by food availability, soil quality, and colony size.