bluuebunny/crossref_metadata_2025 huggingface dataset:
Activity patterns, diet, and feeding efficiency of Harlequin Ducks breeding in northern Labrador
Authors: Rodway Michael S
Published: April 2011

The lack of data on summer diet and feeding behaviour for the endangered eastern North American population of Harlequin Ducks (Histrionicus histrionicus) prompted a study of activity patterns and feeding ecology in a coastal stream in Hebron Fiord, Labrador. Diurnal activity patterns varied by habitat and changed through the season. Extensive feeding occurred in slow-moving waters, contrary to expectation. Females spent 40% of daylight hours feeding during the prelaying period, more than twice the time spent by males and higher than that reported in other studies. Diurnal feeding patterns showed little variation in the prelaying period and major peaks of activity in the morning and evening during incubation and brood rearing. Larval Simuliidae (Diptera) were absent from a fecal sample taken in July but dominated the prey remains in feces collected in August. Dive times averaged 10-24 s and varied with depth of water. Dive-pause ratios of 1.7-2.2 were lower than previously reported. The results support the hypothesis that populations are food-limited on the breeding grounds, and suggest that there may be greater energy constraints on foraging effort in river specialists than in dabbling or other diving waterfowl.
Effects of endophyte consumption on food intake, growth, and reproduction in prairie voles
Authors: Durham William F , Tannenbaum Michael G
Published: April 2011

Grasses infected with fungal endophytes are known to deter herbivores. Athough ingestion of infected plant tissues has detrimental effects on insects, birds, domestic livestock, and laboratory rodents, little is known about the consequences of endophyte consumption for wild rodent consumers. This multigenerational study investigated how consumption of tall fescue (Festuca arundinacea) seeds infected with the endophytic fungus Acremonium coenophialum affects prairie voles (Microtus ochrogaster). Breeding pairs were fed one of three base diets: laboratory rodent chow (C; control diet), 50% uninfected tall fescue seeds plus 50% chow (E-), or 50% endophyte-infected seeds plus 50% chow (E+). In the first generation, the E+ diet suppressed food and water intake, growth rates, and reproductive success, so no voles fed on the E+ diet could be followed in the second generation. In general, voles of the two generations performed similarly on the C and E- diets. Our findings show that prairie voles are sensitive to the presence of endophytes, or associated alkaloids, in their diets, and suggest that free-ranging voles avoid consuming endophyte-infected plant tissues if other foods are available.
Avian recolonization of eastern Canadian bogs after peat mining
Authors: Desrochers André , Rochefort Line , Savard Jean-Pierre L
Published: April 2011

To evaluate the potential of bog ecosystems to recover following peat mining, we compared bird species richness,abundance, and assemblages and vegetation among naturally revegetated and undisturbed bog sites in southeastern Quebec.Based on mining history, we selected 28 sites (12 natural, 9 abandoned after blockcut extraction, and 7 abandoned after vacuumextraction) in 15 bogs. We estimated percent cover for six vegetation strata in 106 plots with 100 m radius, on which bird pointcounts were conducted in 1993 and 1996. Vegetation structure differed significantly between natural, post-blockcut andpost-vacuum sites. While vegetation cover was almost complete in natural sites, abandoned sites, especially post vacuum, wereless vegetated, even after 20 years. Bird species richness and abundance were similar in natural and post-blockcut sites andboth were higher than in post-vacuum sites. Ten of the 28 species studied in detail responded to site perturbation. Among them,the Palm Warbler was most closely associated with natural sites. Bird communities were closely associated with vegetationstructure. Communities of post-blockcut sites were more similar to those of natural bogs than were bird communities ofpost-vacuum sites. Since the blockcut method of peat mining is no longer economically feasible, we conclude that bog habitatrestoration should be accompanied by a preservation safety net area to counteract the lasting effect of vacuum peat mining onbird species assemblages.
Seasonal patterns in food intake, live mass, and body composition of mature female fallow deer ( Dama dama)
Authors: Weber M L , Thompson J M
Published: April 2011

Seasonal oscillations in food intake, live mass, and body component masses were investigated in two groups, each of 4 mature fallow does, which were fed high and low energy density diets ad libitum over a 17-month period. The aim of the experiment was to quantify seasonal patterns of food intake, live mass, and body tissue masses and to assess the effect of high- and low-energy diets on these patterns. Total body fat, muscle, and viscera masses were estimated on 10 occasions using computer-aided tomography. When food intake was expressed in megajoules of metabolisable energy per day, there was little difference between the groups fed the high- and low-energy diets. Food intake showed a clear deviation from a regular annual oscillation during the summer, when intake by both groups was reduced. Seasonal oscillations were apparent in live mass, empty body mass, muscle mass, and total body fat mass, with maximum values in autumn and minimum values in spring. Viscera mass did not show a seasonal pattern but was closely related to food intake. There was a lag phase of 6-7 weeks in the correlation between food intake and live mass and body tissue masses, suggesting that the changes in food intake were a precursor of subsequent changes in live mass and body composition. Further oscillations in muscle and fat masses persisted independently of changes in empty body mass, which indicated a differential change in these components according to season.
Molecular systematics, morphological analysis, and hybrid crossing identify a third taxon, Aedes (Halaedes) wardangensis sp.nov., of the Aedes (Halaedes) australis species-group (Diptera: Culicidae)
Authors: Brust Reinhart A , Ballard J William O. , Driver Felice , Hartley Diana M , Galway Nora J , Curran John
Published: April 2011

Phylogenetic and morphological analyses, male morphology, and hybrid crossing indicate that a population from Wardang Island, South Australia, is distinct from the monophyletic series of populations of Aedes (Halaedes) australis (Erichson) 1842 from Victoria, Tasmania, New South Wales, and New Zealand. The name Aedes (Halaedes) wardangensis has been assigned to the new species. Phylogenetic analysis of DNA sequences from the cytochrome oxidase II and internal transcribed spacer loci support the resurrection of Aedes (Halaedes) ashworthi Edwards, 1921 (Brust and Mahon, 1997). Aedes ashworthi is known only from Western Australia and was found to be infertile when crossed with Ae. wardangensis from South Australia and Ae. australis from New Zealand. The hybrid of Ae. australis from New South Wales × Ae. australis from New Zealand was fertile for three generations, documenting these as conspecific.
Stenurus minor (Metastrongyloidea: Pseudaliidae) infections of the cranial sinuses of the harbour porpoise, Phocoena phocoena
Authors: Faulkner Jacqueline , Measures Lena N , Whoriskey Fred G
Published: April 2011

Seventy-eight harbour porpoises, Phocoena phocoena (33 females, 45 males), were obtained in summer (June-September) as incidental by-catch from the cod fishery in the Gulf of St. Lawrence and examined for the presence of cranial sinus nematodes. Stenurus minor (Kühn, 1829) Baylis and Daubney, 1925 were present in the cranial sinuses of all adult porpoises (>1 year old, N = 66, mean intensity = 2362, range = 87-8920) and absent in all young of the year (<1 year old, N = 12). Only fifth-stage worms were observed and these were equally distributed between the right and left sides of the skull (mean intensity = 1158 and 1213 in the left and right side, respectively). However, S. minor were approximately twice as numerous in the frontal sinuses as in the ear sinuses. Mean intensities of S. minor were similar among all infected porpoises. Parasite load had no apparent effect on porpoise body condition (measured as percent blubber mass of the carcass). No gross lesions associated with the presence of numerous S. minor in the cranial sinuses were observed. There was an inverse relationship between the intensity of S. minor infection and mean worm length, which is suggestive of a "crowding effect." Mean worm length was 17.8 ± 0.2 mm in lightly infected porpoises and 16.1 ± 0.2 mm in heavily infected animals.
Energetic implications of disturbance caused by petroleum exploration to woodland caribou
Authors: Bradshaw Corey JA , Boutin Stan , Hebert Daryll M
Published: April 2011

Woodland caribou (Rangifer tarandus caribou) in Alberta are classified as endangered and apparently have declined. Disturbance from petroleum exploration has been implicated as a possible cause, so we constructed a simple model to estimate the energy costs of multiple encounters with disturbance (i.e., loud noise). Our objective was to estimate if woodland caribou in northeastern Alberta have been exposed to enough disturbance from 1988 to 1993 to cause winter mass loss to exceed either (i) 15% autumn mass or (ii) 20% autumn mass. A single disturbance event costs caribou 3.46-5.81 MJ. Caribou would have to encounter (i) 20-34 (mean = 27) disturbance events to lose >15% mass over winter and (ii) 41-137 (mean = 89) events to lose >20% mass. There were five occasions from 1988 to 1993 (i.e., in a particular caribou distribution zone and winter) when the encounter rate (number of potential encounters per square kilometre) exceeded a level expected to result in caribou losing more than the estimated mean 15% autumn mass. There were four occasions when the encounter rate exceeded the lower limit expected to cause >20% mass loss and one occasion when it approached the mean rate expected to cause >20% mass loss. Modelling the cumulative influence of disturbances demonstrates an effect on individual energy loss during winter at certain exploration intensities. It is the first attempt at estimating the consequences of petroleum exploration for wildlife in northeastern Alberta and provides important information for future research and land-use management.
Morphological and ecological adaptations in montacutid bivalves endo- and ecto-symbiotic with holothurians
Authors: Kato Makoto
Published: April 2011

Morphological and ecological characteristics of two montacutid bivalve species endo- and ecto-symbiotic with holothurians were studied in the Ryukyu Islands, Japan. The endosymbiotic species Entovalva lessonothuriae sp.nov. was found inside the oesophagus of the holothurian Holothuria (Lessonothuria) pardalis. The bivalve had an internal shell wrapped by a mantle and a well-developed bilaterally flattened foot, with a byssal gland on the right-hand side that attached to the wall of the oesophagus. The foot, usually bent to the left, enabled the bivalve to dodge through the sand flow in the host's oesophagus. The presence of well-developed gills suggests that the bivalve is still a filter-feeder. The bivalves were generally found in pairs, i.e., a larger female, sometimes brooding veliger larvae, and a smaller male. The ectosymbiotic species Anisodevonia (gen.nov., separated from Devonia) ohshimai was attached to the skin of a synaptid holothurian, Patinapta ooplax. The bivalve could creep actively on the host using its foot, which was bent to the right. The left- and right-handedness of the foot flexion corresponded to an endo- and an ecto-symbiotic life-style, respectively. It is suggested that the endosymbiotic species evolved from an ectosymbiotic ancestor without the loss of locomotory, respiratory, and feeding functions.
Sperm whale social units: variation and change
Authors: Christal Jenny , Whitehead Hal , Lettevall Erland
Published: April 2011

Sperm whale (Physeter macrocephalus) photoidentification data spanning 12 years of study around the Galápagos Islands were examined to investigate the size, variability, and stability of social units. Adult females and immature whales of both sexes have two types of associates: "constant companions," which are members of an individual's "stable" social unit, and "casual acquaintances," which are temporarily associating members of different units. We analysed long-term association patterns and calculated that individuals have a mean of 11.3 constant companions. Estimated social unit size ranged from 3 to 24 individuals. Evidence of splitting and merging of units and of transfer of individuals between units is presented. The estimated overall frequency of these unit-membership changes is 6.3% per individual per year. These forms of unit dynamics are rare in species with male dispersal and matrilineally related social groups, and cannot be easily explained in this species. There is considerable variation in unit size (perhaps caused by demographic processes), suggesting that the benefits of remaining in a social unit usually outweigh selection for some optimal unit size. However, the occurrence of merging and transfers suggests that the ecological or social cost/benefit of leaving one's matrilineal unit may sometimes outweigh the cost/benefit of staying.
Caractéristiques des sites de mise bas de l'orignal (Alces alces)
Authors: Chekchak Tarik , Courtois Réhaume , Ouellet Jean-Pierre , Breton Laurier , St-Onge Sylvain
Published: April 2011

The movements of female moose, 14 in 1995 and 20 in 1996, were recorded by radio-tracking to examine the characteristics of calving sites in the centre of Quebec. Females were spotted by helicopter every 3 or 4 days mean = 3,5 ± 0,4; n = 15) between mid-May and early June (1995: May 17 - June 9; 1996: May 21 - June 6) so that the exact dates and sites of calving could be determined. Topography and vegetation at the sites were determined using topographic maps and terrestrial surveys and were compared with control sites chosen randomly within the home range of each female. Twenty-six calving sites were identified, 10 in 1995 and 16 in 1996. Calving sites were situated seven times more often at the top of hills (69%; n = 26) than control sites (10%). They were also situated more often (88%) on hills with less than 10% slopes than control sites (52%). Finally, distance to the nearest river was greater for calving sites mean = 543 m) than for control sites mean = 339 m). Canopy and food, altitude, distance to a road or a water source, drainage, and orientation did not differ between calving sites and control sites. Although this is not a formal test, the observed characteristics of calving sites support the hypothesis that calving females choose sites where the risks of fawn predation are lowest. As females do not repeatedly use the same calving sites and as the physical characteristics of the sites and nature of the forest at the sites are not limiting, we do not see any reason why moose calving sites should be submitted to particular protection or management measures.
Symmetrical vascularization patterns in normal and retinoic acid treated limb regenerates of the axolotl, Ambystoma mexicanum
Authors: Scadding Steven R , Burns Andrew
Published: April 2011

The purpose of this investigation was to determine whether there were any asymmetries in the vascularization of the limb-regeneration blastema in the axolotl, Ambystoma mexicanum, that might be related to pattern formation, and to determine if retinoic acid could modify the vascular patterns of the blastema. We used acrylic casts of the vascular system of the limbs to assess the pattern of vascularization. We observed a very regular symmetrical arrangement of capillaries in the limb-regeneration blastema that did not appear to be modified by doses of retinoic acid sufficient to modify the limb pattern.
Effect of soil conditions and body size on digging by prediapause Colorado potato beetles (Coleoptera: Chrysomelidae)
Authors: Noronha Christine , Cloutier Conrad
Published: April 2011

The effect of soil temperature, density, and moisture on digging of prediapause Colorado potato beetles (Leptinotarsa decemlineata (Say)) was studied in 1.9 cm diameter soil columns. Beetles dug for between several days and a few weeks before finally resting. Speed of digging peaked during the initial hours and decreased slowly thereafter. A soil temperature near 16°C was the optimum in terms of incidence of digging (95%) and final diapausing depth. The intensity of these two responses was reduced at higher (<= 24°C) and lower (>= 8°C) temperatures. When given a choice of four soil densities, 50% of the beetles preferred the lightest soil (0.64 g/cm3), but 11% chose the heaviest soil (1.14 g/cm3). When a range of nine soil densities was provided in a no-choice situation, digging speed and depth decreased exponentially with increasing soil density, suggesting that energy invested in digging is limited. Peak digging speed during the first 2 h averaged 4.33 cm/h in light soil and only 0.83 mm/h in heavily compacted soil. Dry soil (40-45% water by mass) inhibited digging, while nearly saturated soil (65%) was fully acceptable. Digging speed and depth were maximal in the 50-55% moisture range. Beetle size had a positive effect on digging. For each additional 1 mg of fresh mass, beetles dug for 1 day longer, reached 1 cm deeper in soil columns, and dug 0.5 mm/h faster during the initial burst of digging.
The effect of hibernation status and cold-acclimation on hepatocyte gluconeogenesis in the golden-mantled ground squirrel (Spermophilus lateralis)
Authors: Staples James F , Hochachka Peter W
Published: April 2011

Rates of gluconeogenesis were measured in hepatocytes isolated from torpid, aroused, summer-sampled non-cold-acclimated, and summer-sampled cold-acclimated Spermophilus lateralis. At 7°C, no net glucose synthesis is measurable. At 37°C, 10 mM alanine supports low rates of gluconeogenesis that do not differ among groups. With 10 mM lactate/1 mM pyruvate, rates of gluconeogenesis are 60% higher in the torpid group than in the summer non-cold-acclimated group. With 10 mM glycerol, rates of gluconeogenesis are 2-fold higher in the torpid, aroused, and summer cold-acclimated groups than in the summer non-cold-acclimated group. The higher rates of gluconeogenesis with lactate/pyruvate and glycerol are probably more related to cold-acclimation than to hibernation/seasonal status per se, as no differences were noted among the cold-exposed groups. The observed differences in rates of gluconeogenesis cannot be readily explained by differences in apparent oxidative efficiencies of gluconeogenesis or activities of key gluconeogenic enzymes, but may be related to a general upregulation of hepatocyte metabolism accompanying cold-acclimation. This is reflected in the higher rates of hepatocyte oxygen consumption in the cold-exposed groups. Increased biosynthetic capacities during the winter season may not be a specific adaptation to hibernation, but may still contribute to energy savings over the hibernation season by helping to minimize euthermic arousal intervals.
Increase in oxidative capacity of pigeon pectoralis muscle before and after fledging
Authors: Rathgeber Errin E , Rosser Benjamin WC
Published: April 2011

Using the pectoralis muscle of the pigeon (Columba livia), we previously showed that at fledging, both fast-twitch oxidative-glycolytic (FOG) and fast-twitch glycolytic (FG) fiber types retain a myosin isoform characteristic of the neonatal period, despite the birds being at adult body mass. Our aim here was to test the hypothesis that muscle fibers of the pigeon pectoralis increase their aerobic capacity both before and after fledging. Pigeons aged from 1 week after hatching through to adulthood were used. Adopting a microdensitometric technique from studies on mammalian muscle, the activity of succinate dehydrogenase (SDH) within individual fibers was quantified as optical density and used as an index of aerobic capacity. We demonstrate a strong linear correlation (r2 = 0.936) between optical density of FOG fibers and time exposed to the SDH incubation medium. Optical density of FG fibers, however, could not be discerned from background staining. SDH activity in FOG fibers increased logarithmically (r2 = 0.969) with the age of the birds, increasing 2.5-fold from 1 week through to adult. Thus, aerobic capacity did increase both before and after fledging. In addition, within FOG fibers, aerobic capacity and myosin content appear to have different timetables of development.
Phylogenetic relationships of three genera of Erpobdellidae (Hirudinoidea), with a description of a new genus, Motobdella, and species, Motobdella sedonensis
Authors: Govedich Fredric R , Blinn Dean W , Keim Paul , Davies Ronald W
Published: April 2011

A new genus, Motobdella, is recognized for Erpobdella montezuma Davies, Singhal, and Blinn, 1985. In addition, a new species for this genus, Motobdella sedonensis, is described. Morphological characters that include the presence of crop caeca, number and size of the eyes, arrangement of the eyes, arrangement of ovisacs, position of the gonopore, structure and size of the sensilla, coloration, and position of the anus distinguish this new genus from Erpobdella and Nephelopsis. DNA fingerprinting methods were used to examine the phylogenetic relationships of these genera and corroborated the morphological data supporting the evolution of this genus with two distinct species.
Timing and synchrony of activity in caribou
Authors: Maier Julie AK , White Robert G
Published: April 2011

Activity data were analyzed to assess activity patterns of caribou (Rangifer tarandus granti). We hypothesized that equal day and night activity, termed nychthemeral activity, would be expected if food constitutes a limiting resource for a highly gregarious species. To test this hypothesis, we investigated activity patterns of two caribou populations at the same latitude: one captive with no food limitation and the other wild and free-ranging in the Alaska Range in interior Alaska known to be at the end of a 3-year low plane of nutrition. For captive caribou, activity patterns were determined from focal-animal behavioural observations each month except May. Data were collected on wild caribou using activity-recording radio collars in each of three seasons: late winter, postcalving, and midsummer. Wild and captive caribou exhibited nychthemeral activity and did not time activity to sunrise or sunset. Wild caribou exhibited no among-group synchrony. Within-group synchrony was high in both herds. Wild caribou exhibited significantly fewer cycles of activity than captive caribou. Longer resting bouts in late winter, and longer active bouts postcalving and in midsummer for wild caribou, were interpreted as behavioural responses to ecological effects of limited food availability, with and without snow, and disturbance by insects.
Limb development in the Pacific giant salamanders, Dicamptodon (Amphibia, Caudata, Dicamptodontidae)
Authors: Wake David B , Shubin Neil
Published: April 2011

The larvae of Pacific giant salamanders, Dicamptodon (Dicamptodontidae), develop in streams, display precocious limb development, and possess a full complement of digits at hatching. Limb morphogenesis was studied using cleared whole mounts stained with Alcian Blue or by immunohistochemical methods to reveal stages of limb development. Limb morphogenesis in these salamanders conforms to the general caudate pattern, i.e., preaxial dominance and precocious development of an initially isolated digital arch, despite some differences in detail from other salamander taxa. These comparisons support the hypothesis that a fundamental ground plan characterizes limb development in salamanders which transcends adaptive modifications related to ecology and life-history evolution. This ground plan differs from that which characterizes frogs and amniotes, which shows postaxial dominance and a digital arch that arises from basal elements.
Effects of edges and habitats on small mammals in a prairie ecosystem
Authors: Pasitschniak-Arts Maria , Messier François
Published: April 2011

To investigate the abundance and distribution of small mammals relative to edge in a fragmented prairie landscape, small mammals were trapped in south-central Saskatchewan from 1991 to 1993 in four different habitat types: idle pasture, delayed hay, dense nesting cover, and rights-of-way. In total, 995 small mammals, representing nine species, were captured on 14 182 trap-nights. No edge effect was recorded in idle pasture or dense nesting cover; however, an edge effect was observed in delayed hay fields. Edge effect across all habitats was dependent on season: relative abundance of small mammals was significantly higher along edges in spring but not in summer. Of the two most common species captured, Peromyscus maniculatus showed no affinity for edges, while Microtus pennsylvanicus was significantly more abundant along edges than in the habitat interior. Relative abundance of small mammals was highest in dense nesting cover, intermediate in delayed hay and along rights-of-way, and lowest in idle pasture. Relative abundance was also lower in spring than in summer. Species richness was higher along edges than in the habitat interior and was also greater in summer than in spring. Species diversity showed no edge or season effect.
Upper pH tolerance limit of the zebra mussel (Dreissena polymorpha)
Authors: Bowman Michelle F , Bailey R C
Published: April 2011

The upper pH tolerance limit of the zebra mussel (Dreissena polymorpha) has not been established experimentally. This study was designed to test the effect of elevated pH on the health and survivorship of zebra mussels. Dishes that contained 250 mL of pond water were assigned to four replicates of control, zebra mussel control, low-NaOH, medium-NaOH, and high-NaOH treatments. Except for the control replicates, two zebra mussels were added to each dish. Every other day, volumes of 1 M NaOH were added to low- (50 µL), medium- (100 µL), and high-NaOH (200 µL) treatments. All zebra mussels but one in the high-NaOH treatment died between days 17 and 31 at pH 9.3-9.5. On the last day of the study, day 31, three zebra mussels in the medium-NaOH treatment died at pH 9.5-9.6. The zebra mussels in the high-NaOH treatment moved and formed byssus attachments less often and had lower mean dry body mass than zebra mussels in other treatments. Dishes that contained zebra mussels had more algal genera than control dishes. In this experiment, the upper pH tolerance limit of zebra mussels was between 9.3 and 9.6 and may have been dependent on the rate of pH change.
The effect of Kudoa paniformis infection on the reproductive effort of female Pacific hake
Authors: Adlerstein S A , Dorn M W
Published: April 2011

The effect of the myxosporidean Kudoa paniformis on the annual reproductive effort of the coastal stock of Pacific hake (Merluccius productus), on which it is a common parasite, is investigated. Female Pacific hake collected off the central Oregon coast in December 1988 were analyzed for prevalence and intensity of parasites. Reproductive effort was estimated by the number of yolked oocytes present in the ovaries immediately prior to spawning (potential annual fecundity), using the volumetric method. The effect of the parasite was evaluated through an analysis of covariance where fecundity was modeled as a function of fish length and parasite prevalence. An additional analysis of covariance evaluated the effect of the intensity of parasite infection on fecundity. Results show that the fecundity of Pacific hake is significantly reduced in the presence of K. paniformis infections and that the detrimental effect escalates with the intensity of infection. The potential effects on the population dynamics of the Pacific hake coastal stock are discussed.
Effects of food abundance and environmental parameters on foraging behavior of gadwalls and American coots in winter
Authors: McKnight S Keith
Published: April 2011

Diurnal behaviors of wintering gadwalls (Anas strepera) and American coots (Fulica americana) were studied at Guntersville Reservoir, Alabama. Feeding accounted for a substantial amount of time spent by gadwalls (>50%) and coots (>62%). Feeding rate (pecks per minute) of female gadwalls was higher than that of males, and foraging speed (metres per minute) of unpaired gadwalls was higher than that of paired birds. For both gadwalls and coots, foraging speed increased and feeding rate decreased over time. Stepwise multiple regression was used to test the effects of food abundance, day length, ambient temperature, and mean daily wind speed on feeding rate and foraging speed. Foraging speed increased with declining food abundance for both gadwalls and coots. Additionally, day length accounted for a small but significant amount of variation in foraging speed of coots. Moving faster while feeding probably allowed gadwalls and coots to maintain adequate intake of nutritious food items from a declining food resource. Variation in feeding rate of gadwalls was not explained by food abundance or environmental variables. Feeding rate of coots decreased with declining food abundance and increased with decreasing ambient temperature. As food abundance declined, reduced density of suitable food items resulted in fewer surface pecks and more time-consuming dives. The higher feeding rate of coots at lower ambient temperatures probably resulted from increased thermoregulatory costs. Unlike coots, gadwalls typically do not dive, and adjusted to reduced food abundance at the surface by stealing food from diving coots. Because gadwalls exploited coots bringing food items to the surface in January and February, gadwall feeding rate during this time was somewhat uncoupled from variation in food abundance at the surface. Although diurnal foraging time is limiting for some waterfowl species, results from the present study indicate that variation in foraging behaviors of gadwalls and coots wintering in Alabama predominantly was a response to changes in food abundance.
Cryptic radiation in erpobdellid leeches in xeric landscapes: a molecular analysis of population differentiation
Authors: Govedich Fredric R , Blinn Dean W , Hevly Richard H , Keim Paul S
Published: April 2011

Despite apparent long-term geographic isolation, many invertebrates demonstrate little apparent morphological differentiation. To examine underlying genetic differentiation, eight erpobdellid leech populations from widely dispersed northern Arizona aquatic ecosystems were examined by means of amplified fragment length polymorphism genetic markers. These populations were primarily Erpobdella punctata, though two populations, Motobdella montezuma and Motobdella sedonensis, have been described as novel taxa. Data from 137 polymorphic loci were used to estimate genetic heterogeneity (θ), migration rates (Nm), and genetic similarities (Dice's method) among these populations. Analysis of molecular variance and cluster analysis (unweighted pair-group method) were used to show population structure and to partition the genetic variance. Our analysis indicates that northern Arizona leech populations are genetically isolated (θ = 0.72, Nm = 0.09), with significant (p < 0.01) differentiation among populations. In addition, no relationship was found between genetic and geographic distances (r = 0.19, p = 0.22), which is consistent with long-term isolation even when populations are in close proximity. The large amount of genetic differentiation reveals levels of diversity and complexity not apparent from morphological comparisons alone and suggests that erpobdellid leeches in the arid landscape of the southwestern U.S.A. are in fact evolving independently from one another.
Reproductive success is a misleading indicator of nest-site preferences in the Red-winged Blackbird
Authors: Pribil Stanislav
Published: April 2011

Several methods are used to detect nest-site preferences of birds. One method postulates that individuals will prefer those nest-site features that increase their reproductive success. To determine which features affect reproductive success, and hence should be preferred, the method examines correlations between reproductive success and various nest-site features. When a statistically significant correlation is found, it is concluded that individuals exhibit a preference for that feature. In the absence of a correlation, it is concluded that individuals are indifferent to the feature. Here, I argue that this method may lead to misleading conclusions. If good sites are abundant, all individuals should choose them. Consequently, there will be little variation in the features of the chosen sites. This limited variation, when related to reproductive success, may fail to yield a statistically significant correlation and thus lead to the erroneous conclusion that individuals have no preference. An alternative method of detecting nest-site preferences is to compare features of chosen sites with features of available sites. In this study, I used both methods to investigate nest-site selection in the Red-winged Blackbird (Agelaius phoeniceus). I compared vegetation features of nest sites with those of randomly selected sampling sites and found significant differences. The differences imply that Red-winged Blackbirds prefer vegetation that grows in small patches and is tall and sparse, and the plants have thick stems. I found no relationship between these vegetation features and reproductive success. These results suggest that Red-winged Blackbirds have strong preferences for certain vegetation features, but these preferences cannot be detected from correlations with reproductive success.
Are there thermoregulatory constraints on the timing of pupping for harbour seals?
Authors: Hind A T , Gurney WSC
Published: April 2011

In this paper we describe a detailed model of the thermal balance of a seal in air. We tested the model against the limited experimental information available on thermoregulation for harbour seals (Phoca vitulina) in air. Since a mother must meet both her own and her pups' energetic costs, we suggest that there may be an energetic advantage for harbour seals in Scotland if lactation is timed to coincide with the most favourable conditions for hauling out. To test this hypothesis, we used the harbour seals in the Moray Firth as our case study. The model does predict an energetic cost resulting from thermoregulation during haul-out for a mother and her pup in the Moray Firth. Taking the mother and pup as a unit, we estimate the minimum cost during lactation. This combined cost, which must be met by the female seal, is similar to the minimum metabolic rate during haul-out for the summer predicted from the model. In winter the predicted minimum metabolic rate exceeds the lactation cost, and an additional cost of thermoregulation results. The model predicts the most energetically favourable time for lactation to be June and July, and this is coincident with the timing of pupping in this seal population. We suggest that for harbour seals in Scotland, the timing of pupping may be influenced by the thermoregulation costs of haul-out. This provides indirect evidence that thermoregulation influences haul-out behaviour in this small phocid species.
Effects of exposures to siblings or sibling odors on sibling recognition in prairie voles (Microtus ochrogaster)
Authors: Paz y Miño C. Guillermo , Tang-Martínez Zuleyma
Published: April 2011

Determining the mechanisms of sibling recognition is important for understanding social behavior and the basic parameters of population dynamics (cycles) in microtine rodents. Previous studies have shown that, after relatively short periods of isolation, prairie voles (Microtus ochrogaster) no longer recognize their siblings. In this study we tested the hypothesis that brief encounters of prairie voles with siblings or sibling odors during a period of isolation can maintain social memory and the ability of animals to recognize their siblings over time. Six-week-old voles of both sexes that were isolated for 21 days and exposed (on days 3, 6, 9, 12, 15, and 18 of this 21-day isolation period) to brief encounters (30 min for each encounter) with their siblings continued to recognize their siblings when tested for social interactions at 42 days of age. Only females exposed to odors of same-sex siblings during the period of isolation continued to recognize their sisters. Males exposed to odors of same-sex siblings did not recognize their brothers when tested for social interactions at 42 days of age. These results demonstrate that after dispersal prairie voles need occasional encounters with their siblings, or their siblings' odors (at least in females), to reinforce social memory and the ability to recognize kin over prolonged periods of time. This study is the first to provide empirical evidence that helps us understand the mechanism by which sibling prairie voles, which are philopatric or often settle in home ranges close to one another, almost never form breeding pairs.
Testing the intergenerational conflict hypothesis: factors affecting adoptions in Audouin's gulls, Larus audouinii
Authors: Oro Daniel , Genovart Meritxell
Published: April 2011

We studied chick adoption in Audouin's gull, Larus audouinii, a ground-nesting seabird, to test several predictions made by the intergenerational-conflict hypothesis (ICH). The effects of food availability on adoptions were considered by comparing two breeding seasons with differing food supply. As predicted, adoptions were significantly more frequent when food was in shorter supply (48% of broods affected) than when it was more available (18.5%). Adoptions occurred during the first week of the chick-rearing stage; after that, aggression by adults towards intruding chicks increased significantly, which suggests that mechanisms of parent-offspring recognition were established. Foster parents incurred certain costs, since their offspring had lower chances of survival than those in control broods. However, contrary to the ICH hypothesis, adoptees did not select foster broods in relation to the age of the resident chicks. Survival of wandering chicks was no higher than that of chicks who stayed in their natal brood. Results suggest that chicks move only as a response to neighboring chicks being fed by an adult, and in Audouin's gulls, adoptions might be considered reproductive errors.
Historical biogeography of Jamaica: evidence from cave invertebrates
Authors: Peck Stewart B
Published: April 2011

The Jamaican fauna of obligately subterranean invertebrates contains 25 species of terrestrial troglobitic onychophorans, arachnids, isopods, and hexapods and 16 species of freshwater - brackish water stygobites, mostly crustaceans. Cladistic analyses of the faunas are not available. In place of this, general track analysis of the cave-restricted terrestrial faunas suggests closest relationships with Jamaican forest faunas, followed by other West Indian forest or cave faunas, and lastly Central American forest faunas. Over-water dispersal best accounts for the presence of the terrestrial epigean ancestors of the fauna in Jamaica, and they must have arrived after Jamaica became emergent in the early Miocene (about 20 Ma). The terrestrial cave fauna then descended from the epigean ancestors. In contrast, the aquatic fauna invaded from the sea, but also after the Miocene emergence. There is no evidence for a macro-vicariance origin of the cave-evolved fauna from one existing in cave environments at the time when Jamaica separated from proto-Middle America. The troglobites probably arose on Jamaica through habitat shift or Pleistocene climatic change (both micro-vicariance mechanisms). Seven terrestrial and three aquatic species seem to be phylogenetic relicts. These relicts also have a stronger relationship to other Antillean islands than to Central America. This fauna shows no evidence of a South American origin. There is a very significant species-area linear regression for Greater Antillean stygobites but not for troglobites (probably because Hispaniola is not sufficiently studied).
Reproductive products in the adult snow crab (Chionoecetes opilio). I. Observations on spermiogenesis and spermatophore formation in the vas deferens
Authors: Sainte-Marie Guy , Sainte-Marie Bernard
Published: April 2011

Some of the events unfolding in the vas deferens of the adult snow crab (Chionoecetes opilio) were examined by means of light microscopy. Sperm cells entered the vas deferens as precursors of immature spermatids and developed into immature or mature spermatids within it. However, spermatozoa were not observed in the male reproductive tract. Two types of amorphous matter were added successively to sperm cells in the vas deferens. The first type was periodic acid - Schiff (PAS)-positive and apparently induced spermiogenesis when present in a sufficiently large amount. However, a smaller amount of this amorphous matter was sufficient to form the basal pellicle of spermatophores. The second type was PAS-negative and thickened the wall of spermatophores. Immature and mature spermatids were usually enclosed within distinct spermatophores. Enclosed mature spermatids were connected together by bridges formed by Feulgen-positive spikes coated and extended by PAS-positive amorphous matter. Once broken, the bridges appeared as arms that radiated from a spermatid. Peripheral mature spermatids were furthermore linked to the spermatophore wall by threads of PAS-positive amorphous matter. The bridges and threads may form a pathway for the diffusion of extraneous substances through the spermatophore wall to the innermost cells.
Cod courtship song: a song at the expense of dance?
Authors: Engen Frode , Folstad Ivar
Published: April 2011

Sexually selected characters may reveal information about individual quality during mate choice. Fin display and sound emitted with the aid of specific drumming muscles are characters described as being of importance in the reproductive behaviour of cod (Gadus morhua L.). We examined whether the mass of drumming muscles or fin size was sexually dimorphic, and whether these characters could provide information about male cod that was potentially of benefit to mate-seeking females. The mass of drumming muscles, but not fin size, was sexually dimorphic, with males having larger muscles than females. Neither the mass of drumming muscles nor fin size apparently revealed information about traits that may be associated with parasite resistance in males (i.e., parasite intensities and leukocyte densities). However, variation in fertilization potential (i.e., spermatocrit level) among males was related to both mass of drumming muscles and fin size. Thus, by evaluating sound and fin size, mate-seeking females may obtain information about fertilization ability among males. This may be of particular importance for females in a species whose eggs commonly remain unfertilized. Furthermore, males with large drumming muscles and small fins had low spermatocrit levels. This may reflect reductions in sperm density resulting from frequent ejaculations by attractive males. A costly allocation of resources for the development of drumming muscles at the expense of fin muscles used for propulsion is presented as a tentative explanation as to why females should pay attention to these particular traits during courtship. Increased investment in "song" may thus appear at the expense of "dance."
Inshore and offshore bottlenose dolphin (Tursiops truncatus) communities distinguished by association patterns near Grand Bahama Island, Bahamas
Authors: Rossbach Kelly A , Herzing Denise L
Published: April 2011

Little is known about the behavior of offshore dolphin populations. Our purpose was to distinguish and describe stable social groups of bottlenose dolphins (Tursiops truncatus) between inshore and offshore West End, Grand Bahama Island (26°42'N, 79°00'W). Photoidentification was conducted from May to September, 1994 to 1996. A simple ratio index described association patterns between dolphins. Multidimensional scaling of association indices (n = 1711 dolphin pairs) distinguished two dolphin communities consisting of 28 dolphins (19 of known sex) found inshore and 15 dolphins (12 of known sex) found greater than or equal to 27 km offshore. Eight of the 15 offshore dolphins were opportunistically photographed in the same region between 1986 and 1990. The two communities were found at different water depths (Mann-Whitney U test, p < 0.01), over distinct bottom types (Kruskal-Wallis test, p < 0.01), and used different bottom-foraging strategies. Long-term site fidelity of up to 10 years and repeated dolphin associations of up to 8 years occurred greater than or equal to 27 km from shore. Dolphins sighted greater than or equal to 15 times averaged 48 associates (SD = 11, n = 28). A dolphin's closest associate was of the same gender 74% of the time. This study is the first to report long-term site fidelity and association patterns of bottlenose dolphins found far from shore.
The development of diving behavior in juvenile Weddell seals: pushing physiological limits in order to survive
Authors: Burns Jennifer M
Published: April 2011

In juvenile phocids, the successful transition from nursing to independent foraging is contingent upon the development of adequate diving skills within the limited time between weaning and the depletion of body reserves. Yet, because juvenile seals are unable to remain submerged for as long as adults, owing to their smaller size, higher metabolic rates, and lowered oxygen stores, their behavioral options are likely constrained. To determine how such limitations might influence foraging strategies, we studied the development of diving behavior and physiology in Weddell seal (Leptonychotes weddellii) juveniles, using a combination of time-depth recorders, satellite-linked dive recorders, and morphological and physiological measurements (mass and blood chemistry). Time-depth recorder data indicated that the average depth, duration, and frequency of dives made by pups increased rapidly in the period from birth through weaning, but slowed soon thereafter. While preweaning increases in these parameters were correlated with seal age, postweaning increases in dive capacity were gradual and were probably the result of slower changes in mass and body composition. In weaned pups and yearlings, dive frequency and time underwater increased with age and (or) mass. Despite their smaller size and lower absolute energy requirements, the amount of time juveniles spent in the water was similar to that spent by adults. However, because juveniles were unable to remain submerged as long as adults and because most foraging dives were deep, juveniles were unable to spend an equivalent amount of time at the foraging depths. This difference was evident even though juveniles dove much closer to their anaerobic threshold than did adults. These findings support the hypothesis that the foraging efficiency of younger seals is reduced relative to that of adults, owing to physiological and morphological constraints on aerobic dive duration, and suggests that low juvenile survival might result from behavioral constraints.