bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Cryptobia salmositica on feeding, body composition, and growth in rainbow trout
Authors: Lowe-Jinde L. , Zimmerman A. M.
Published: August 2008

Rainbow trout, Oncorhynchus mykiss, were experimentally infected with the blood haemoflagellate Cryptobia salmositica. The parasitic infection significantly decreased voluntary meal consumption and growth. An analysis of the proximate body composition showed that the Cryptobia infection was associated with increased water, protein, and ash content, while the fat content was reduced. Also, higher mortality and a higher level of parasitemia were observed in fish stock from one local hatchery compared with that in fish stock from another local hatchery.
Occurrence and ecology of Lophopodella carteri (Hyatt) and other freshwater Bryozoa in the lower Ottawa River near Montréal, Quebec
Authors: Ricciardi Anthony , Lewis David J.
Published: August 2008

Seven species of freshwater Bryozoa (Ectoprocta) were collected from the lower Ottawa River near Montréal, Quebec: Lophopodella carteri (Hyatt), Plumatella repens (Linnaeus), Hyalinella punctata (Hancock), Paludicella articulata (Ehrenberg), Fredericella indica Annandale, Pectinatella magnifica (Leidy), and Cristatella mucedo Cuvier. Lophopodella carteri is reported from Canada for the first time, and this record represents a 300-km northward extension of its known range. Plumatella repens, H. punctata, F. indica, and P. articulata are new records for the province of Quebec. Bryozoan colonies were commonly associated with each other and with other macroinvertebrates, including freshwater sponges, molluscs, turbellarians, chironomid larvae, and caddisfly larvae. Larval caddisflies, Ceraclea (Trichoptera: Leptoceridae), and the microturbellarian Stenostomum (Turbellaria: Catenulida) were predators of living bryozoan colonies.
Blood parasites of black ducks and other anatids from Labrador and insular Newfoundland
Authors: Bennett Gordon F. , Stotts Vernon D. , Bateman Myrtle C.
Published: August 2008

A total of 510 ducks of seven species from Labrador was examined for blood parasites; 76% of the birds were parasitized by one or more haematozoa. Leucocytozoon simondi occurred in 91% whereas haemoproteids occurred in only 11% of the infected ducks. Green-winged teal and black ducks were the most heavily parasitized of the anatid species, with a prevalence of infection higher than that of either pintails or mallards. Only 49% of the same species of ducks from western Newfoundland were infected with blood parasites; haemoproteids, rather than leucocytozoids, were the most commonly encountered blood parasite. Ducks from the eastern side of Newfoundland are still blood parasite free.
Immunohistochemical localization of somatostatin within the pineal gland of metamorphosing lampreys, Petromyzon marinus L.
Authors: Cheung Richard , Youson John H.
Published: August 2008

The distribution and onset of immunoreactivity to anti-somatostatin-14 and anti-somatostatin-34 within the pineal gland of metamorphosing lampreys, Petromyzon marinus, were examined by immunohistochemistry. No staining was observed with anti-somatostatin-34. Somatostatin-14 immunoreactive cells were not found in the larval pineal complex but were present within the pineal pellucida of the pineal gland beginning at stage 5 of transformation and through the final two stages (6 and 7) of metamorphosis. No immunoreactivity was seen in the parapineal gland. The time of onset of this immunoreactivity in the pineal gland may denote an important transition period from larval to adult life.
Effect of ectoparasitism by larvae of the blow fly Protocalliphora parorum (Diptera: Calliphoridae) on nestling House Wrens, Troglodytes aedon
Authors: Johnson L. Scott , Eastman Marjorie D. , Kermott L. Henry
Published: August 2008

We investigated the effect of ectoparasitism by hematophagous larvae of the blow fly Protocalliphora parorum on nestling House Wrens (Troglodytes aedon) over 2 years in north-central Wyoming, U.S.A. Approximately 85% of wren nests contained P. parorum larvae. Mean parasite load was approximately 10 larvae per nestling. Nestling tarsus length, primary feather length, and hematocrit measured just before fledging did not differ significantly with parasite load. However, parasitized birds weighed approximately 8% more than unparasitized birds just prior to fledging. Parasites possibly delay the recession in weight that normally occurs as tissues mature late in the nestling stage. Delayed development may result in increased nestling or fledgling mortality.
Cannibalism of nestling American kestrels by their parents and siblings
Authors: Bortolotti Gary R. , Wiebe Karen L. , Iko William M.
Published: August 2008

We examined the frequency of cannibalism of nestling American kestrels (Falco sparverius) in north-central Saskatchewan. We investigated human disturbance and food shortages as possible causes of it. Cannibalism of nestlings by their parents and siblings was confirmed by observation and by the presence of partially eaten carcasses, or inferred from the sudden disappearance of a nestling between frequent nest checks. Cannibalism occurred at 8% of 48 nests in 1988, and 18% of 92 nests in 1989. Not all nestlings that died were cannibalized. Where nestling mortality occurred, carcasses were eaten in at least 20% of nests in 1988, and 63% of nests in 1989. The chicks that were cannibalized died at a significantly younger age than those that died but were not cannibalized. The mass and age of the parent and the laying date were not associated with the occurrence of cannibalism. We found no strong evidence of a causal link between human disturbance and nestling mortality or cannibalism; however, the abundance of small mammal prey was inversely related to the frequency of cannibalism between years, and there were fewer prey and lower prey delivery rates in territories where cannibalism occurred than in territories where nestling mortality did not occur. The fact that some nestlings died but were not eaten suggests that such mortality was unrelated to food shortages. The food advantage of cannibalism may not outweigh potential disadvantages such as disease transmission.
Vocal traditions among resident killer whales (Orcinus orca) in coastal waters of British Columbia
Authors: Ford John K. B.
Published: August 2008

Underwater vocalizations were recorded during repeated encounters with 16 pods, or stable kin groups, of resident killer whales (Orcinus orca) off the coast of British Columbia. Pods were identified from unique natural markings on individuals. Vocal exchanges within pods were dominated by repetitious, discrete calls. Pods each produced 7–17 (mean 10.7) types of discrete calls. Individuals appear to acquire their pod's call repertoire by learning, and repertoires can persist with little change for over 25 years. Call repertoires differed significantly among pods in the resident population. The 16 pods formed four distinct acoustic associations, or clans, each having a unique repertoire of discrete calls, or vocal tradition. Pods within a clan shared several call types, but no sharing took place among clans. Shared calls often contained structural variations specific to each pod or group of pods in the clan. These variants and other differences in acoustic behaviour formed a system of related pod-specific dialects within the vocal tradition of each clan. Pods from different clans often travelled together, but observed patterns of social associations were often independent of acoustic relationships. It is proposed that each clan comprises related pods that have descended from a common ancestral group. New pods formed from this ancestral group through growth and matrilineal division of the lineage. The formation of new pods was accompanied by divergence of the call repertoire of the founding group. Such divergence resulted from the accumulation of errors in call learning across generations, call innovation, and call extinction. Pod-specific repertoires probably serve to enhance the efficiency of vocal communication within the group and act as behavioural indicators of pod affiliation. The striking differences among the vocal traditions of different clans suggest that each is an independent matriline.
Susceptibility of blue-winged teal, gadwall, and lesser scaup ducklings to experimental infection with Streptocara crassicauda
Authors: Laberge R. J. A. , McLaughlin J. Daniel
Published: August 2008

Blue-winged teal, gadwall, and lesser scaup ducklings were exposed experimentally to identical doses of Streptocara crassicauda larvae. The heaviest infections developed in the teal. Gadwall were also highly susceptible and infection levels were generally similar to those in teal. Lesser scaup developed comparatively light infections. Lesions were restricted to the gizzard and occurred in the softer areas of the lining under the tendinous surfaces. Nematodes were generally confined to the lesions in scaup, but not in teal or gadwall. In these two species, they were also found elsewhere under the softer portions of the lining and, to a lesser extent, under the grinding plates. Teal and gadwall developed more and larger lesions because of the greater number of nematodes that established. When corrected for worm number, no difference in lesion size was found among the three species.
Parental care in the common eider (Somateria mollissima): factors affecting abandonment and adoption of young
Authors: Bustnes Jan O. , Erikstad Kjell E.
Published: August 2008

Parental care in common eiders (Somateria mollissima) was studied during three field seasons in northern Norway. Forty-two percent of the females were found to abandon their brood. Abandonment and tending of broods and crèches were not obligate individual strategies, but changed between years. Females abandoning their young laid smaller clutches and had a lower body weight at hatching than brood- and crèche-tending females, indicating that they were in poor body condition. This supports the hypothesis that abandoning the brood is a salvage strategy in which energetic stress limits females' ability to care for their young. Young of "abandoners" seemed to have a lower survival rate than young of "tenders," which suggests a reproductive cost of abandoning the young. Forty-seven percent of tagged ducklings were found with females other than their mother. Twenty-seven percent of the brood- and crèche-tending females lost young to other females, but never more than one duckling. Adoptions of foreign ducklings, above the normal brood size of four, did not lead to greater parental effort, and duckling survival was similar among broods and crèches of different sizes. This suggests that adoptions may be of neutral adaptive value. Two females often formed stable crèches, but duckling survival was not significantly different from that in broods and crèches with single females.
Role of enzyme binding in muscle metabolism of the goldfish
Authors: Duncan John A. , Storey Kenneth B.
Published: August 2008

Regulation of glycolytic metabolism in muscle by the reversible association of enzymes with the particulate fraction of the cell was assessed in heart and white skeletal muscle of the goldfish Carassius auratus. Three physiological states were compared: rested aerobic controls, 21 h of anoxia exposure in water bubbled with N2 and CO, and exhaustive swimming. Heart muscle responded to the anoxia exposure with an increase in the percentage bound for phosphofructokinase (PFK), aldolase, and pyruvate kinase, the greatest increase being for PFK (from 35 to 48%). When fish swam to exhaustion, however, no changes in the percentage bound occurred for the eight enzymes assayed in heart. In white muscle neither anoxia nor exhaustive swimming altered the binding of the eight enzymes to the particulate fraction of the cell, except for a significant decrease in the percentage of alcohol dehydrogenase bound in anoxic muscle. PFK binding was particularly high in white muscle (63–72% bound, assessed by two methods). PFK binding was sensitive to pH in both organs, with binding increasing as pH decreased. This suggests that binding of PFK could be enhanced when metabolism is highly dependent on glycolytic ATP production due to the fall in cellular pH as a result of metabolic acidosis.
Restriction fragment analysis of mitochondrial DNA in Common Murres, Uria aalge, from four Norwegian seabird colonies
Authors: Moum Truls , Erikstad Kjell Einar , Bjørklid Eirik
Published: August 2008

Alcid species (auks) breed in a restricted number of large seabird colonies and are considered highly philopatric. Mitochondrial DNA (mtDNA) of Common Murres, Uria aalge, from four Norwegian colonies was investigated by restriction analysis to assess the amount of geographic population structure and genetic variability in a colonial breeder. Eleven restriction endonucleases revealed 13 mtDNA genotypes among 51 individuals. Genetic diversity was low, with an average of 0.11% (range 0.0–0.55%) sequence divergence between all individuals. Population divergence within the surveyed region seems to be minimal, demonstrated by the low levels of sequence divergence between colonies and lack of spatial structuring of genotypes. Such results can be expected if birds originated from a smaller ancestral population during glaciation, and may have been reinforced by repeated population bottlenecks and considerable gene flow between colonies.
Hairworm (Nematomorpha: Gordioidea) parasites of New Zealand wetas (Orthoptera: Stenopelmatidae)
Authors: Poinar Jr. George O.
Published: August 2008

The New Zealand hairworms (Nematomorpha: Gordioidea) Gordius dimorphus n.sp., Euchordodes nigromaculatus n.sp., and Gordionus diblastus (Örley) are described or redescribed as parasites of the stenopelmatid (Orthoptera) genera Deinacrida, Hemiandrus, Zealandosandrus, and Hemideina. Hairworm larvae are described from aquatic insect paratenic hosts. It is assumed that when these hosts are eaten by wetas, the parasites invade the body cavity of the latter and develop to maturity. On the basis of biogeographical and paleontological evidence it is likely that weta parasitism by hairworms extends back to the Mesozoic.
Malacobdella siliquae sp.nov. and Malacobdella macomae sp.nov., commensal nemerteans from bivalve molluscs on the Pacific coast of North America
Authors: Kozloff Eugene N.
Published: August 2008

Two species of Malacobdella, found in the mantle cavity of bivalve molluscs on the Pacific coast of North America, are described. One of them, M. siliquae, lives in Siliqua patula. The other, M. macomae, has two known hosts, Macoma secta and M. nasuta. The taxonomy of known species of the genus Malacobdella is discussed.
Revision of the genus Anophryocephalus Baylis, 1922 from pinnipeds in the Holarctic, with descriptions of Anophryocephalus nunivakensis sp.nov. and A. eumetopii sp.nov. (Tetrabothriidae) and evaluation of records from the Phocidae
Authors: Hoberg Eric P. , Adams Ann M. , Rausch Robert L.
Published: August 2008

Anophryocephalus Baylis, 1922 is emended to include tetrabothriid cestodes with intricate scolices (paired auricular appendages and bothridial operculae), complex genital atria (muscular chamber ventral to the vagina; muscular pad adjacent to the aperture of the male canal), and atrophy of the dorsal osmoregulatory system. Anophryocephalus anophrys (type), A. skrjabini, and A. ochotensis are redescribed. Anophryocephalus nunivakensis sp.nov., from Phoca largha, has bothridial operculae with broad anterior apertures, an ovoid cirrus sac (57–95 μm in diameter), a ventrolaterally directed male canal (26–44 μm long in mature segments), and 26–56 testes. Anophryocephalus eumetopii sp.nov., from Eumetopias jubatus, has bothridial operculae with narrow, slitlike, diagonally directed apertures, a spheroidal cirrus sac (51–72 μm in diameter), a prominent genital papilla and ventrolaterally directed male canal (36–51 μm long in mature segments), and 32–66 testes. Postlarval ontogeny of the scolex among some species of Anophryocephalus appears similar to that known for Tetrabothrius spp., suggesting uniformity in morphogenesis of the holdfast among the Tetrabothriidae. Anophryocephalus spp. are typical parasites of pinnipeds in the Holarctic, and contrary to previous reports, A. skrjabini and A. ochotensis are exclusively parasites of Phoca spp. and Eumetopias jubatus, respectively, at high latitudes in the North Pacific basin and Bering Sea.
Summer foraging by spruce grouse: implications for galliform food habits
Authors: Franceschi P. F. De , Boag D. A.
Published: August 2008

Observations of foraging birds showed that the summer diet of adult and juvenile spruce grouse (Dendaragapus canadensis) in southwestern Alberta included 31 taxa of fungi, vascular plants, and animals. The genus Vaccinium was confirmed as the major food source for these grouse during summer. For the first time, however, conifer needles and fungi were recorded as important components of the diet at this time of the year. The latter observations raised questions about the potential for bias, particularly in terms of the type of the food ingested and the time of day when it was consumed, in studies of the food habits of galliforms that are based only on analyses of crop contents.
Diet composition and prey selection in the lizard Lacerta monticola
Authors: Pérez-Mellado Valentin , Bauwens Dirk , Gil Martin , Guerrero Fátima , Lizana Miguel , Ciudad Maria-José
Published: August 2008

We studied diet composition and prey selection in the lizard Lacerta monticola throughout its activity season. The most important prey groups in terms of numbers were Coleoptera, Diptera, Formicidae, and Araneae. Comparison of diet composition in the adult lizards with estimates of prey availability indicated that lizards exhibited precisely defined patterns of prey selection. Electivities were negative for prey < 3 mm in length and generally positive for larger prey, despite the higher relative abundance of the former group in the environment. Electivity scores for individual prey taxa were positively correlated with their length, and lizards preferentially consumed larger individuals belonging to the taxa containing smaller animals. Relative availability of the four major prey taxa fluctuated considerably throughout the year. In spite of these changes, monthly rates of consumption of Araneae and Diptera remained almost constant. Variations in monthly electivity scores were negatively correlated with relative availability of three (Coleoptera, Diptera, and Araneae) of the four major prey taxa. These results fit the predictions of prey-selection models based on nutrient constraints.
Selection of calving sites by Porcupine herd caribou
Authors: Fancy S. G. , Whitten K. R.
Published: August 2008

Characteristics of 305 calving sites used by 131 different radio-collared caribou (Rangifer tarandus) cows from the Porcupine herd in northeastern Alaska and the northern Yukon Territory were investigated between 1983 and 1990 to determine the factors influencing calving site selection. Cows selected areas north of the foothills primarily to reduce exposure of calves to predators. Sites dominated by Eriophorum tussocks were selected secondarily for access to newly emerging vegetation. Highest calf mortality occurred in years when snowmelt was relatively late and calving occurred closer to the foothills and in Canada. Industrial development of the coastal plain of the Arctic National Wildlife Refuge could increase calf mortality if calving were displaced south and east of potential development areas.
Structure of the gill during reproduction in the unionids Anodonta grandis, Ligumia subrostrata, and Carunculina parva texasensis
Authors: Richard Pamela E. , Dietz T. H. , Silverman H.
Published: August 2008

This study characterizes the morphological modifications of the gill that establish the functional isolation of the central water channels into brood chambers during reproduction. The anodontids use the entire lateral demibranch for reproduction. The water channels are permanently subdivided by additional septa, resulting in more channels, but they are about one-third the size of those in the medial gill. Immediately before egg deposition, each water channel is subdivided by the formation of two small secondary water channels that receive water from the water canals, and a large brood chamber with no direct exposure to the circulating pond water. The secondary water channels disappear 1 or 2 weeks after release of the larvae. The septal tissue at the suprabranchial chamber becomes enlarged after egg deposition and seals the dorsal opening of the brood chamber from the exhalant water. The lampsilids do not form secondary water channels and the eggs are deposited in the central water channel of the posterior half of the lateral demibranch. The septal tissue enlarges at the suprabranchial chamber after egg deposition. In addition, muscular tissue near the ostial opening of the canal and at the canal – channel junction is able to constrict the canal orifice. In all species studied, the modified gill allows little if any ambient pond water into the brood chamber, and the aqueous environment is under the control of the maternal tissues.
Extensive use of the Fraser River basin as winter habitat by juvenile chinook salmon (Oncorhynchus tshawytscha)
Authors: Levings C. D. , Lauzier R. B.
Published: August 2008

Habitat in the low-water channel of the mainstem Fraser River and larger tributaries during winter may be an unappreciated factor influencing production of stream-type chinook salmon (Oncorhynchus tshawytscha) in this system. Data from electrofishing surveys showed that shorelines were used by juvenile chinook from river km 110 to km 770. Almost the entire mainstem was therefore probably winter habitat, and major tributaries such as the Thompson, Quesnel, and Nechako rivers were also used. Estimated chinook density on the mainstem Fraser increased with distance upstream (maximum 0.30 m−2 at km 750 (Prince George)), but the highest density (0.99 m−2) in the surveys was observed on the Thompson River at Spences Bridge. The mean size of juvenile chinook decreased with distance upstream on the Fraser, ranging from 97 mm at km 110 to 65 mm at km 770. Chinook juveniles were feeding on Diptera, Trichoptera, and Plecoptera in winter. Some apparent growth was observed in the lower Fraser in early winter.
The feeding ecology of mountain chickadees (Parus gambeli): patterns of arthropod prey delivery to nestling birds
Authors: Grundel Ralph , Dahlsten Donald L.
Published: August 2008

The diet of nestling mountain chickadees (Parus gambeli) (55 694 items in 34 730 feeding trips) is summarized. Larval Hymenoptera, Lepidoptera, and adult Coleoptera were the most common prey in the nestlings' diet. A single prey item was usually delivered per trip. Significant intersexual differences in delivery of specific prey types were rare; intersexual differences in overall diets declined with nestling age. Prey delivered by individual parents exhibited decreasing day to day variation as nestlings aged. Frequency of prey preparation declined with nestling age, with feeding frequency, and especially with increasing number of prey delivered per trip. Delivery of some prey, such as spiders, changed as a function of nestling age, whereas delivery of other prey was more directly related to calendar date and, by implication, to prey availability and environmental conditions. Take of most prey exhibited significant diurnal variation related to prey behaviour and to periodicities in nestling hunger state. Time spent waiting at the nest entrance often took up a greater portion of each foraging trip, and was more variable, than prey preparation time or travelling time between nest and foraging site and should be incorporated into foraging models.
Experimental evaluation of age, body size, and experience in determining territory ownership in willow ptarmigan
Authors: Martin Kathy
Published: August 2008

During 1981–1984, 18% of resident males in a population of willow ptarmigan at La Perouse Bay, Manitoba, Canada, were unpaired at onset of breeding, whereas all resident females acquired males. Territory ownership and pair bonds were very stable within seasons, with only three territory and mate takeovers by males occurring among 275 pair-years. I present data on origins, age, body size and mass, familiarity with the site, and breeding experience for paired and unpaired males, and on responses of both sexes to vacancies created by the experimental removal of mates. Of 61 paired males (territory owners) removed after onset of incubation, 70% were replaced by either unpaired males or, to a lesser extent, by paired territorial neighbours. When seven original owners were released after over a week in captivity, five regained their territories and mates, displacing replacement males quickly. Initial territorial dominance was related to age, body size, site familiarity, and breeding experience, as original paired owners were older, larger, and more likely than unpaired males to have resided on the area and to have been paired in a previous year. However, neither age, body size, body mass, familiarity with the area, nor territorial or breeding experience predicted which unpaired males obtained territories and mates when opportunities were created. In contrast to males, females killed during incubation were not replaced. In other populations of willow ptarmigan where removals were done about 1 month earlier in the breeding season, females replaced at vacancies and males that replaced were more likely to be territorial paired males expanding their boundaries than unpaired males.
Body temperature regulation and oxygen consumption in young chicks fed thyroid hormone
Authors: Snyder Gregory K. , Coelho Joseph R. , Jensen Dalan R.
Published: August 2008

In chicks the ability to regulate body temperature to adult levels develops during the first 2 weeks of life. We examined whether the ability of young chicks to regulate body temperature is increased by elevated levels of the thyroid hormone 3,3′5-triiodothyronine. By 13 days following hatch, body temperatures of chicks were not significantly different from those expected for adult birds. Furthermore, at an ambient temperature of 10 °C, 13-day-old control chicks were able to maintain body temperature, and elevated serum thyroid hormone levels did not increase rates of oxygen consumption or body temperature above control values. Six-day-old chicks had body temperatures that were significantly lower than those of the 13-day-old chicks and were not able to regulate body temperature when exposed to an ambient temperature of 10 °C. On the other hand, 6-day-old chicks with elevated serum thyroid hormone had significantly higher rates of oxygen consumption than 6-day-old control chicks, and were able to maintain constant body temperatures during cold exposure. The increased oxygen consumption rates and improved ability to regulate body temperature during cold exposure were correlated with increased citrate synthase activity in skeletal muscle. Our results support the argument that thyroid hormones play an important role in the development of thermoregulatory ability in neonate birds by stimulating enzyme activities associated with aerobic metabolism.
The digestive efficiency of insectivorous bats
Authors: Barclay Robert M. R. , Dolan Mary-Anne , Dyck Alvin
Published: August 2008

To analyze foraging strategies and energy budgets, a knowledge of the digestive efficiency of animals is essential. There are no such data for insectivorous bats feeding on natural prey. We fed moths of various sizes to bats of three species, Myotis lucifugus, M. evotis, and M. volans and calculated digestive efficiencies using a micro-bomb calorimeter to measure the energy content of prey, uneaten remains and feces. Bats typically did not consume the legs or wings of the moths, and occasionally also rejected the heads. Despite this, all three species had mean digestive efficiencies between 75 and 78%, significantly lower than that of individuals fed mealworm larvae in this and previous studies (88–90%). There was a significant positive correlation between moth size and digestive efficiency, with small moths (20 mg) being digested at under 75% efficiency. Since most natural prey are even smaller than that and are typically consumed whole (including legs and wings), and many are likely less digestible than moths, we predict that actual digestive efficiencies realized by bats in the field will be under 70%. Variation in the efficiency of digestion of different prey may have significant implications for prey selection by bats. In addition, our results suggest that to meet energy demands, bats must consume greater quantities of prey than was previously estimated, and likely consume more than their own body weight per night during times of high energy demand, such as lactation.
Song repertoires of Harris' sparrows (Zonotrichia querula)
Authors: Shackleton Scott A. , Ratcliffe Laurene , Horn Andrew G. , Naugler Christopher T.
Published: August 2008

The songs of 34 male Harris' sparrows were recorded at Churchill, Manitoba. The songs are composed of one to three whistled notes, all at the same frequency. Individuals sing from one to three song types, each at a discrete frequency. Males are very accurate at returning to the same frequency, both within a bout and between days. Individuals seem to structure their repertoire on the basis of the frequency ratio between types, rather than on the absolute frequency of each type. Males responded to playback of a 3-kHz song with the song in their repertoire that was closest to it in frequency. We suggest that the frequency ratio between song types may be species specific, whereas the absolute frequency of song types may facilitate individual recognition. This species has been previously described as having only a single song type. Our study and other recent work suggest that there is no sharp distinction in the wild between bird species with single and multisong repertoires.
Sporogonic development of Haemoproteus meleagridis (Haemosporina: Haemoproteidae) in Culicoides edeni (Diptera: Ceratopogonidae)
Authors: Atkinson Carter T.
Published: August 2008

Mature oocysts of Haemoproteus meleagridis developed in specimens of Culicoides edeni within 3–6 days after the midges took a blood meal from an infected domestic turkey. Approximately 50 sporozoites budded from the surface of a single sporoblast body. Sporogonic development was similar to that of reptilian, avian, and mammalian haemoproteids that are transmitted by ceratopogonid and tabanid flies, but unlike that of hippoboscid-transmitted species in birds, which form large, slowly developing oocysts with multiple sporoblast bodies. Ultrastructural features of developing oocysts included nuclei with prominent nucleoli, mitochondria, and sandwich-like arrays of crystalloid particles and smooth endoplasmic reticulum (ER) that were present on the outer surface of developing lipid droplets during early stages of sporogony. During budding of sporozoites, crystalloid particles measuring 30–40 nm in diameter were associated with the inner membrane complex of the sporozoite pellicle, arranged in rows between subpellicular microtubules. Mature sporozoites contained an apical complex composed of a polar ring with two anterior apical rings, from two to eight elongate rhoptries, 22 evenly spaced subpellicular microtubules, and a small anterior crystalloid body. Morphological similarities between the ER–crystalloid arrays and the ER–microperoxisome arrays that have been described in cells actively engaged in lipid biosynthesis suggest that the crystalloid body contains enzymes important in lipid metabolism.
A genetic polymorphism in hemoglobins of chinook salmon, Oncorhynchus tshawytscha
Authors: Fyhn Unni E. H. , Withler Ruth E.
Published: August 2008

A genetic polymorphism with three phenotypes is described for the anodally migrating hemoglobins of adult chinook salmon (Onchorhynchus tshawytscha) from British Columbia, Canada. A genetic model with the genotypes DD, DH, and HH is suggested, on the basis of Hardy–Weinberg genotypic frequencies, in samples of adult chinook salmon from three stocks, and on Mendelian genotypic frequencies among progeny of single-parent crosses. Allelic frequencies differed among stocks. The polymorphism may result from a dimorphism in one or both of the tentatively called β-chain loci, with allele D encoding a chain βFf and allele H encoding a chain βFs. The two β-loci may be individually regulated. The locus tentatively referred to as α is monomorphic, as are the minimum of three or four loci that encode the globins of the cathodal hemoglobins. The cathodal and anodal hemoglobins had no globins in common.
Sex pheromone gland of the female tiger moth Holomelina lamae (Lepidoptera: Arctiidae)
Authors: Yin Lucy R. S. , Schal Coby , Cardé Ring T.
Published: August 2008

Airborne sex pheromone from the female arctiid moth Holomelina lamae originates from a pair of internal glands located dorsally at the female's abdominal tip, above the ovipositor. Each gland opens externally to a dorsal pore, with both pores being situated near the junction of abdominal segments 8 and 9. The lumen of each gland is lined by cuticle with a profusion of spines; these presumably prevent collapse of the tubes. Beneath the cuticle is a layer of pear-shaped epithelial cells. In ultrastructural examination, these cells are characterized by microvilli apically, a large nucleus and numerous organelles in the central region, and a highly convoluted membranous area basally. The tubular gland structure with internal spines provides a reservoir for sequestering the several micrograms of pheromone found in this small moth. It is suggested that the function of these spines is in pheromone emission.
Habitat selection by foraging White Storks, Ciconia ciconia, during the breeding season
Authors: Alonso Juan C. , Alonso Javier A. , Carrascal Luis M.
Published: August 2008

Foraging habitat selection by breeding White Storks (Ciconia ciconia) was studied at two contrasting areas in Spain, in relation to physical features of the terrain, food availability, and distance to the colony. In the first area, where storks captured mainly orthopterans, they selected tall-grass pastures and recently ploughed cereal fields, which were the habitats with highest densities and largest average sizes of prey. In the second area, where storks preyed almost exclusively on earthworms, flooded and open ash groves with short grass and high densities of earthworms were the preferred habitat. In this area, marked storks dispersing farther to feed in selected open ash groves more often than in dense ones. Foraging bouts, were longer, aggregations were larger, and food intake rates were greater, in open ash groves than in dense ones, owing to greater earthworm availability and accessibility. Depletion of earthworms led to an increased distance of dispersal to forage in the second area, but not in the first, where because of rapid reproduction of orthopterans, the birds were not forced to forage at greater distances later in the season.
Sexual differences in color and color change in wood frogs
Authors: King Richard B. , King Bethia
Published: August 2008

An observer-free method of color classification was used to determine whether wood frogs, Rana sylvatica, exhibit sexual differences in color and color change. Males and females captured from breeding aggregations differed significantly in color: females reflected a greater amount of long-wavelength (yellow–red) light and less short-wavelength (blue–green) light than males. The color difference was not just a result of differences in the state of physiological color change at the time of capture but persisted for a month after capture. Males and females also differed in their color-change responses to black and white backgrounds: both sexes changed in brightness, but only males changed in the relative amount of light reflected at different wavelengths. Wood frog color may function in predator avoidance through crypsis. There was a good match between frogs and some of the leaves from the leaf litter surrounding the breeding ponds. Hypotheses for the development of sexual differences in wood frog color include sexual differences in availability of pigment and pigment precursors, morphological color change, and evolutionary response to different selection pressures.
Female morphs of the damselfly Enallagma boreale Selys (Odonata: Coenagrionidae): a benefit for androchromatypes
Authors: Forbes Mark R. L.
Published: August 2008

Females of the coenagrionid damselfly Enallagma boreale Selys occur as three distinct colour morphs at a study site in eastern Ontario, Canada; > 65% are blue (termed androchromatypes) like the conspecific male, ca. 30% are green, and < 5% have both blue and green on their abdomen. I provide experimental evidence which suggests that one advantage of androchromatypism is avoidance of harassment from heterospecific males of the congeneric damselfly Enallagma ebrium (Hagen).
Sexing beluga whales (Delphinapterus leucas) by means of DNA markers
Authors: Brown Moira W. , Helbig Ree , Boag Peter T. , Gaskin David E. , White Bradley N.
Published: August 2008

Few methods are available for determining the sex of free-ranging individual whales, dolphins, and porpoises of species that are not obviously sexually dimorphic. We have developed a technique for sexing beluga whales (Delphinapterus leucas) by using a Y-chromosome-specific DNA restriction fragment. Genomic DNA was extracted from liver samples of 18 beluga whales (9 males, 9 females) sexed at dissection. DNA from males and females was digested with five restriction enzymes, electrophoresed, and transferred to membranes by Southern blotting. When probed with the labelled human Y-chromosome zinc finger protein gene probe pDP1007, male-specific bands and bands common to both sexes, but more intense in females than in males, were observed. The DNA digested with EcoRI provided the clearest sex-discriminating banding pattern. Even when DNA of various qualities digested with EcoRI was used, all the males showed a 3.4-kilobase (kb) band, presumably from the Y-chromosome, as well as a 2.1-kb band. Females showed the 2.1-kb band, but all lacked the 3.4-kb band. This 3.4-kb EcoRI male-specific band permits unambiguous sex determination, which will facilitate examination of sex-related differences in population structure and habitat use of belugas, which have important implications for management decisions.
Cardiac function and circulation in hagfishes
Authors: Forster Malcolm E. , Axelsson Michael , Farrell Anthony P. , Nilsson Stefan
Published: August 2008

The hagfish circulation contains a high volume of blood (180 mL∙kg−1) and is remarkable for the number of accessory pumps. Cardiac output from the branchial heart of hagfishes is comparable to that of elasmobranch and most teleost fishes, but blood pressures are considerably lower than in any other vertebrate group. Cardiac output is extremely sensitive to both venous return and ventral aortic pressure (afterload). Owing to the low arterial blood pressures, myocardial power output is lower than for any other vertebrate heart. The concomitant low energy requirement of the myocardium allows ATP generated anaerobically through glycolysis to maintain cardiac output during severe hypoxia. In vivo and in vitro administration of adrenergic agonists and antagonists increase and decrease cardiac performance, respectively. This suggests that the catecholamines that are stored beneath the endothelium of the branchial and portal hearts are involved in the tonic control of cardiac function.
Metabolic and cardiac scope of high energy demand teleosts, the tunas
Authors: Brill Richard W. , Bushnell Peter G.
Published: August 2008

The maximum aerobic metabolic rates of tunas are far above those of other fishes. In this review we attempt to define features of the cardiovascular system that may account for this extreme performance. Tuna hearts are much larger than those of most other fishes and are half the mass of those of similarly sized mammals; however, the ratio of compact to spongy myocardium is not (except for one tuna species) higher than in other active teleosts. Myocardial aerobic enzyme activity levels are not significantly elevated. The cardiac outputs of spinally blocked skipjack tuna (Katsuwonus pelamis) and yellowfin tuna (Thunnus albacares) are roughly 4 times those of other active teleosts. Ventral aortic blood pressures are the highest among all fishes (more than twice those of rainbow trout (Oncorhynchus mykiss, formerly Salmo gairdneri)), and appear to be due to a high resistance to blood flow in the gills, since dorsal aortic blood pressures are not exceptional. Heart rates, cardiac output, and ventilation volume are high, but gill ventilation and perfusion appear to be well matched (i.e., gill ventilation: perfusion conductance ratios of ≈1). Blood hemoglobin concentrations of tunas are elevated, essentially identical with those of humans and twice those seen in other fishes. Because their blood oxygen carrying capacity is high and because skipjack and yellowfin tunas appear to be able to increase the minimum observed arterial to venous oxygen content differences approximately 3 times, we predict that they need to increase cardiac output only about 2 times during maximum rates of oxygen uptake. This ratio is not very different from those of other teleosts.
Cardiac scope in amphibians: transition to terrestrial life
Authors: Hillman Stanley S.
Published: August 2008

Systemic oxygen transport essentially limits maximal aerobic capacity in amphibians and consequently may be an important determinant of aerobically supported behaviors. Exercise widens arteriovenous oxygen content difference (5×) and increases heart rate (2×), whereas stroke volume changes very little over resting values. Dehydration is the primary problem facing amphibians in the transition to terrestrial life. Dehydration influences cardiac scope by imposing hyperosmotic, hypovolemic, and hyperviscous stresses on cardiac function. The ability to compensate for hypovolemic stress is the principal adaptation sustaining cardiac scope in more dehydration-tolerant amphibians.
Hematological characterization of goldfish, Carassius auratus L., by image analysis: effects of thermal acclimation and heat shock
Authors: Houston A. H. , Murad A.
Published: August 2008

The morphological characteristics of erythrocyte populations from goldfish, Carassius auratus L., acclimated to constant (15, 25, or 35 °C) and diurnally cycling (25 ± 10 °C) temperature regimes or exposed to abrupt heat shock (15–25 °C, 25–35 °C) were examined by image analysis in an attempt to develop criteria for assessing the stage of development and red cell population age structure. Of the indices considered, nuclear form factor (4π area/perimeter2) appeared to best define the immature state. Estimates of juvenile cell abundances based on nuclear form factor ranged from 23.2 to 56.5% of the cell population and were generally consistent with the thermal histories of the test groups examined. Erythrocyte population characterization is recommended for inclusion in future studies on hematological features of response to altered environmental conditions.
Masked and unmasked pure tone detection thresholds of a harbour seal listening in air
Authors: Terhune J. M.
Published: August 2008

In-air pure tone detection thresholds of a harbour seal (Phoca vitulina) were measured using behavioural psychophysical techniques. Thresholds dropped from about 70 dB re 20 μPa at 0.1 kHz to about 35 dB re 20 μ Pa at 4 kHz and then increased to about 45 dB re 20 μPa at 16 kHz. Increased sensitivities at 2 and 8 kHz, which have been reported in other pinnipeds, were not evident. In-air intensity detection thresholds averaged 32 dB above their underwater counterparts (1–16 kHz). Masking studies found the critical ratios at 0.25, 0.5, and 1 kHz to be 24, 15, and 21 dB, respectively (white noise masker). From 0.2 to 1.5 kHz, bandwidths 20 dB below the level of pure tone maskers were 0.16–0.18 kHz. Circumstantial evidence suggests the possibility that blood vascular changes associated with diving might also influence the sensitivity of the auditory systems of seals. Under optimal conditions, a pup's airborne cries may be detected by its mother at ranges of 1 km or more.
Associations between hydroid species assemblages and substrate types in the mangal at Twin Cays, Belize
Authors: Calder Dale R.
Published: August 2008

Hydroid species composition on various substrates in a mangrove ecosystem was investigated during the winter of 1987 at Twin Cays, Belize, Central America. Soft sediments, on which hydroids were either depauperate (peat) or not observed at all (silt, sand, mud), predominated in the study area. However, firm substrates, including submerged prop roots of red mangrove (Rhizophora mangle), turtle grass (Thalassia testudinum), benthic algae (Chlorophyta and Rhodophyta), floating algae (Turbinaria turbinata and Sargassum fluitans), epibenthic invertebrates (especially sponges, hydroids, molluscs, and crustaceans), wood, and rope, supported a moderately diverse hydroid fauna (48 species). More hydroid species (22) were found on mangrove prop roots than on any other substrate. Six substrate groups and 11 species groups were recognized in numerical analyses of hydroid–substrate frequency data. Constancy of species groups for substrate groups was mostly low or very low, reflecting the low frequency of occurrence of most hydroid species in collections from Twin Cays. Fidelity of some species groups for certain substrate groups was high, especially for those groups occurring on drifting algae and rope. Although most hydroid species were relatively facultative with respect to substrate, bottom type was an important factor influencing their distributions.
A model of egg production by Heterodera schachtii (Nematoda: Heteroderidae)
Authors: Caswell Edward P. , Thomason Ivan J.
Published: August 2008

Egg production by the sugarbeet cyst nematode, Heterodera schachtii, infecting sugarbeet, Beta vulgaris, was assessed at temperatures of 13, 18, 24, and 30 °C in constant-temperature tanks. The minimum-threshold temperature for degree-day accumulation relative to egg production was identified as 8 °C. The relationship between cumulative degree-days (DD) (base 8 °C) and egg production was examined. Egg production began between 160 and 270 DD after hatch and reached a maximum between 390 and 480 DD. Observed egg production (Y) across all temperatures was described as a logistic function of degree-days: Y = 202/(1 + 23726 e−0.034 DD) (r2 = 0.84; P < 0.05). The model depicts initiation of egg production at 140 DD, a maximum average egg production of 202 eggs per female reached at approximately 410 DD, and a maximum rate of egg production of 1.7 eggs/DD reached at approximately 290 DD. The accuracy of the model was limited because observed cumulative egg production was confounded by egg hatch. Accordingly, the cumulative egg production data were adjusted for egg hatch. The adjusted cumulative egg production (Y) was described as a logistic function of cumulative degree-days: Y = 420/(1 + 3319 e−0.023 DD) (r2 = 0.98; P < 0.05). The function depicts egg production initiated at approximately 120 DD. Average maximum egg production is 420 eggs per female occurring at approximately 680 DD, with a maximum egg-production rate of 2.4 eggs/DD occurring at approximately 350 DD.
Alert calls of male Red-winged Blackbirds: call rate and function
Authors: Beletsky L. D.
Published: August 2008

Male Red-winged Blackbirds (Agelaius phoeniceus) give alert calls continuously while on their breeding territories. To investigate the possibility that their rate of calling encodes information about distance to predators or degree of danger associated with different predators, I conducted experiments in which males were presented with stuffed "predators" and human "predators," reflecting varying degrees of danger to the caller, at various distances from their territories. Males called at higher rates when stuffed predators were closer to their territories and increased their rates progressively when a person approached, which supports the hypothesis that information about distance to potential predators is contained in the call rate.