bluuebunny/crossref_metadata_2025 huggingface dataset:
Neighbour–stranger discrimination by song in the veery, a species with song repertoires
Authors: Weary Daniel M. , Lemon Robert E. , Date Elizabeth M.
Published: March 2009

Territorial male veeries (Catharus fuscescens) responded much more to playback of song repertoires from strangers than of those from territorial neighbours. Previous experimental work on species that possess song repertoires has demonstrated only weak neighbour–stranger discrimination. These earlier studies, however, employed only one or two song types, which constituted only a fraction of the repertoires of these species. We used the entire repertoires for playback, these varying from one to three song types. The strong discrimination we demonstrate here is interpreted as evidence that repertoires are not detrimental to recognition by song in veeries. Recordings of song sequences from some individuals consistently evoked a stronger response than did those of others. These differences in response were not related to the number of song types, the number of versions of any one song type, nor to the quality of recording presented.
Use of stable-carbon isotope analysis to estimate marine and terrestrial protein content in gull diets
Authors: Hobson Keith A.
Published: March 2009

Stable-carbon isotope analyses of bone collagen of gulls (Larus spp.) were used to estimate the relative proportion of marine and terrestrial protein in the diets of gulls that are known to use both types of food sources. Mean δ13C values for Glaucous-winged Gulls (n = 23) collected at a Vancouver dump and for Western Gulls (n = 18) from Southeast Farallon Island were −15.0 ± 1.3 and −15.1 ± 0.5‰, respectively. No significant difference in δ13C values was found between adult male and female Western Gulls. Archaeological gull bones (n = 3) show a mean δ13C value of −13.6 ± 1.0‰ and support the assumed marine end point of −13.0‰. The range of terrestrial protein in the diets of coastal gulls was 0–61%. The narrow distribution of δ13C values for Western Gulls from the Southeast Farallon Island colony suggests that gull colonies may be calibrated so that changes in dependence on terrestrial protein can be monitored.
Fourteen years of population fluctuations of Microtus ochrogaster and M. pennsylvanicus in east central Illinois
Authors: Getz Lowell L. , Hofmann Joyce E. , Klatt Brian J. , Verner Louis , Cole F. Russell , Lindroth Richard L.
Published: March 2009

Population densities of Microtus ochrogaster and M. pennsylvanicus were monitored from 1972 to 1986 in three habitats: alfalfa, bluegrass, and tallgrass prairie. Microtus ochrogaster displayed two apparent multiannual population cycles in alfalfa and bluegrass from 1972 to 1976; thereafter only annual (alfalfa) or erratic (bluegrass) fluctuations were apparent. Except for extremely high densities during 1984–1985, population fluctuations of M. ochrogaster in tallgrass were erratically low and there was no evidence of multiannual cycles. During 15 of 29 changes in population density of M. ochrogaster, the amplitude of fluctuations was more than 10-fold; 14 of these changes were preceded by marked population declines or very low densities the previous winter and spring. Microtus pennsylvanicus displayed annual fluctuations in abundance in alfalfa and bluegrass and was erratically high at all times in tallgrass. Only 7 of 32 population fluctuations of M. pennsylvanicus had amplitudes of at least 10-fold; in all 7 cases population density had been high the previous year. We conclude that distinct multiannual population cycles were not characteristic of either species in any habitat over the 14 years. Most previous assumptions of multiannual cycles in these species may be artifacts of short-term studies.
Distribution and haul-out behavior of harbor seals in Glacier Bay, Alaska
Authors: Calambokidis John , Taylor Barbara L. , Carter Susanne D. , Steiger Gretchen H. , Dawson Pierre K. , Antrim Liam D.
Published: March 2009

Over 5000 harbor seals haul out on icebergs calved from tidewater glaciers in Muir and Johns Hopkins inlets in Glacier Bay, Alaska. During June, these sites are used primarily by parous females and pups, and in August, by molting seals. The number of mothers and pups was higher than expected for the total number of seals in Glacier Bay, indicating an immigration of some parturient females from outside Glacier Bay. The number of seals counted varied throughout the day with greatest numbers around midday. In Muir Inlet the number of seals hauled out was positively correlated with percent ice cover. Ice that is suitable for hauling out may presently limit the abundance of seals in this area. The retreat of Muir Glacier has dramatically reduced the ice available to seals and, if it continues, will likely result in the elimination of drift-ice habitat in the near future. Seals from both inside and outside Glacier Bay apparently use ice habitat in Muir and Johns Hopkins inlets when giving birth, when nursing pups, and when moulting for protection from terrestrial and marine predators, and because it is relatively abundant and easily accessible at all tides and times.
The blood leukocytes of Bufo marinus: a light, phase-contrast, and histochemical study
Authors: Cannon M. Samuel , Sampson H. W. , Kapes E. D.
Published: March 2009

Blood leukocytes of Bufo marinus were studied by light and phase-contrast microscopy and histochemical techniques for the localization of glycogen, lipids, several basic proteins, and a number of hydrolytic and oxidative enzymes. The hydrolytic enzymes occurred in varying amounts in neutrophils, eosinophils, lymphocytes, and monocytes; neutrophils were the only leukocytes to demonstrate alkaline phosphatase activity, while β-glucuronidase was only seen in lymphocytes, and aryl-sulfatase was not observed in any leukocytes. Periodic acid – Schiff (PAS) positive granules also occurred in varying amounts in leukocytes. Slight lipid activity was only seen in neutrophils, while arginine, and (or) lysine, and tyrosine reactivity was only observed in eosinophils. The appearance and histochemical reactivity of acid phosphatase granules in neutrophils corresponded closely with the appearance and number of specific neutrophilic granules seen in Wright–Giemsa preparations and with the PAS-positive granules. Small lymphocytes were myeloperoxidase (peroxidase) negative; β-glucuronidase, acid phosphatase, and PAS-positive granules corresponded to neutral red granules seen in supravital films. The oxidative enzymes also occurred in differing amounts in leukocytes, but strongly suggested that the leukocytes of Bufo marinus are capable of some degree of aerobic and anaerobic metabolism.
Role of male and female Ring-billed Gulls in the care of young and territorial defense
Authors: Dulude Anne-Marie , Baron Georg , McNeil Raymond
Published: March 2009

This study deals with differences between the sexes in the parental and territorial behaviour of 17 pairs of Ring-billed Gulls (Larus delawarensis) breeding in the periphery of a colony on Île de la Couvée, Quebec. Males devoted more time than females in territorial attendance, but there was no difference between the sexes in the frequency of feeding the young. Territorial attendance progressively decreased from the end of the 1st week of June and was lower after hatching than before. Males were chiefly involved in high-level agonistic interactions. Agonistic interactions on the whole were more frequent during the post-hatch period; this increase appeared to be related to the greater mobility of the young and to the fact that they attempted to rob regurgitations.
Experimental analysis of predation on the diel vertical migrations of a larval salamander
Authors: Stangel Peter W. , Semlitsch Raymond D.
Published: March 2009

The effects of a predatory fish on diel vertical migrations of aquatic larvae of the salamander Ambystoma talpoideum were tested in artificial ponds. Associations between larval activity and water temperature and resource abundance were also examined. In the absence of fish, larval activity was associated with the onset of darkness and decreasing water temperature. Peak larval activity occurred at 2130, about 3.5 h after peak summer water temperatures. Resource abundance (zooplankton density) in the water column did not differ from day to night. Larvae were more active during the day in spring than in summer. The presence of a visually orienting fish predator restricted larval activity to the benthic layer. Our results suggest that the presence of a visually orienting predator can be a major factor affecting patterns of diel vertical migrations. Daily and seasonal changes in water temperatures may affect thermoregulatory behavior, thereby influencing diel vertical migration patterns.
Diet of house wrens (Troglodytes aedon) and the abundance of the invertebrate prey in the dune-ridge forest, Delta Marsh, Manitoba
Authors: Guinan Daniel M. , Sealy Spencer G.
Published: March 2009

The diet of house wrens (Troglodytes aedon) was determined from gut contents of wrens collected on the forested dune ridge, Delta Marsh, Manitoba, in 1981 and 1982. Despite a preponderance of midges (Diptera: Chironomidae) in the food resources that were available to the wrens, the wrens consumed representatives of most of the invertebrate taxa that were sampled by sweep netting in the feeding habitat. The ranked importance of 13 taxa in the wren diet was correlated most closely with the ranks of their biomass available. When larger individuals within a taxa were available they were consumed in greater proportion by wrens. Chironomids were an exception; small individuals were usually eaten in greater proportion than expected from their abundance in sweep-net samples. The percentage of small chironomids eaten, however, decreased as their abundance increased. Prey selection apparently depended on abundance, size, and ease of capture. House wrens apparently were less selective when suitable prey were abundant.
Ecological relationships between Common Murres, Uria aalge, and Thick-billed Murres, Uria lomvia, at the Gannet Islands, Labrador. I. Morphometrics and timing of breeding
Authors: Birkhead T. R. , Nettleship D. N.
Published: March 2009

Several aspects of the breeding biology of Common Murres (Uria aalge) and Thick-billed Murres (Uria lomvia) in 1981–1983, at the Gannet Islands, Labrador, are described. At this colony there were ca. 60 000 pairs of Common Murres, and 1400 pairs of Thick-billed Murres. Common Murres were slightly heavier and had significantly shorter wings, and longer, narrower bills than Thick-billed Murres. The timing of egg laying varied between years (late breeding in one year was associated with late ice breakup), but the median laying date of Common Murres was consistently earlier (by up to 10 days) than that of Thick-billed Murres. For both species median laying dates fell between mid and late June each year. Common Murre eggs were larger and relatively longer than Thick-billed Murre eggs, but in both species fresh egg weight was about 11% of adult body weight. Incubation periods were similar in each species (33 days), but chick-rearing periods were longer in Common Murres (24 days) than in Thick-billed Murres (21 days) in all years. Seasonal patterns of colony attendance were broadly similar in the two species each year, except that Common Murres showed a consistent increase in numbers between laying and chick departure, and tended to remain at the colony for less time after chicks had departed compared with Thick-billed Murres. All birds of both species left the colony by mid-September each year.
Seasonal changes in prevalence and intensity of Cosmocercoides dukae (Nematoda: Cosmocercoidea) in Deroceras laeve (Mollusca)
Authors: Vanderburgh Daryl J. , Anderson R. C.
Published: March 2009

A natural population of Deroceras laeve was examined regularly for the presence of Cosmocercoides dukae (Holl, 1928) Travassos, 1931. Transmission of C. dukae in D. laeve occurred in late spring and early summer before adult slugs from the previous year died in July. Transmission to juvenile slugs (hatched from eggs laid in spring) continued in late summer and fall. Histological sections of slugs exposed experimentally to larvae of C. dukae revealed that larvae penetrate slug tissues. Arion fasciatus, Arion hortensis, and Zonitoides nitidus represent new host records for C. dukae.
Phyllodistomum umblae (Fabricius) (Digenea, Gorgoderidae) from British Columbia salmonids: a description based on light and scanning electron microscopy
Authors: Bakke T. A. , Bailey R. E.
Published: March 2009

Specimens of Phyllodistomum umblae (Fabricius, 1780) from Oncorhynchus nerka (Walbaum) from the Nautley River, British Columbia, and Salmo gairdneri Richardson from the Stuart River, British Columbia, are described and figured using light microscopy and scanning electron microscopy. Particular emphasis is placed on describing the numbers, types, and arrangement of papillae as seen with scanning electron microscopy. No significant differences were observed between the present Canadian material from O. nerka and S. gairdneri and specimens of P. umblae described from Norway, Sweden, and the U.S.S.R. Thus, P. umblae has a holarctic distribution in salmonids. Phyllodistomum limnosa Sandeman and Pippy, 1967, described from Salmo salar L. and Salvelinus fontinalis (Mitchill) from Newfoundland, is regarded as a synonym of P. umblae. Phyllodistomum lachancei Choquztte, 1947, described from S. fontinalis in Quebec, probably is also a synonym of P. umblae, but a more detailed scanning electron microscope study of the papillae in P. lachancei is required for confirmation.
Developmental stability and heterozygosity in chum (Oncorhynchus keta) and pink (Oncorhynchus gorbuscha) salmon
Authors: Beacham T. D. , Withler R. E.
Published: March 2009

We compared developmental stability as measured by fluctuating asymmetry within individual adults for gill raker and branchiostegal ray number and pectoral and pelvic fin length for three populations of chum salmon (Oncorhynchus keta) and one of pink salmon (Oncorhynchus gorbuscha). There was no association between individual heterozygosity calculated at 10 electrophoretic loci for chum salmon and 13 loci for pink salmon and magnitude of fluctuating asymmetry for the four morphological characters examined. More heterozygous individuals were not less asymmetrical, and thus our results provide no evidence to suggest that increased heterozygosity results in an increased canalization of morphology during development and growth.
Sex and aggregation attractants of Heligmosomoides polygyrus (Nematoda: Trichostrongylidae)
Authors: Riga Ekaterini , MacKinnon Barbara M.
Published: March 2009

Chemical communication in the mouse nematode Heligmosomoides polygyrus was examined in vitro. Virgin males were significantly attracted to virgin females, moving an average of 2.43 cm/h with a maximum of 60% of the males reaching target females. Female worms were moderately attracted to target males; 20% of the responding worms reached the target at an average speed of 1.07 cm/h. In the homosexual trials, 20% of responding females reached target females with an average speed of 1.70 cm/h. Homosexual experiments among males showed a slight attraction. Responding worms moved at an average speed of 0.84 cm/h but none of the migrating males reached the target. Control experiments using no attractant showed that responding worms, in the absence of any target, travelled randomly. Controls using worm products and homogenized worms showed that males reached the female incubant with an average speed of 1.17 cm/h. Experiments using more than one responding male indicated that males may inhibit the movement of other males toward the target females. There appear to be both aggregation and sex attractants in H. polygyrus as well as inhibitory chemicals produced by males which influence other nearby males.
Phylogenetic analysis and revision of Kroeyerina Wilson, 1932 (Siphonostomatoida: Kroyeriidae), copepods parasitic on chondrichthyans, with descriptions of four new species and the erection of a new genus, Prokroyeria
Authors: Deets Gregory B.
Published: March 2009

Four new species of Kroeyerina Wilson, 1932, are described and redescriptions of the previously known species are given. Phylogenetic analysis of the genus Kroeyerina produces a cladogram that indicates that Kroeyerina meridionalis Ramirez, 1975 warrants its own generic status. The genus Prokroyeria is established to accommodate K. meridionalis, the only member of the Kroyeriidae Kabata, 1979 that infests holocephalan branchial lamellae. Higher level (more inclusive) analysis of the genera within the family further corroborates this systematic restructuring. The hierarchical relationships of the species constituting Kroeyerina and the intrafamilial relationships of the genera within Kroyeriidae are congruent with some of the recently proposed patterns of their chondrichthyan hosts' evolution.
Notes on the taxonomy of West African gecarcinucids of the genus Globonautes Bott, 1959 (Decapoda, Brachyura)
Authors: Cumberlidge Neil
Published: March 2009

Globonautes leonensis n.sp. is described from three specimens from Sierra Leone, in the unnamed collection of the British Museum (Natural History), London. Globonautes monodosus Bott, 1959 is revived and redescribed from the holotype from Guinea. The gonopods of the holotype of Globonautes macropus (Rathbun, 1898) from Liberia (the type species of the genus Globonautes Bott, 1959) prove to be different from accounts in the literature, and throw into question the identity of Bott's species. The genus Globonautes is redefined, and a new key to distinguish between the species of the genus is provided.
The effect of temperature and photoperiod on the induction of larval diapause in the mosquito Aedes togoi (Theobald) (Diptera: Culicidae)
Authors: Galka Brian E. , Brust Reinhart A.
Published: March 2009

Aedes togoi (Theobald) from Vancouver, B.C., may enter diapause in either the egg or larval stage. Larval diapause occurred in the fourth instar, when immatures were maintained at 16 °C or less, at photoperiods shorter than 12 h light/day. The critical photoperiod was calculated as 10.9L:13.1D at 16 °C. Larvae that failed to pupate after 40 days following hatching were recorded as being in diapause. At light periods greater than 12 h at 16 °C, there was no larval diapause and, at 14 °C, 100% of the larvae diapaused at 10L:14D. Temperatures of 18 °C or higher, at 10L:14D, prevented larval diapause.
The effect of temperature and photoperiod on the induction of embryonic diapause in the mosquito Aedes togoi (Theobald) (Diptera: Culicidae)
Authors: Galka Brian E. , Brust Reinhart A.
Published: March 2009

Aedes togoi (Theobald) from Vancouver, B.C., enters embryonic diapause when immatures, adults, and eggs are maintained at temperatures ranging from 22 to 28 °C, at photoperiods shorter than 15 h light/day. There was little to no embryonic diapause when the population was maintained at 24 °C and 17L:7D. The critical photoperiod was 14.4L:9.6D at 22 °C. A decrease in the frequency of diapause was observed as (i) temperature of the pupae, adults, and eggs increased from 18 to 28 °C when larvae were maintained at 24 °C 17L:7D; (ii) temperature of the egg stage increased from 15 to 30 °C, at 10L:14D, and stages preceding the egg stage were maintained at 24 °C 17L:7D; (iii) stages preceding the egg stage were maintained at 24 °C 17L:7D and the photoperiod was increased from 10L:14D to 18L:6D; (iv) temperature of the egg stage increased from 18 to 25 °C, at 10L:14D, and stages preceding the egg stage were maintained at 24 °C 17L:7D.
Effects of fish on feeding and growth of larval Ischnura verticalis (Coenagrionidae: Odonata)
Authors: Dixon Susan M. , Baker Robert L.
Published: March 2009

We used laboratory studies to investigate how fish affected a larval zygopteran's activity, ability to locate a food patch, and growth. Larval Ischnura verticalis spent less time at food patches in the presence of fish (Lepomis gibbosus) when food patches were permanent, but when food patches were ephemeral, fish did not have a significant effect. In addition, fish had no effect on larval feeding on mobile prey (Daphnia magna), nor did fish have any effect on growth of larvae supplied with ephemeral prey patches.
Revision and phylogenetic analysis of the Gyrocotylidea Poche, 1926 (Platyhelminthes: Cercomeria: Cercomeromorpha)
Authors: Bandoni Susan M. , Brooks Daniel R.
Published: March 2009

Phylogenetic analysis of 10 gyrocotylidean platyhelminth species, based on 24 character states comprising 13 homologous series, produced two similar phylogenetic trees of equal length. The consistency index value for each tree is 87.5%, indicating a low degree of parallel evolution in the morphology of gyrocotylidean platyhelminths. Slightly more than half of the observed associations between gyrocotylideans and holocephalan hosts can be attributed to coevolution. Remaining associations must be attributed to colonization, but these represent recolonizations of plesiomorphic hosts. The geographic distribution of gyrocotylideans remains enigmatic, as part of it seems to predate tectonic plate movements. Extensive dispersal has occurred; dispersal events are correlated with host transfers. It is hypothesized that the origin of gyrocotylideans predates separation of the continents, and that there were two phases in the evolution of the gyrocotylideans, an initial phase of coevolution and a later phase of colonization and dispersal.
Recurrent groups of zooplankton in the Bay of Fundy and southwest Nova Scotia regions, Canada
Authors: Corey S. , Milne W. R.
Published: March 2009

Recurrent group analysis of the Bay of Fundy and southwest Nova Scotia regions on 40 species of zooplankton were compared on a seasonal and annual basis. One major recurrent group occurred per region. Six and five core species occurred in the Bay of Fundy and southwest Nova Scotian waters, respectively. Of these core species, Sagitta elegans, Calanus finmarchicus, and Metridia lucens were common to both areas. The interconnection of the Bay of Fundy and southwest Nova Scotia zooplankton communities is relatively strong (75% of core species for either area occurred in the other area in three of the four surveys). All core species were endemic and boreal.
An investigation of host influence on soluble protein banding profiles of Hymenolepis spp. (Cestoidea), using isoelectric focusing
Authors: Dixon Brent R. , Arai Hisao P.
Published: March 2009

Protein separation techniques have been utilized in recent years as alternative means of differentiating species and strains of tapeworms. As with the traditional morphological approach, however, there is the potential for host influence. For such separative techniques to be useful taxonomically it is important that the banding profiles differentiating parasites be consistent, regardless of host species. To test for host influence, two Hymenolepis species were maintained both in preferred and alternative definitive host species. The soluble proteins of tapeworms of a given species, from the different host species, were then subjected to isoelectric focusing, and the resulting banding patterns were compared. There were no noticeable differences in the banding profiles of these worms, indicating a lack of host influence. If these findings hold for other tapeworm genera, isoelectric focusing of soluble proteins could have practical value in parasite surveys.
Activity budgets and movement rates of caribou encountering pipelines, roads, and traffic in northern Alaska
Authors: Murphy Stephen M. , Curatolo James A.
Published: March 2009

Insect harassment significantly affected caribou behavior by decreasing time spent feeding and lying and by increasing locomotion. Effects of oilfield disturbance on behavior were most pronounced when insects were absent, suggesting that disturbance and insects did not have a substantial additive effect on behavior. When insects were absent, caribou within 600 m of an elevated pipeline and road with traffic, and within 300 m of a pipeline and road without traffic, had significantly different activity budgets than undisturbed caribou; disturbance effects were significantly greater in the site with traffic. Time spent lying and running and movement rates were the best indicators of oilfield disturbance, whereas time spent feeding was not affected. Cow–calf-dominated groups and groups larger than 10 animals reacted to lower levels of disturbance than other group types, but all group types reacted similarly to high levels of disturbance. Separation of elevated pipelines from heavily traveled roads is recommended as a means of minimizing disruption of caribou behavior and movements. Energetic stress resulting from disturbance-induced changes in behavior should be minimal in a properly designed oilfield.
A phylogenetic study of the Lutrinae (Carnivora; Mustelidae) using morphological data
Authors: Jong C. G. van Zyll de
Published: March 2009

The phylogenetic relationship of the 13 extant species of otters were analyzed by canonical variate analysis using mensural data and by Wagner analysis using qualitative characters. The results of the two analyses showed a high degree of concordance. The information of the generalized distance (D) and Wagner trees was combined in an Adams-2 consensus tree. The phylogenetic hypothesis generated deviates from currently accepted classifications chiefly in separating the species of river otters of the genus Lutra, as it is generally conceived, into two groups of genera. One, the New World river otters (Lontra), is a monophyletic group phylogenetically linked to the African and Asian clawless otters (Aonyx and Amblonyx). The other group, their Old World ecological counterparts (Lutra), constitutes a different clade. Enhydra and Pteronura are the most divergent of living otters, the former being closer to the clawless otters and the latter to the smooth-coated otter (Lutrogale), which in turn is phylogenetically close to the Old World river otters (Lutra). Available independent evidence, although incomplete, does not contradict the hypothesis.
Structural and functional composition of the community of Chironomidae (Diptera) in a Canadian Shield stream
Authors: Rempel R. S. , Harrison A. D.
Published: March 2009

The chironomid community of Canisbay Creek, a Shield region stream flowing in Algonquin Park, Ontario, revealed substantial differences in species structure and emergence phenology to that previously described for the community of a spring-fed wooded stream in southern Ontario. These differences are attributed to the different chemical and thermal regimes in the two streams. Weekly samples were taken from anchored floating emergence traps. Of the 72 species found, 15 are undescribed. Most were either Orthocladiinae or Tanytarsini; no Diamesinae were recorded. Both univoltine and multivoltine species occurred and some of the latter became asynchronous during spring and summer. Absolute temperatures and daily thermal divergence played important parts in emergence cueing. The Chironomidae are shown to be active components in the ecosystem throughout the year, and it is argued that the season of larval growth, along with relative body size, should be considered in the functional classification of the species in this group.
Production of sexual and asexual morphs and changes in reproductive sequence associated with photoperiod in the pea aphid, Acyrthosiphon pisum (Harris)
Authors: MacKay P. A.
Published: March 2009

Production of sexual and asexual morphs of a clone of the pea aphid, Acyrthosiphon pisum (Harris), was monitored under photoperiods ranging from 18L:6D to 10L:14D at 20 °C. Under long photophases only viviparae were produced. At intermediate photophases families were produced in which the oldest progeny were females while the youngest progeny were males. A 1- to 2-day pause intervened between the production of these two groups. Females were produced only for 3–4 days while males were produced for about 12 days. At longer intermediate photophases the females were viviparae while at shorter intermediate photophases they were oviparae. In families containing both female morphs, viviparae were born first. At the shortest photophases, families consisted entirely of females, oviparae being produced in the first half and viviparae in the second half of the reproductive period. The ecological significance of these sequences is discussed.
The formation of diapause aggregations by larvae of Neophylax fuscus Banks (Trichoptera: Limnephilidae) and their influence on mortality and development
Authors: Martin Ian D. , Barton David R.
Published: March 2009

Fifth-instar larvae of the caddisfly Neophylax fuscus Banks (Trichoptera: Limnephilidae) enter a 4-month diapause in April after aggregating on the undersides of stream rocks in gravel cases. Aggregations have up to several hundred members, and densities within aggregations range from 1000 to 17 263 cases/m2. Field experiments conducted between 1984 and 1986 showed that larvae preferred to settle where initial larvae had already attached, but that there was no evidence for a chemical cue for aggregation. Mortality during the diapause but before pupation averaged 37.9%. Both exposure to low water and high density within aggregations contributed to increased mortality. Parasitism and predation appeared to be rare. The developmental synchrony of pupae and emergence synchrony were related to aggregation density during diapause. Low density aggregations tended to have low synchrony of development and emergence, while high density aggregations had higher synchrony.
The fine structure of home ranges of male Chelydra serpentina: are snapping turtles territorial?
Authors: Galbraith David A. , Chandler Mark W. , Brooks Ronald J.
Published: March 2009

Four male snapping turtles (Chelydra serpentina) were located by radiotelemetry during the summers of 1985 and 1986 in 5.5-ha Broadwing Lake, Algonquin Park, Ontario. We measured sizes and overlaps of home ranges and core areas. Average size of home range did not differ greatly between years, and location of individual home ranges remained stable from one year to the next in two of three turtles studied both years. Within individual home ranges, the distribution of locations of most turtles was aggregated, but was not significantly different from Poisson distributions. Home ranges overlapped, but the proportion of areas used intensively by individuals was not different in overlapping and nonoverlapping areas, indicating that the areas of intensive use were not exclusive. However, the turtles spaced themselves farther apart than expected from the geometry of the home ranges, possibly the result of intraspecific aggression. If territory is defined as a fixed, exclusive, defended area, then male snapping turtles are not territorial during the summer, but occupy relatively stable home ranges which overlap, and whose spacing may in part be determined by aggressive interactions.
The development of chinook (Oncorhynchus tshawytscha) and chum salmon (Onchorhynchus keta) embryos and alevins under varying temperature regimes
Authors: Murray C. B. , Beacham T. D.
Published: March 2009

Chinook (Oncorhynchus tshawytscha) and chum salmon (O. keta) embryos were initially incubated at 4, 8, or 12 °C and then maintained at the same temperature or systematically transferred at completion of epiboly (early transfer) or complete eye pigmentation (late transfer) to each of the other incubation temperatures. For both species initial incubation at 8 or 12 °C resulted in higher embryo and alevin survival rates than initial incubation at 4 °C. Increasing or decreasing temperature regimes had little effect on embryo and alevin survival rates. Transfers after epiboly or completion of eye pigmentation had little influence on subsequent survival rates, except the early and late transfers of chinook salmon embryos from 4 to 12 °C, which resulted in an increase in alevin mortality. Hatching and emergence times varied inversely with temperature, and chum salmon generally hatched and emerged sooner than chinook salmon. Decreasing temperature regimes produced longer and heavier chinook salmon alevins and fry, but constant incubation at 8 °C or early or later transfers to 8 °C resulted in longer and heavier chum salmon alevins and fry. Temperature regimes that simulate those experienced by a species during natural incubation tend to enhance survival and alevin and fry size. Different trends in embryo and alevin developmental characters between species and among families within a species were assumed to reflect adaptations to variable natural incubation conditions.
The effect of ingested benzoylphenylurea on the ultrastructure of the cuticle deposited during the last larval instar of Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae)
Authors: Percy-Cunningham Jean , Nicholson Diane , Retnakaran Arthur
Published: March 2009

The sequential ultrastructural changes induced by the ingestion of a sublethal dose of a benzoylphenylurea, chlorfluazuron, were investigated in sixth-instar larvae of the spruce budworm, Choristoneura fumiferana. The 4-day-old, postecdysis larvae showed the most profound ultrastructural effects. The newly formed endocuticle showed an absence of lamellae, indicating the lack of formation of chitin microfibrils. Vacuolated and fibrous areas containing an amorphous material, possibly proteinaceous, were observed in the region where lamellae would normally be present. The epidermal cells had microvilli with swollen and rounded tips. These cells also contained oval vesicles containing granular amorphous material. The in vivo inhibition of chitin deposition by this benzoylphenylurea was readily apparent. It is suggested that the amorphous material observed in the zone where chitin was lacking is the protein component of the glycoprotein chitin. It is possible that the benzoylphenylurea inhibits the assembly of the amino sugar with the protein to form microfibrils.
Temporal and age-related variation in the laying rate of the parasitic brown-headed cowbird in the eastern Sierra Nevada, California
Authors: Fleischer Robert C. , Smyth Adrianna P. , Rothstein Stephen I.
Published: March 2009

Spatial, temporal, and age-related variation in the laying rate of female brown-headed cowbirds in Mono Co., California was assessed by determining the proportions of samples of live-trapped females that had an oviducal egg. Females were considered to have an oviducal egg if their abdomens felt distended. The technique was tested for reliability by predicting the laying condition of 36 females and then holding them overnight to obtain eggs the following morning. The predictions were upheld for 92% of the cases. The highest laying rates for the 1982 and 1984 seasons were 0.79 and 0.77 eggs per day, respectively. During the middle part of the 1984 breeding season (22 May – 18 June) laying rates averaged 0.64 ± 0.12 eggs per day. A seasonal average of 30.5 eggs per female was calculated from the daily laying rates. Results from 1982 began in mid-season, but showed that laying rates were higher late in the season and declined more rapidly than in the 1984 season. A total of 75 examinations of 54 females of known age during 1984 revealed that the laying rates of yearling females were significantly lower than those of adults. Dividing these samples into three time periods revealed that the reduced laying rate is caused by a delay in the initiation of reproduction by yearlings. Results suggest that the delay may be due to a later arrival date of yearlings onto the summer range.
Behavioural responses of lake charr (Salvelinus namaycush) embryos to simulated acidic runoff conditions
Authors: Gunn J. M. , Noakes D. L. G. , Westlake G. F.
Published: March 2009

Lake charr (Salvelinus namaycush) embryos in the later stages of yolk absorption avoided water with pH < 6.0. The addition of inorganic Al (≤ 200 μg∙L−1) did not increase the avoidance response to low pH. Embryos tested just after hatch had little swimming ability and showed no avoidance to acutely lethal H+ (pH 4.0). In vertical substrate-filled tanks that simulated conditions at natural spawning sites, there were no significant effects on embryo survival, or movement within the substrate from pulse exposure (8 h) to low pH (4.5) and elevated Al (100, 200, 500 μg∙L−1). Preference for contact with the substrate appeared to override the avoidance reactions observed in horizontal counter-current tanks. Thigmotaxis, combined with poor swimming ability of embryos, appears to eliminate the possibility that lake charr embryos will effectively avoid the acidic runoff water that enters the rubble of spawning sites during snowmelt.
The potential of parasitism in the structuring of a salt marsh stickleback community
Authors: Poulin Robert , FitzGerald Gérard J.
Published: March 2009

To determine if ectoparasites have the potential to play a role in structuring a salt marsh stickleback community, we measured abundance of the copepod Thersitina gasterostei and fish louse Argulus canadensis in the field, and quantified their effects on the condition and survival of juvenile fish. We also determined if differential host selection occurred among three sympatric host species of sticklebacks, Gasterosteus aculeatus, Gasterosteus wheatlandi, and Pungitius pungitius. The abundance of T. gasterostei was highest from September to November. They were overdispersed on their hosts, so that only a few fish harboured large numbers of parasites. Prevalence and intensity of T. gasterostei were higher on P. pungitius and G. aculeatus than on G. wheatlandi. There was no evidence that larger fish harboured more T. gasterostei than smaller fish. Abundance of A. canadensis peaked in August. Heavy loads of A. canadensis decreased the survival of G. aculeatus and G. wheatlandi in aquaria. In laboratory experiments, P. pungitius acquired more A. canadensis, followed by G. wheatlandi and G. aculeatus, respectively. Argulus canadensis had a greater attack success and faced less risk on P. pungitius, while its attack success was lowest and risk highest on G. aculeatus, with values for G. wheatlandi being intermediate. Host size and presence of T. gasterostei on hosts had no influence on host selection by A. canadensis. An increase in host density resulted in a decrease in the mean number of A. canadensis per fish. We suggest that parasitism could play a role in structuring this stickleback community through its differential effects on the three host populations.
Population, productivity and DDT contamination trends of Northern Gannets (Sula bassanus) at Bonaventure Island, Quebec, 1967–1984
Authors: Chapdelaine G. , Laporte P. , Nettleship D. N.
Published: March 2009

A comparison of the results of recent surveys of Northern Gannets on Bonaventure Island shows that the population increased from 16 400 pairs in 1976 to 21 100 pairs in 1984, which represents an annual increase of 3.2%. Hatching success was only 36–40% between 1966 and 1970, after which it increased to 58% in 1974 and then varied from 78 to 89% during 1976–1984. Net productivity now exceeds the level necessary to maintain zero population growth. The marked increase in breeding performance coincided with a significant decline in DDT and dieldrin residues in eggs, which suggests that toxic chemical contamination was responsible for the low hatching success between 1966 and 1970.
Temperature dependence of in vitro androgen production in testes from hibernating ground squirrels, Spermophilus lateralis
Authors: Barnes Brian M. , Licht Paul , Zucker Irving
Published: March 2009

The effect of temperature on the in vitro androgen secretion of testes from hibernating ground squirrels was measured in response to stimulation by luteinizing hormone (LH). We wished to determine whether hibernating ground squirrels can maintain responsiveness of gonads while at the low body temperatures of torpor. In gonads incubated at 32 °C, secretion of testosterone increased in a dose-dependent manner in response to ovine-LH or ground squirrel pituitary homogenate. This responsiveness was reduced at 20 and 9 °C and absent at 5 °C, the temperature that most closely approximates the body temperature of torpid ground squirrels. This temperature sensitivity was similar to that in the nonhibernating laboratory mouse. Superfusion of ground squirrel testes revealed a lag of testosterone secretion in response to LH and, additionally, an ability of testes to secrete testosterone after being only briefly exposed to ovine-LH while at 5 °C. These results provide evidence against a hypothesis of temperature compensation that would allow continued testis function during torpor, and support a previous study which indicated that gonadal growth is restricted to intervals of normothermy during and after the hibernation season.
Island biogeography of vertebrates in Georgian Bay Islands National Park
Authors: Schmiegelow Fiona K. A. , Nudds Thomas D.
Published: March 2009

Terrestrial vertebrates on 28 of 77 islands in Georgian Bay Islands National Park were examined by taxon (i.e., nonvolant mammals, herptiles, and birds) to determine whether the number of species on each island was affected by variation in dispersal capability and susceptibility to extinction, as predicted by the equilibrium theory of island biogeography. About 70% of the variation in number of species on islands was accounted for by the area of the islands. Species (S) – area (A) relationships (S = cAz) for birds, herptiles, and nonvolant mammals all differed significantly in slope and intercept (P < 0.05). Intertaxa comparisons revealed that birds exhibited the greatest numbers of species on all sizes of islands and smallest slope (z = 0.32); herptiles exhibited intermediate numbers of species on all sizes of islands and intermediate slope (z = 0.37). Of all taxa, nonvolant mammals exhibited the lowest numbers of species on all sizes of islands and greatest slope (z = 0.42), consistent with the predictions of the theory. These results reinforce earlier suggestions that designs for nature reserves should accommodate intertaxa variation in dispersal ability and susceptibility to extinction.
Mechanisms and properties of sodium transport in locust rectum
Authors: Black K. , Meredith J. , Thomson B. , Phillips J. , Dietz T.
Published: March 2009

Steady-state fluxes of 22Na+ were measured as a function of external Na+ concentration across locust recta mounted as flat sheets under short-circuit conditions. A net flux [Formula: see text] at all concentrations confirmed that absorption was an active process obeying Michaelis–Menten kinetics with Kt of 17 mM and Vmax of 1.5 to 2.5 μequiv. cm−2 h−1. [Formula: see text] was not affected by cAMP, was independent of external Cl− levels and stimulated short-circuit current (i.e., Cl− transport), and was partially inhibited by amiloride and ouabain but not by vanadate. Using intracellular electrodes, a small Na+ conductance that was not due to cotransport with organic substrates was identified in the apical plasma membrane. A semiquantitative model for Na+ absorption in this epithelium is proposed. We surveyed the locust neurosecretory system for water-soluble factors that might control rectal Na+ reabsorption.
The ultrastructure and systematics of Schizocaryum dogieli, a ciliate endocommensal in Pacific echinoids
Authors: Lynn Denis H. , Frombach Sandra
Published: March 2009

Schizocaryum dogieli Poljansky &Golikova, 1957 was isolated from several species of Pacific strongylocentrotid echinoids in the area of Friday Harbor, WA. The somatic kineties are composed of polykinetids of up to 15 kinetosomes of which only the right posterior one bears a postciliary ribbon at triplet 9, an anteriorly directed kinetodesmal fibril at triplets 6 and 7, and a transverse ribbon at triplets 4 and 5. The other kinetosomes are irregularly associated with this kinetosome by dense basal connectives. The oral ciliature consists of a series of primary transverse rows separated by cortical ridges and associated with numbers of irregularly arrayed, ciliated kinetosomes. The rightmost kinetosome of each primary transverse row apparently bears a postciliary ribbon. Schizocaryum dogieli is removed from the family Plagiopylidae and placed in a new, monotypic family, the Schizocaryidae Jankowski n.fam. This family has an uncertain position within the phylum Ciliophora.
A contribution to the taxonomy of the aquatic Oligochaeta (Haplotaxidae, Phreodrilidae, Tubificidae) of South America
Authors: Brinkhurst R. O. , Marchese M.
Published: March 2009

Fourteen taxa in three families are noted from regions of South America. Monopylephorus moleti (Tubificidae) and Haplotaxis aedeochaeta (Haplotaxidae) are new to science, while Potamothrix bavaricus (Tubificidae) and Phreodrilus lacustris (Phreodrilidae) are new records for the continent. The tubificids Isochaetides lacustris, Epirodrilus antipodum, and Paranadrilus descolei are redescribed. The report for Rhyacodrilus palustris from South Georgia is shown to be erroneous and should refer to Rhyacodrilus coccineus. The list of known species from the area is reviewed and some anatomical features of Haplotaxis species from Europe and North America are noted.
Man as a breath-hold diver
Authors: Hong Suk Ki
Published: March 2009

There are many thousands of both recreational and professional divers daily engaged in breath-hold diving throughout the world. The most widely known breath-hold divers are found among males and females in Japan and Korea, collectively called the ama. However, compared with many diving animals, man's ability as a breath-hold diver is very much limited. The average duration of a dive is 30–60 s, although one can dive for a period of up to 2–3 min. Usual depths of dive are 5–20 m. However, Jacques Mayol dove to 105 m in 1983, setting a new world record. It is still not clearly understood how one can reach such a depth without developing a pulmonary "squeeze." Human divers also display a mild but significant diving bradycardia which is often accompanied by cardiac arrhythmias. Although the cardiac output decreases slightly, the arterial blood pressure increases during breath holding. It has been suggested, but not unequivocally demonstrated that these cardiovascular changes observed during diving in man subserve to conserve O2 as in diving animals. Human divers descend to the bottom while retaining a considerable amount of air in the lung, thus allowing diffusion of N2 into the blood. As a result, human breath-hold divers can develop decompression sickness if they dive to deeper depths frequently enough. The major limiting factor for human divers is the loss of body heat to the surrounding medium (water) which has a high thermoconductivity. The subcutaneous fat thickness of human divers is much less than that in diving animals and thus human divers are at a great disadvantage. Although repetitive exposures to cold water stress are known to induce a significant cold acclimatization in man, these changes are rather ineffective in prolonging cold water diving time.
Raiding shoal size and a distraction display in male sticklebacks (Gasterosteus)
Authors: Ridgway Mark S. , McPhail J. D.
Published: March 2009

In threespine sticklebacks (Gasterosteus aculeatus), shoals of foraging conspecifics attack the nests of parental males and consume the offspring. This type of nest predation also occurs in lakes with sympatric species pairs of sticklebacks (Gasterosteus sp.) in which benthic stickleback shoals attack the nests of parental limnetic males. We manipulated shoal size of benthic sticklebacks in Paxton and Enos lakes to determine if there is a minimum shoal size necessary before parental limnetic males will perform the spasmodic swim display, a behaviour used by parental males to lure foraging shoals away from their nest and offspring. Males showed a significant increase in display frequency beginning with shoals of eight fish. The display occurred only when there were offspring in the nest and not when the nest was empty. We interpret the display to be a foraging deception in which parental males manipulate raiding shoals into giving up their search for a food source, causing them to leave the area of the male's nest site. This distraction display appears to be widespread within the threespine stickleback species complex.