Morphologie bucco-linguale d'une guilde de canards barboteurs

1986 ◽  
Vol 64 (10) ◽  
pp. 2176-2180 ◽  
Author(s):  
Serge Tremblay ◽  
Richard Couture
Keyword(s):  
Resource Partitioning ◽  
Anas Platyrhynchos ◽  
Morphological Characters ◽  
Food Resources ◽  
Average Weight ◽  
Dabbling Ducks ◽  
Interspecific Differences ◽  
Interspecific Variations ◽  
Duck Species ◽  
Black Duck

Interspecific variations of bucco-lingual characteristics were measured in a guild of dabbling ducks and the influence of these characteristics on the use of food resources was studied. Morphological characters of the bill and tongue were measured in eight species of dabbling ducks of the genus Anas. Our results show that there are interspecific differences in the bucco-lingual characteristics of all species studied except for the Black Duck (Anas rubripes) and the Mallard (Anas platyrhynchos). There was a significant correlation between the density of bill lamellae and the weight of the species (r = −0.935, P < 0.01). In six species, the density of the lamellae was correlated with the volumetric index of the bill (r = −0.960, P < 0.01). These results indicate that in species with large bills the density of the lamellae is low, whereas in species with small bills, the number of lamellae is high. The volumetric index of the bill was significantly related to the average weight of each duck species (r = −0.905, P < 0.01). Dabbling ducks that filter benthic material can thus be classified on a scale based on lamellar density and bill volume. The differences in bucco-lingual morphlogical characters seem to reflect a mode of resource partitioning that diminishes competition.[Journal translation]

Hybridization between the Mallard and native dabbling ducks: causes, consequences and management.

2014 ◽  
Vol 20 (1) ◽  
pp. 41 ◽  
Author(s):  
P-J Guay ◽  
A Taysom ◽  
R Robinson ◽  
J P Tracey
Keyword(s):  
Introduced Species ◽  
Anas Platyrhynchos ◽  
Management Strategies ◽  
Dabbling Ducks ◽  
Monitoring Techniques ◽  
Duck Species ◽  
Black Duck ◽  
Dabbling Duck ◽  
The Pacific ◽  
The World

Waterbirds are currently facing various threats throughout the world. One threat that is often overlooked is hybridization with introduced species. This threatening process is especially significant for dabbling ducks (Genus Anas). The Mallard (Anas platyrhynchos) has been introduced to various parts of the world and now hybridizes and threatens numerous Anas species. In this paper, we review hybridization between Mallards and dabbling ducks with a specific emphasis on threats to the Pacific Black Duck (A. superciliosa). We then present an overview of the potential mechanisms of hybridization and discuss monitoring techniques. We conclude by proposing management strategies and speculating on the future of native dabbling duck species.

Shell partitioning of two sympatric hermit crabs, Pagurus middendorffii and P. brachiomastus, in north-eastern Hokkaido, Japan

2007 ◽  
Vol 88 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Takashi Oba ◽  
Satoshi Wada ◽  
Seiji Goshima
Keyword(s):  
Resource Partitioning ◽  
Reproductive Period ◽  
Hermit Crabs ◽  
Interspecific Difference ◽  
Spatial Distributions ◽  
Utilization Pattern ◽  
Interspecific Differences ◽  
North Eastern ◽  
Body Sizes ◽  
Utilization Patterns

The distribution, reproductive biology and shell utilization pattern of two sympatric hermit crab species in Akkeshi, north-eastern Hokkaido, were examined. Although spatial distributions of Pagurus middendorffii and P. brachiomastus highly overlapped and their body sizes were similar, their shell utilization and breeding season markedly differed. Since interspecific differences in the shell utilization pattern agreed with the experimentally determined shell preference difference, we conclude that the interspecific difference in shell preference results in the shell utilization patterns observed in the field. The interspecific difference in the reproductive period, shell utilization pattern and shell preference are concluded to be factors that allow the coexistence of the two Pagurus species in Akkeshi. This study is an example of resource partitioning by coexisting hermit crabs.

Effects of a carbaryl-induced depression in invertebrate abundance on the growth and behavior of American black duck and mallard ducklings

1984 ◽  
Vol 62 (3) ◽  
pp. 452-456 ◽  
Author(s):  
Malcolm L. Hunter Jr. ◽  
Jack W. Witham ◽  
Hilary Dow
Keyword(s):  
Active Ingredient ◽  
Growth Rates ◽  
Anas Platyrhynchos ◽  
Anas Rubripes ◽  
Black Duck ◽  
Invertebrate Abundance ◽  
American Black ◽  
American Black Duck ◽  
And Behavior ◽  
Rate Of Movement

Aerially spraying ponds with carbaryl (Sevin-4-oilR) at 840 g active ingredient/ha reduced biomass and numbers of macroinvertebrates and decreased the growth rates of American black duck, Anas rubripes, and mallard. Anas platyrhynchos, ducklings in Maine. Ducklings on sprayed ponds spent more time searching for food and less time resting, and their rate of movement around the ponds was greater than for ducklings on unsprayed ponds.

scholarly journals Susceptibility of the Japanese beetle, Popillia japonica (Newman) (Coleoptera: Scarabaeidae), to entomopathogenic Hypocreales fungi

2015 ◽  
Vol 95 (1) ◽  
pp. 1-6 ◽  
Author(s):  
François Giroux ◽  
Robert Lavallée ◽  
Éric Bauce ◽  
Claude Guertin
Keyword(s):  
Biological Control Agent ◽  
Larval Mortality ◽  
Control Agent ◽  
Popillia Japonica ◽  
Japanese Beetle ◽  
Interspecific Differences ◽  
Interspecific Variations ◽  
Significant Difference ◽  
Lecanicillium Longisporum ◽  
Laboratory Bioassays

The susceptibility of adults and larvae of the Japanese beetle to isolates of the fungi Beauveria bassiana, B. brongniartii, Metarhizium anisopliae, Lecanicillium longisporum and L. muscarium (Ascomycota: Hypocreales) was evaluated in laboratory bioassays. The presence of intra- and interspecific variations regarding the pathogenicity of the isolates was investigated. Results show that most of the fungal isolates caused mortality in adults and larvae. Isolates M. anisopliae INRS 705 and B. bassiana INRS 236 induced 70.3% and 65.2% of mortality in P. japonica adults, respectively, and both caused the death of about 37% of larvae. Of the 17 tested isolates, 13 caused larval mortality. However, no significant difference was found between the susceptibility of larvae to isolates from different species and those from a same species. Lecanicillium species are undoubtedly not pathogenic to adults and seem to have few effects on larvae. Based on the results obtained with the selected isolates, intra- and interspecific differences relative to the pathogenicity of the isolates appeared to be present. Overall, this study expanded the knowledge about P. japonica susceptibility towards entomopathogenic Hypocreales fungi. The implications of this study regarding the development of a biological control agent are discussed.

scholarly journals Coexistence and resource partitioning in two species of darters (Percidae), Etheostoma nigrum and Percina maculata

1979 ◽  
Vol 57 (10) ◽  
pp. 2061-2071 ◽  
Author(s):  
Heather J. Smart ◽  
John H. Gee
Keyword(s):  
Aquatic Insects ◽  
Resource Partitioning ◽  
Vertical Component ◽  
Food Resources ◽  
Swim Bladder ◽  
Gill Rakers ◽  
Modes Of Life ◽  
Dimensions Of Space

This study investigated partitioning of resources along the dimensions of space, food, and time by johnny darters (Etheostoma nigrum) and blackside darters (Percina maculata). Although both species were abundant in the midcourse of the Whitemouth River and occurred together in all habitats, space was partitioned on a vertical basis. Johnny darters were exclusively benthic whereas blackside darters were much less restricted to the bottom. The latter retained a well developed swim bladder permitting use of the vertical component of the environment. Partitioning of food resources occurred and although similar taxa were consumed by both species (aquatic insects and Crustacea) the proportions were not similar. Johnny darters fed mainly on benthic items whereas blackside darters ate pelagic items. Differences in protrusibility of premaxilla, position of the mouth and eyes, retinal acuity, and number and morphology of gill rakers reflected different modes of life. There was no evidence of partitioning by time.

Variation saisonnière dans la répartition des ressources alimentaires entre cinq espèces de poissons en fonction de la disponibilité des proies

1992 ◽  
Vol 70 (4) ◽  
pp. 796-803 ◽  
Author(s):  
Élyse Harnois ◽  
Richard Couture ◽  
Pierre Magnan
Keyword(s):  
Resource Partitioning ◽  
Yellow Perch ◽  
Perca Flavescens ◽  
Food Resources ◽  
Resource Abundance ◽  
Variation Saisonnière ◽  
Golden Shiner ◽  
Food Overlap ◽  
High Degree ◽  
Benthic Resources

We observed that yellow perch, Perca flavescens, golden shiner, Notemigonus crysoleucas, spottail shiner, Notropis hudsonius, and log perch, Percina caprodes, partitioned food resources in relation to resource abundance in a small bay of Lake Saint-Pierre, Quebec. When the abundance of benthic resources was at its lowest, in May 1988, the fish showed a very low overlap in their diet. In contrast, when these resources were most abundant, in August 1988, the four species had a high degree of food overlap. Two other sampling periods, in June and July, revealed intermediate situations. A fifth species, the silvery minnow, Hybognathus nuchalis, was phytophagous and, therefore, did not compete with the other species for food resources. An ecomorphological analysis of the first four species suggests that these partition food resources according to their functional morphology. Our results support Schoener's hypothesis, which states that the intensity of interspecific competition, in terms of resource partitioning, varies according to the abundance of these resources.

scholarly journals Food Habits of Migratory Ducks in Illinois

1959 ◽  
Vol 27 (1-6) ◽  
pp. 289-344 ◽  
Author(s):  
Harry G. Anderson
Keyword(s):  
Mississippi River ◽  
Illinois River ◽  
Wild Plants ◽  
Cultivated Plants ◽  
Lesser Scaup ◽  
Duck Species ◽  
Black Duck ◽  
Long Time ◽  
Ruddy Duck ◽  
Wood Duck

As a basis for an effective, long-time program of management for the waterfowl of the Mississippi Flyway, detailed information about the diet of ducks that migrate through Illinois was considered essential. In the autumns of 1938, 1939, and 1940, duck gizzards totaling 4,977 were collected from hunting clubs and individual hunters at 21 sites along the Illinois River between Ottawa and Florence and 11 sites along the Mississippi River between Rock Island and Quincy. The following 17 duck species were represented: mallard, pintail, green-winged teal, blue-winged teal, baldpate, gadwall, shoveler, black duck, wood duck, lesser scaup, ring-necked duck, redhead, canvasback, ruddy duck, greater scaup, common goldeneye, and oldsquaw. The analyses indicated that, during the fall, most species of ducks in Illinois are predominantly vegetarians, that most of them feed principally on native wild plants, and that the lesser scaup is the only species with a diet predominantly animal. Of the 95 wild plants and 4 cultivated plants found in the gizzards and identified to species, the following 19 were most important: corn, rice cutgrass, marsh smartweed, coontail, wild millet, longleaf pondweed, red-rooted nut-grass, waterhemp, nodding smartweed, buttonbush, large-seeded smartweed, nut-grass, chufa, Walter's millet, sago pondweed, duckpotato, river-bulrush, teal grass, and giant bur-reed. Snails and mussels provided the largest animal food volume and occurred in the largest number of gizzards. Insects were second in volume and occurrence. More than 200 of the gizzards examined contained lead shot pellets that had been ingested.

scholarly journals Temporal Flexibility of Reproduction in Temperate-Breeding Dabbling Ducks

The Auk ◽  
2000 ◽  
Vol 117 (3) ◽  
pp. 640-650 ◽  
Author(s):  
Gary L. Krapu
Keyword(s):  
Late Summer ◽  
The United States ◽  
Dabbling Ducks ◽  
Anas Discors ◽  
Interspecific Differences ◽  
Temporal Flexibility ◽  
Anas Clypeata ◽  
Northern Pintails ◽  
Anas Strepera

AbstractI compared nesting intervals during three consecutive years in five species of temperate-nesting dabbling ducks (Mallard [Anas platyrhynchos], Northern Pintail [Anas acuta], Northern Shoveler [Anas clypeata], Blue-winged Teal [Anas discors], Gadwall [Anas strepera]) and assessed whether differences existed in timing of refractoriness. Most nesting by females of all five species ended by the summer solstice. Nesting ended earliest for Northern Shovelers and Northern Pintails and latest for Gadwalls. Some Mallards, Blue-winged Teal, and Gadwalls continued to nest into mid- and late summer, whereas Northern Shovelers and Northern Pintails did not. Mallards, Blue-winged Teal, and Gadwalls accounted for 99% (81 of 82) of flightless broods resulting from nests initiated during mid- or late summer in North Dakota and 98% (58 of 59) of flightless juveniles shot on or after 1 October by a random sample of duck hunters from across the United States. Early cessation of breeding by Northern Shovelers may have evolved in response to the species' limited flexibility in diet. Photorefractory mechanisms that limit most breeding to spring presumably evolved in response to severe constraints on reproductive success when nesting continued through summer (e.g. mortality of late-hatched young and molting females due to low temperatures). Interspecific differences in photosensitivity may account for variation in timing of cessation of nesting in late spring, but controlled experiments are needed to assess the possible role of non-photic influences. My results suggest that the refractory mechanisms controlling length of the breeding season in temperate-nesting dabbling ducks are more varied and complex than previously thought, with non-photic influences (e.g. water conditions, food availability, food quality) having a larger role than indicated by earlier research.

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