Analysis of the piscivore guild in fish species-rich lake and stream systems in eastern Ontario showed the co-occurrence of three types: (1) specialists that became piscivorous at the age of a few weeks (Esox, Micropterus); (2) ‘secondary’ piscivores...
Hummingbirds are noted for their hovering flight, and it has been shown that a bird that hovers can move more quickly between flowers than one that perches. Because the relative importance of energetic costs vs. speed increases with body size...
We compared aspects of eastern kingbird (Tyrannus tyrannus) breeding biology between lakeshore and upland habitats in eastern Ontario. Nests were more closely spaced and eggs were laid earlier at the lakeshore than in the uplands. Within the lakeshore...
in situ cylindrical porewater sampler, with interval stackers and a nondegradable membrane, is described. Both horizontal and vertical gradients of dissolved constituents in porewater can be assessed. Sampling at 4-cm intervals within Myriophyllum spicatum root zones showed that steep depletion...
Radio transmitters for implantation in snakes were designed to provide transmitter life in excess of one year. This was achieved by using a 290 mAh, 3.5 V Lithium-Thionyl Chloride battery and a 2 stage transmitter with a thermistor in the...
The role of courtship behaviour in ethological isolation was studied by analysing courtship sequences between different crosses of pumpkinseed (Lepomis gibbosus), bluegill (L. macrochirus), and their hybrid sunfish. Crosses were established in large laboratory tanks, under an artificially advanced photoperiod...
We monitored the time spent at the nest and following behavior of mated tree swallows to determine if males were guarding their mates. The proportion of time spent together at the nest did not decrease significantly between fertile and postfertile...
Phosphate uptake by the blue-green alga Oscillatoria limnetica Lemmerman is stimulated by micromolar concentrations of Ca2". The calmodulin antagonists 4-(3-(2(trifluoromethyl) phenylthiazin-1O-yljpropyl)- I-piperazine ethanol-Ha and its monofluoro-analog inhibit orthophosphate uptake of Oscillatoria limnetica by over 97% implying involvement of calmodulin in...
Fecal sac removal by Tree Swallows (Tachycineta bicolor) was monitored for 10 "land" nest boxes (> 100 m from water) and 13 "water" nest boxes (adjacent to or over water). The mean distance from the nest at which...
The field component of this study compared feeding preferences of Umbra limi with available resources in the environment. The mudminnows preferred benthic coleopterans, anisopterans, and amphipods while avoiding planktonic and other benthic food types. The laboratory component tested for possible...
Growth in the first summer of life was compared in nine coexisting fish species with different life history strategies. Relative to hatching size, the various species grew 6- to 10-fold in length and up to 1000-fold in weight. Growth patterns...
The implications of chemosensory feeding and associated ictalurid morphology were investigated through a seasonal study of the diets of the brown bullhead (Ictalurus nebulosus) and yellow bullhead (I. natalis) relative to food availability. Based on...
Correlations were sought between insect species richness and abundance, and the chemical traits of foliage of 33 species of broad-leaved deciduous trees in southern Ontario. Number of Leipdopteran species collected by the Canadian Forest Insect Survey was not significantly correlated...
The tympanate, arctiid moth,Cycnia tenera responds to pulsed, 30 kHz acoustic stimuli resembling bat echolocation signals by emitting trains of clicks. This phonoresponse was used to determine that this moth is maximally sensitive to stimulus pulse repetition rates of...
Stamps (1978) suggested that the type and extent of parental care can influence the behavioural ontogeny of the offspring. Largemouth bass (Micropterus salmoides) males guard the fry for up to a month after they leave the nest while...
The comment by Peck on our note "A double-brooded Eastern Kingbird" brings up a valid point. Since the female involved was not banded, we cannot be absolutely sure that the same female was responsible for both nests.
The first section of this paper explains how alternative tactics and strategies may be evolutionarily stable within the same environment. The analysis shows that it is theoretically possible for precocial male phenotypes to enjoy fitness equal to late maturing males-long...
Male Nannothemis bella (Uhler) dragonflies are territorial at the breeding site. On the basis of the male behavioural time budgets, the species can be regarded as a territorial percher. Those acts involved in territorial maintenance (patrolling and fighting) are more...
The exotic macrophyte Myriophyllum spicatum spread widely in Lake Opinicon, Ontario, after 1974, dominating the 2.0- to 3.5-m depth zone which had previously been largely open water. In the shallows it formed beds within the species-rich native Potamogeton–Vallisneria...
Relatively little work has been done on the ontogeny of feeding behaviour in fish. One of the aims of this study was to compare the ontogeny of feeding behaviour in four species of centrarchid fish of diverse feeding guilds. A...
A mass encystment of Mallomonas pseudocoronata cells was observed in a polymictic lake from Southern Ontario, Canada. Scanning electron microscopy was used to describe its statospore, which is oval in shape, covered by short spines, and has a short cylindrical collar.
The effect of phytophagous beetles on plant succession in an old—field community in southeastern Ontario was investigated over a 5—yr period. An experimental comparison of insecticide treated and untreated plots indicates that grazing by Trirhabda spp. on the goldenrod Solidago...
Female Red-winged Blackbirds were observed to interact aggressively with conspecific females during the breeding season. Redwing females attempted to repel intruding females through the use of vocalizations, displays, and aggressive chases. Mapped positions of marked individuals indicated that female Red-winged...
The present paper examines how singing is used in territorial communication between neighboring male song sparrows, Melospiza melodia. We concentrate upon the "dynamics" of song behavior, in which shortterm variations in patterns of singing are analyzed from two perspectives...
Although various studies have been carried out on outbreak populations of Malacosoma disstria Huebn there is a paucity of work on between-outbreak populations because of the difficulty of locating the caterpillars. The authors present perliminary evidence which suggests that this...
Red-winged Blackbird (Agelaius phoeniceus) offspring sex ratios at hatch were determined for 97 clutches suffering no egg loss or infertility and produced an overall sex ratio of 1 male: 0.94 females.
Offspring sex ratios varied seasonally, with early...
The effect of plant size on reproductive characteristics was examined in a natural population of Erythronium americanum Ker. The number of ovules, fertilized ovules, unfertilized ovules, aborted seeds, and seeds and the fruit weight were found to be correlated positively...
The dogbane tiger moth (Cycnia tenera Hübner; Arctiidae) responds to ultrasonic, artificial bat echolocation signals by emitting stereotyped trains of high‐frequency, rapidly repeated clicks. By comparing this response in intact and headless moths, the role of protocerebral auditory inter‐neurones...
I analyzed the auditory characteristics of a variety of tympanate moths from areas representing low and high levels of bat (= echolocation signal) diversity. Moths sampled in two African (high diversity) sites reveal significantly higher sensitivities than those analyzed at...
The use of other individual's echolocation calls by little brown bats, Myotis lucifugus, was tested by observing the response of fi'ee-flying bats to presentations of recorded echolocation calls and artificial sounds. Bats responded by approaching conspecific calls while searching...
Communal night roosting behavior of Myotis lucifugus was studied in southeastern Ontario using low light level television equipment. Adult females roosted in groups of up to 37 in five mortices in two barns. Night roosting only occurred on cool nights...
Risks taken by female red‐winged blackbirds (Agelaius phoeniceus) in defence of their young were recorded for individuals with differing past investment but identical expected benefits. Investment was manipulated by switching clutches of equal size between nests differing in...
Seasonal, habitat, and sex-specific food habits of red-winged blackbirds were studied by stomach analysis from March through October 1977 in eastern Ontario. The overall diet is nonspecialized, but within seasons, habitats, or sexes, specializations do occur. In early spring, males...
The auditory sensitivity characteristics of moths sampled in southeastern Ontario and south-central British Columbia were compared in four separate bandwidths from 5 kHz to 110 kHz. British Columbian moths exhibit a significantly greater sensitivity to frequencies from 30 kHz to 75 kHz (midrange) then...
Field experiments were conducted on a population of nesting Tree Swallows (Iridoprocne bicolor) to assess whether the evolved function of territoriality is to prevent breeding by conspecifics (superterritoriality). The size and orientation of territories were estimated...
Bluegill (Lepomis macrochirus) and pumpkinseed (L. gibbosus) sunfish are sympatric over most of the Great Lakes basin and various studies have been car- ried out on the habitat and resource partition- ing of the older age...
The intensity of nest-defence aggression by female redwinged black birds (Agelaius phoeniceus) with eggs decreased late in the breeding season, while aggression at this time increased amongst females defending broods. High predation pressure late in the breeding season decreased the...
The Yellow Warbler (Dendroica petechia) is frequently parasitized by the Brown-headed Cowbird (Molothrus ater) resulting in reduction of nest success at parasitized nests (Schrantz 1943, McGeen 1972). There are several avenues open to a Yellow Warbler once a...
Heat penetration and thermal lag in the submersed soil surrounding the roots of aquatic plants depends on two fundamental thermal properties of the substrate, volumetric heat capacity (CV) and thermal conductivity (k). The relationship of these parameters to the fractions...
In the eighteenth century several natural historians suggested that the seemingly chaotic flight of moths was somehow related to attacks by hunting bats (see Kirby and Spence 1826), but the details of this relationship were clarified only after we under...
Why is parental care performed by the female in some species and the male in others?Several answers have been proposed by theoretical studies (Trivers,1972;Williams,1975;Dawkins and Carlisle, 1976;Maynard Smith,1977, 1978;Perrone and Zaret,1979), but there have been few efforts to test alternative...
Male bluegill sunfish (Lepomis macrochirus) construct nests in densely packed colonies characterized by high breeding synchrony. Females deposit eggs in the nests and males alone provide parental care for eggs and larvae. During the 7-day care period, males...
The use of frequency, duration, and patterns of frequency change over time to identify 39 species of North American and African bats by their search phase echolocation calls is described. The data were obtained from an oscilloscope display of the...
Responses of nonflying moths to ultrasound: the threat of gleaning bats. Can. J. Zool. 59: 525-529. Stationary and walking tympanate moths (Arctiidae, Geometridae, Noctuidae, and Notodontidae) exhibited discrete behavioural responses to electronically simulated bat echolocation calls. The presence of a...
Organisms which reproduce sexually may often provide differing relative investments in offspring of the two sexes,and factors influencing the proportions of these investments are poorly understood.Theoretical discussions (Trivers,1972; Charnov,1979) have rarely been supported by adequate field evidence (but see Cowan,1978...
Using fixed stimulus dummies as territory intruders, we studied the spatial distributions of the aggressive responses made by nesting male pumpkinseed sunfish. Results replicated over three field seasons indicate that males defend two territory boundaries concurrently, depending on whether an...
Lateral-body bar marking differences can be used for identifying young-of-year bluegills and pumpkinseeds. The young-of-year of both species were reared in the laboratory from eggs and examined weekly for lateral-body bar pigmentation development. Pumpkinseeds were found to develop spots between...
Male bluegill sunfish are shown to have two alternative mating strategies: cuckoldry or parental care. Cuckolder males first mature at age 2. They follow a developmental sequence of sneaking and then mimicking female behavior to deceptively gain access to spawnings...
We used neurophysiological analyses to determine that arctiid moths which emerge, as adults, during the spring possess tympanic organs responsive to ultrasonic stimuli similar to the echolocation signals of bats. These species, however, do not express another form of bat-directed...
Injection of male bullheads (Ameiurus nebulosus) with estradiol induced the production of a major serum phosphoprotein of molecular weight 145 000. This protein was immunoprecipitable by antisera raised against lipovitellin from bullhead eggs and was absent from the...
Young fish of six species in an open water community all began their exogenous feeding by taking nauplii and small cyclopoids of body length (less tail) of 0.1–0.3 mm. Appearance of larvae of the different species in the system was...
The reproductive behavior of rock bass in Lake Opinicon begins with an abrupt movement of mature males to inshore nesting areas. Inshore density increases several fold and males become territorial, defending a bottom area in which they construct a nest...
The rim circling (RC), and aggressive habituation of nesting bluegills were studied in natural colonies during the six days of the reproductive period following spawning. To examine the stimulus specificity of aggressive habituation, selected test individuals and four neighbors were...
A total of twenty-six allozyme loci were assayed in six crayfish species. Estimated mean heterozygosity was low (5.5 percent) for all species in comparison with the invertebrate average. The specific values, however, ranged from 2.9 percent to 8.3 percent. These...
The auditory characteristics of the arctiid moth, Cycnia tenera were examined using two behavioral criteria, sound production and flight cessation. The majority of the individuals tested indicated a maximum sensitivity to frequencies between 30 and 50 kHz although there is...
Ages determined by counts of apparent annuli on scales, sagittae, vertebrae, pectoral fin ray and dorsal fin spine cross sections of largemouth bass from northern populations, which are older and slower growing fish than in the southern parts of its...
