In many species of birds, clutch size decreases as the season progresses, but this is confounded by the fact that young birds not only often have smaller clutches but also breed later than older females. We examined the effect of...
Hole nesting birds can be difficult to capture at natural nest sites because cavities are inaccessible due to the height of a cavity or burrow above the ground or because of tree decay. For this reason, we created a manually...
We conducted daily censuses on a marked population of the damselfly Calopteryx maculata for two complete breeding seasons to document the reproductive tactics of individual males. Overall, 78% of the 600 males studied defended territories and 14% of those territorial...
There are large numbers of reproductively mature female tree swallows (Tachycineta bicolor) which do not breed due to limits of suitable nesting cavities. Many of these floaters are one-year-old females that have a distinctive subadult plumage. This study...
In resource-defence mating systems we intuitively expect that the most competitive males should win the best resources so that, in territorial species, male quality and territory quality will be highly correlated. In the "polygyny threshold model" (PTM) of mate choice...
The order in which females settle on territories likely reflects patterns of female choice of territory and/or mates. Yet in most studies of female choice, settlement dates are usually only inferred from dates of nest initiation or first egg date...
Young-of-the-year largemouth bass, Micropterus salmoides, were exposed to four concentrations of sulphuric acid (pH levels 7.2, 6.1, 4.8, and 3.7) for 30 days, and the frequencies of feeding acts and activity bouts, and time budgets were recorded. Juveniles at...
The ideal dominance distribution model predicts that competition between individuals of a species for territories will result in socially dominant individuals acquiring territories in higher quality habitat than their subordinates. Although the dispersion and relative reproductive success of male red-winged...
Largemouth bass Micropterus salmoides were reared over their first 8 weeks of free‐swimming life in uncontaminated control water or in water containing one of five concentrations of pentachlorophenol (PCP) ranging from 1.6 to 88 μg/L. Over the final 3...
Individual male Yellow Warblers (Dendroica petechia) exhibit differences in their level of parental investment, which correlate with the amount of brown streaking on the breast. We tested two alternative hypotheses to explain these patterns. The age effect hypothesis...
A demonstration of adaptive mate choice by females in resource-defence mating systems requires clear predictions as to how females should rank "breeding situations" (defined by the quality of both the resident male and the territory he defends) so as to...
In an eastern Ontario population of red-winged blackbirds, Agelaius phoeniceus, some males were unsuccessful in obtaining a breeding territory and consequently existed as 'floaters'. However, not all floaters were inferior to territory owners with respect to two morphological correlates...
The foraging behavior of the pollinators of tristylous Pontederia cordata was studied to determine if differences in floral morphology would lead to preferential visitation of the floral morphs. Although nectar production is not different in the three floral morphs, differences...
Young (35-50 mm, standard length) bluegills Lepomis macrochirus are restricted to vegetated habitats by predation pressure. Vegetation provides refuge by hindering predator foraging success. In this study, we tested the ability of bluegills to actively perceive and select densities of...
Delayed plumage maturation in males is relatively common among North American passerines, but the Tree Swallow (Tachycineta bicolor) is one of few species in which 1-yr-old females have a distinct subadult plumage. Although they are reproductively mature, most...
The amount of ferric hydroxide plaque deposited on Typha latifolia roots varied between wetlands submerged throughout the growing season. Plaque formation was positively correlated with extractable iron in the substrate and pH, and negatively correlated with the percent organic matter...
Shoals of 3, 5, 7, 10, 15, and 20 bluntnose minnows, Pimephales notatus, were allowed to forage in the absence and presence of a fish predator, which was separated from the shoal by a clear plexiglass partition. A typical...
Studies of brown-headed cowbirds (Molothrus ater) suggest that yearling males are as successful at acquiring mates as adult males. Our aim in this study was to determine if dominance status of males was also independent of age when...
We present data on two methods of sexing adult Tree Swallows before they develop a brood patch or cloacal protuberance. Based on measurements of 219 adults, 100% of the birds with a brown forehead (N = 85) were females. Among...
A three year study (1981 to 1983) was conducted to determine possible influences of wetland acidification on the reproduction and growth of the Eastern Kingbird (Tyrannus tyrannus). This species uses emergent aquatic insect prey to feed its nestlings. Egg characteristics and...
Energy content and fruiting patterns were examined for eight species in the genus Vaccinium Section Cyanococcus, the blueberries. Blueberries varied in both seed and berry production. Fresh fruit contained approximately 85 % moisture. A mg of dried pulp yielded...
We investigated the division of labor in male and female tree swallows by measuring the rate of food delivery to nestlings at 36 nests. By observing natural nests and performing brood manipulations we found that males and females divided the...
Growth energy build‐up and partitioning by immature bluegill sunfish were studied over the summer months from May to September 1984. Fish sampled in May showed low condition and low lipid reserves. Condition was restored to summer levels within the following...
We conducted laboratory experiments to determine if juveniles of three species of centrarchid fishes displayed abilities for species or individual recognition. In one experiment we reared rock bass (Ambloplites rupestris) in social isolation and in social groups. Both...
Observations of radio-tagged Brown-headed Cowbirds (Molothrus ater) indicated that individual males and females engage in extended associations through the breeding season. Persistent courtship by males directed at particular females and extended time spent together by certain males and...
Two groups of largemouth bass, Micropterus salmoides, were reared in the laboratory. One group was reared on an artificial, passive diet (frozen brine shrimp) whereas the second was reared on a natural, active diet (cultured zooplankton). Observations on the...
In each of 4 years of study of a breeding population of song sparrows (Melospiza melodia) approximately two-thirds of the males holding territories at the beginning of the breeding season had abandoned those territories before the end of...
Superterritoriality is a spiteful behavior in which an individual’s relative fitness is improved by reducing the fitness of others through inhibiting them from breeding, rather than through an absolute increase in fitness (Verner 1977). Tree Swallows (Tachycineta bicolor)...
Handling time for prey of different sizes and morphological types was studied in the largemouth bass (Micropterus salmoides). Prey ranged in size from about 1/10 to 2/3 the length of the bass. Handling time increased rapidly with prey...
Whip-poor-wills (Caprimulgus vociferus) showed significantly higher levels of locomotory, vocal, and nest activity during twilight and bright moonlight than under moonless conditions. Field observations and nest record card data indicated that Caprimulgus species usually synchronize their reproductive cycle...
Patterns of food use and food availability were analysed in a species rich summer weedbed community of juvenile lake fish to elucidate ontogenetic and ecological adaptations facilitating species co-existence and rapid growth. It was found that: (a) the community was...
Seventy-two plants of Vaccinium angustifolium, 24 from Newfoundland, 24 from Nova Scotia and 24 from Ontario, were set out in equal numbers on the Nova Scotian mainland and eastern Ontario in order to monitor differences in vegetative and reproductive...
We examined the continuous variation in the breeding plumage of male yellow warblers (Dendroica petechia) to determine if the amount of brown streaking on the breast functions as a badge of relative status in territorial males. Conspecific mounts...
Using plausible assumptions, we propose "transitive odds" and "intrinsic preferences" models of food preference transitivity to account for observed behaviour when animals are feeding on items of pairs of food types from a set of such types for which preferences...
Breeding female cowbirds at the Queen's University Biological Station are often aggressive when encountering other females within their ranges, but they do not defend exclusive territories. The likelihood of aggression appears to be a function of two factors. First, females...
From late May to mid-September 1982 we investigated habital selection by black rat snakes (Elaphe o. obsoleta) at the Queen's University Biological Station in eastern Ontario. We implanted radio transmitters in 4 male and 3 female snakes and...
We compared the ontogeny of feeding in two centrarchid species and hypothesised that the ontogeny of early feeding in the black crappie, Pomoxis nigromaculatus, would differ from that of the smallmouth bass, Micropterus dolomieui, and that the smaller...
Observations of territorial behaviour of male Nannothemis bella indicated that females only laid eggs on males' territories after copulating with the territory holder. Results of daily censuses of marked individuals on a study area suggested that a distinct subpopulation within...
Pentachlorophenol (PCP), a biocide used frequently in the wood preservation industry, is present at detectable levels in many bodies of freshwater (Jones 1981). Because of its wide use and the possibility of contamination of non-target organisms much is known about...
Tree Swallows (Tachycineta bicolor) are hole nesters that are often limited by nest site availability (Holroyd, Can. Field-Nat. 89:60-64, 1975). Populations generally increase following the erection of nest boxes (Low, Bird-Banding 3:76-87, 1933; Chapman, Bird- Banding 6:45-57, 1935...
The lichen flora was sampled at each of the five sites on a near-vertical gneiss rock face. The sites were ranked according to the degree of weathering of the rock surface and were taken to represent different stages in a...
Darwin proposed that the function of the stamen‐style polymorphism in heterostylous plants is to increase the probability of legitimate (compatible) pollinations among the floral morphs. Conspicuous pollen trimorphism in tristylous Pontederia cordata enables a test of the hypothesis. Comparison of...
We review parental investment decision theory and provide an experimental test of the decision rule used by male bluegill sunfish (Lepomis macrochirus) in allocating parental investment to their young. The alternative decision rules tested are: (1) invest according...
A littoral zone assemblage of six planktivorous fishes (Pimephales notatus, Notropis heterodon, Fundulus diaphanus, Lepomis macrochirus, Ambloplites rupestris, Perca flavescens), and five zooplankter species, was analysed relative to three hypotheses concerning prey consumption...
In order to determine the preferred dispersion of a population of breeding Tree Swallows (Tachycineta bicolor) in Ontario, we set up an abundant supply of nest boxes with a variety of distances between them. The 72 boxes were...
Laboratory studies were conducted on 15 schools of blackchin shiners, Notropis heterodon, to determine if they altered their structure in response to changing environmental demands. The hypothesis tested was that fish schools should sacrifice a flat, hydrodynamically efficient structure...
Egg sex, size, and laying sequence were determined for 44 three-egg and 129 four-egg Red-winged Blackbird (Agelaius phoeniceus) clutches collected in 1982 and 1983. The proportion of males decreased with laying sequence in three-egg clutches and increased with...
Male yellow warblers (Dendroica petechia) exhibit extensive variation in the amount and conspicuousness of the sexually distinctive brown streaking on the breast. We investigated this intraspecific variation in degree of sexual dichromatism to see if male plumage rank...
(1) We used 8 years of data on breeding eastern kingbirds (Tyrannus tyrannus) to test whether breeding success is consistent between years at a site, thus enabling birds to use past reproductive success at a site as a...
Male song sparrows in southeastern Ontario have repertoires of five to 11 distinct song types. The singer repeats each song type a variable number of times before switching to another type. Analysis of territorial singing suggested that rate of switching...
Ecological studies using measures of overlap or similarity often treat these measures as free of sampling error. If sample sizes are relatively small, however, the estimates of overlap may not be accurate, and misleading interpretations may result. Two methods are...
Studies on the ontogeny of behaviour in fish have seldom considered the adaptive significance of the order of appearance of the behaviours. Results of laboratory studies and field observations on the ontogeny of feeding, predator-avoidance, and agonistic behaviour in largemouth...
The growth and feeding behaviour of individually held underyearling largemouth bass (Micropterus salmoides) exposed to 50 μg/l pentachlorophenol (PCP) was monitored over a 7-day period which followed a 7-day acclimation period to the experimental conditions. Exposure to PCP...
