Competition among males to mate is generally associated with male-biased size dimorphism. In this study we examine mating behavior in the northern water snake (Nerodia sipedon), a species in which males are much smaller than females despite substantial competition among...
Black-capped Chickadees (Parus atricapillus) sing a two-note song termed fee bee. Frequency descends within the fee note and between the fee and bee notes. Within-song frequency ratios are highly invariant, while among songs, absolute frequency is variable. We conducted sound-transmission...
This paper presents results from a series of studies investigating the causes underlying uneven style morph ratios in tristylous Decodon verticillatus, a clonal perennial that inhabits wetland habitats in eastern central North America.
This study on black-capped chickadees, Parus atricapillus, assesses whether social rank influences the behaviour of chickadees in predator situations. Chickadee flocks were restricted to an area of an outdoor aviary containing no vegetative cover to ensure that all flock...
The coverable badge hypothesis predicts that non-territorial floaters should conceal their badges and that territory owners should expose their badges. Evidence is presented that suggests owners also benefit by concealing their badges at certain times. Forty territorial male red-winged blackbirds...
The sensory exploitation hypothesis for male courtship trembling was tested by constructing a cladogram of N. Papillator plus nine confamilial ingroup species and three outgroup species using 28 morphological and behavioural characters. Courtship and predatory behaviour were mapped onto the...
Diel and spring/summer space-use and feeding patterns were investigated in an assemblage dominated by five fish species occupying the offshore waters of Lake Opinicon, a shallow mesotrophic lake in southeastern Ontario. We assessed fish distribution and diel movement in May...
We tested whether payoff asymmetries could explain why "floater" red-winged blackbirds seldom escalate contests to acquire territories. We removed territorial male "owners" and allowed floater replacements to claim territories. We then released owners to see how three currencies of payoff...
We describe a technique and apparatus for extracting blood samples from birds in the field. We tested the effect of our technique on the health and behavior of captive Brown-headed Cowbirds (Molothrus ater) and free-living Red-winged Blackbirds (...
In this study conducted in southeastern Ontario, Canada, we manipulated the length of outer tail feathers (streamers) of male barn swallows (Hirundo rustica) shortly after they returned to four small breeding colonies in the spring.
Data from a 3-year study of red-winged blackbirds (Agelaius phoeniceus) were used to test the hypothesis that parasites (in this case, haematozoa) reduce male fitness and cause diminished expression of secondary sexual traits, which, in turn, are used by females...
In this study, potential cues for detachment of parasitic larval Arrenurus danbyensis Mullen mites from Coquillettidia perturbans (Walker) mosquitoes were investigated. Contact with water did not induce a dramatic rate of dissociation. Crushing the host's abdomen was not as effective...
We found that larval damselflies actively defended against colonization by larval water mites (Arrenurus spp.) and that developmental stage of damselflies was related to their likelihood of being colonized. Because larval mites have a phoretic stage on damselflies, it...
Male bluegill (Lepomis macrochirus) display a complex reproductive behavior involving two alternative life history pathways: delay of sexual maturation to become “parentals” or precocious maturation as “cuckolders.” The purpose of our study was to investigate the association of...
A chlorobenzoate-degrading Alcaligenes strain, BR60, was introduced to flowthrough lake microcosms and exposed to 3-chlorobenzoate (3Cba) concentrations from 0 to 25 μM. A DNA probe specific for BR60 chlorobenzoate catabolic genes was used with the most probable number (MPN) technique...
Certain families of atympanate (deaf) moths are more abundant during the summer at times when bat activity is low. Atympanate moths were collected at ultraviolet lights throughout the summer at a site in southeastern Ontario. Seasonal frequency distributions for individual...
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...
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)...
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...
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...
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...
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...
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...
1. As part of an overall study of the social behavior of the little brown bat, Myotis lucifugus, we compiled the vocal repertoire of this gregarious species in its natural habitat. Ten vocalizations were identified and associated with certain behavioral...
The purpose of this study was to determine whether the yellow warbler (Dendroica petechia) derives any benefits from nesting in close proximity to its own and other species in reducing predator pressure or the incidence of brood parasitism...
The histology and carbohydrate histochemistry of eight teleostean stomachs are compared. Three gross anatomical types of stomachs are described and their shapes appear to correlate somewhat with feeding habits. Each type can be divided histologically into a corpus and pylorus...
The strip count method of determining fish densities was investigated for a small lake in a series of inshore sites that differed in their physical and biological characteristics and in the communities of fishes present. Overall total numbers of fish...
The histology and carbohydrate histochemistry of ten teleostean esophagi were compared. Structurally, the four layers of a typical vertebrate digestive tract were consistently present. The epithelium was always stratified and in all but one species (Ictalurus nebulosus) contained taste buds.
Drawing on work with passerine birds, investigations on the self‐selection of photoperiod in a constant environment by pumpkinseed sunfish (Lepomis gibbosus) capable of controlling their lighting have been carried out. Each aquarium with lighting equipment was set up in a...
Free-swimming larvae of five perciform species were collected with tow nets in large numbers in Lake Opinicon from May to August of 1969 and 1970. The species appeared in the same seasonal sequence during the 2 yr: first yellow perch (...
"Swarming" refers to the summer nocturnal flights through hibernacula by the five species of bats known to hibernate locally. A total of 6400 bats was handled during studies of swarming at 10 hibernacula in Ontario and Quebec from 1966 to...
