Costly signals can evolve under sexual selection, as only those signals that are difficult to produce and reflect the relative quality of individuals should be important in mate choice. One such signal may be dawn singing behavior in birds. We...
An understanding of diet selection in animals requires knowledge of not only what animals eat in relation to what is available, but also how they perceive the foods available to them. Birds use auditory, visual, olfactory and possibly vibrotactile cues...
We characterized the morphology of mature cuckolder and mature parental male bluegills Lepomis macrochirus from Lake Opinicon, Ontario. By rearing bluegill larvae to maturity in experimental ponds in Illinois we also examined whether morphological differences between males of the two...
We tested the hypothesis that larger individuals in a temperate fish population emerge from winter in better energetic condition than do smaller individuals. We sampled adult male bluegills Lepomis macrochirus in Lake Opinicon, Ontario, after spring ice break and just...
Assessments of population genetic structure and diversity can be of value in formulating management plans for threatened species. Using randomly amplified polymorphic DNA markers, we found evidence of significant genetic structure among black rat snakes ( Elaphe obsoleta) sampled at three...
We found high population densities of Hydra canadensis (up to 30,000 m ‘) on macrophytes in Lake Opinicon (Ontario, Canada) and tested whether they influenced the survival of larval bluegill, Lepomis macrochirus. Hydra were observed to capture and ingest bluegill...
We investigated the relative effects of low pH and high iron on a water mite, Arrenurus manubriator and an aquatic insect, Chironomus riparius. Eggs and active stages were exposed in static renewal toxicity tests to pH 6, 5, 4...
Depending on the circumstances under which extra-pair mating occurs, theory makes opposing predictions about how reproductive synchrony should influence extra-pair paternity. This study investigated which sex initiated extra-pair mating in the yellow warbler, whether extra-pair behaviour and extra-pair paternity were...
Current management strategies for black bass Micropterus spp.—specifically, largemouth bass M. salmoidesand smallmouth bass M. dolomieu—sometimes incorporate regulations with closed fishing seasons during reproductive activities. Our field study investigated how well anglers were complying with Ontario's closed black...
Current management strategies for black bass Micropterus spp.—specifically, largemouth bass M. salmoides and smallmouth bass M. dolomieu—sometimes incorporate regulations with closed fishing seasons during reproductive activities. Our field study investigated how well anglers were complying with Ontario's closed black...
To determine the factors that influence a female's decision of whether or not to re-lay, we removed first clutches from 17 marked female Tree Swallows (Tachycineta bicolor) in a nest-box population in eastern Ontario, Canada. Females and nests...
Chemical lights and gelatin capsules prepared using Cyalume® fluid are widely used by researchers and public educators to mark bats, but may be associated with risks to bats from Cyalume leakage. Newly available 2.9-mm x 24-mm lightsticks weigh significantly less...
Little is known about the breeding biology of the Cerulean Warbler (Dendroica cerulea), a species declining throughout much of its range. However, life history information can provide important insight into the vulnerability of a rare species to habitat disturbance. We...
Phosphorus pratense (Poaceae) has been shown to reduce pollen germination and seed set of heterospecific Poaceae. Danthonia compressa has a mixed breeding system, ie , both cleistogamous and chasmogamous florets. Previous studies revealed that extracts from 1-5 pollen grains of P...
Theory suggests that a male strategy of reducing parental care in response to reduced parentage should evolve only under certain conditions. Expected paternity in subsequent matings is predicted to be primary in effect, because it determines whether there is a...
In this work, we cloned and characterized 60 (GT) repeat microsatellite sequences from the bluegill sunfish geome. We report the frequency distribution, the lengths, and the proportions of the repeat classes for comparison with microsatellites isolated from other teleost, mammal...
Much recent attention has been given to patterns of asymmetry in animals with bilaterally paired characters, and the extent to which such asymmetry might reflect individual quality. Central to much of this research is the assumption that there exists a...
The evolution of distyly from tristyly has occurred repeatedly, especially in the Lythraceae. However, the evolutionary forces involved remain unclear since species exhibiting transitional stages between tristyly and distyly have rarely been studied. The self‐compatible, wetland perennial Decodon verticillatus (Lythraceae)...
In this study we tested the hypothesis that ENS occupancy by Tree Swallows results from avoidance by floaters of nest sites near settled pairs. To date, most explanations of this behavior have assumed that a differential cost to defending the...
Divorcing a current partner to re-pair with a mate of higher quality may be a strategy to increase reproductive success used by socially monogamous birds. By increasing the availability of males through selective mate removal during the nest building period...
In the plant sexual polymorphism tristyly, disassortative mating among floral morphs should result in frequency-dependent selection leading to equal frequencies of the three morphs in populations at equilibrium. Direct evidence for frequency-dependent selection in natural populations is, however, lacking. Here...
Suitable over-wintering habitat is critical to the survival of snake populations at higher latitudes. The identification and protection of traditional, communal hibernation sites (hibernacula) is important for the conservation of threatened species, while the assessment of hibernacula availability may help...
The cumulative (season‐long) incidence of heterospecific pollen transfer (HPT) was examined using nine sympatric species in a midsuccessional old field. Inflorescences were collected weekly during the flowering season, and the proportion of foreign pollen/stigma was recorded. Flowering phenologies of sympatric...
Several hypotheses concerning factors that favour coexistence of female morphs in damselflies (Zygoptera: Odonata) invoke differential attraction to (or harassment of) female morphs from mate-searching males. We designed experiments to determine whether males were differentially attracted to either of two...
Because variation in fat reserves (i.e., condition) is expected to contribute to variation in survival and reproductive success, zoologists often wish to estimate the condition of the animals they study. The conventional condition estimates used for snakes are the residuals...
The adult gypsy moth, Lymantria dispar (Lymantriidae: Noctuoidea) has a pair of metathoracic tympanic ears that each contain a two‐celled auditory chordotonal organ (CO). The earless forest tent caterpillar moth, Malacosoma disstria (Lasiocampidae: Bombycoidea), has a homologous pair of three‐celled...
We used laboratory experiments to show that the nonlethal presence of pumpkinseed sunfish (Lepomis gibbosus) results in smaller size at emergence, decreased growth and development rates, and lower fecundity of the dipteran Chironomus tentans. Smaller size at metamorphosis is often...
Least flycatchers (Empidonax minimus) and American redstarts (Setophaga ruticilla) overlap in the use of food resources on their breeding grounds, promoting high levels of interspecific aggression by the socially dominant flycatcher. We examined the role of...
The effects of temporary male absence during egg laying on the production of extra-pair young by female eastern bluebirds,Sialia sialis, were examined. Females whose mates were removed for 2 days during egg laying produced more extra-pair young than...
Damage to the shoot apex commonly causes release of lateral meristems from apical dominance in plants. This has been shown in some species to promote increased seed and/or biomass production (i.e. overcompensation) by stimulating lateral branching, primarily in plants growing...
The dogbane tiger moth, Cycnia tenera, emits ultrasonic sounds by rhythmically buckling a pair of tymbals when stimulated by pulsed sounds resembling bat echolocation. We monitored the central pattern generator governing this response by recording the motor output of the...
We assessed the frequency of extra-pair paternity (percentage of broods with a least one extra-pair young) in 25 families of tree swallows nesting in natural cavities and compared it to that in a nestbox.
Here we report a male Prairie Warbler (Dendroica discolor) that was found singing a repertoire of both Prairie Warbler and Black-throated Green Warbler (Dendroica virens) songs, and we describe its response to playback of Black-throated Green Warbler song.
In vitro studies were performed to quantify the qutative allelopathic effect of pollen from Phleum pratense (Aveneae: Poacetae). Extract from ground pollen was paritioned, using ion-exchange chromatography.
Evidence of the pathogenicity of haematozoa in wild bird populations is limited, possibly because infected birds alter their behavior to avoid the costs of being parasitized. We tested this hypothesis by examining dominance relationships relative to parasite status in captive...
The dynamics of chrysophyte populations and the onset of encystment in relation to several physical, chemical, and biological variables were studied in two Canadian lakes, Lake Opinicon (LO) and Upper Rock Lake (URL). LO is shallow and polymictic during the...
Evidence from a long-term study of red-winged blackbirds, Agelaius phoenicus, in Washington has indicated that females preferentially nest in territories of males that are familiar with their neighbours, perhaps because familiar males cooperate in nest defence. Data presented here from...
Researchers have questioned whether variation in population density influence the maintenance of two or more morphs within and between insect populations.
Possible convergence between the unique aerial-feeding american redstart and the tyrannid flycatchers was considered using skeleton, external morphology, substrate use, and locomotory feeding movements.
Pollen allelopathy occurs when pollen toxins inhibit sexual reproduction in heterospecifics. To quantify pollen allelopathic effects in vitro, pollen of Hieracium autrantiacum, H. Floribundum and H. Pratense was extracted with double distilled water into concentrationss of pollen grains.
We take issue with a recent study by Gowaty (1993) that finds evidence in support of the idea that fledgling sex ratios in birds are influenced by Local Resource Competition. After controlling for the lack of independence among species due...
We tested whether the reproductive success of male red-winged blackbirds (Agelaius phoeniceus) varied with male secondary sexual traits or with haematozoa prevalence, and whether these patterns were consistent with females preferring genetically superior males. We also determined whether...
Ecomorphological analyses that search for patterns of association between morphological and prey-use data sets will have a greater chance of understanding the causal relationships between form and diet if the morphological variables used have known consequences for feeding performance. We...
Earlier studies have shown that extracts from pollen of Phleurn pratense reduce pollen germination and seed set in Elytrigia repens (L.) Nevski (Poaceae), but the effect of in situ pollen from P. pratense on seed set in E. repens in...
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.
Pairs of captive male brown-headed cowbirds (Molothrus ater) housed with a female formed clear dominance relationships, and when an older male was housed with a yearling male, the adult was usually dominant.
The purpose of the experiments presented here was to determine the location within the central nervous system (CNS) of the proposed tymbal central pattern generator (CPG) in Cycnia tenera. Motor neuron impulses that underlie tymbal activation were recorded extracellularly from...
We used a laboratory experiment to determine effects of a predator (other than straightforward prey consumption) and food availability, during the larval stage, on adult size, age at emergence and fecundity of Chironomus tentans.
Many fish species are protracted spawners, producing fry over a several-week breeding season. We demonstrate that this time dimension has important implications for recruitment by relating the body size and survival of yearlings to the day that they were born.
We report here an estimate of the time of day of egg laying in Eastern Bluebirds using the method developed by Scott (1993) to analyze data we collected during a study of mate guarding (Meek and Robertson 1994).
The winter dynamics of several chemical, physical, and biological variables of a shallow, polymictic lake (Opinicon) are compared to those of a deep, nearby dimictic lake (Upper Rock) during ice cover (January to early April) in 1990 and 1991. Both...
In this study, we used pumpkinseed populations in two east-central Ontario lakes to test for age and size-dependent effects on the probability and timing of reproduction of mature females.
