When the shoot apical meristem of plants is damaged or removed, fecundity and/or plant growth may suffer (under-compensation), remain unaffected (compensation) or increase (overcompensation). The latter signifies a potential ‘cost’ of apical dominance. Using natural populations of 19 herbaceous angiosperm...
Testing the full impact of neighbourhood crowding within natural vegetation requires more than just effects incurred by established plants. It must also include measurements that take into account suppressive effects on the earliest plant life stages of resident individuals —...
Behavioral responses to alarm cues in aquatic species are typically examined with emphasis on the potential survival benefits accrued by conspecific receivers. By contrast, heterospecific responses to alarm cues and changes in responses with ontogeny in fishes are relatively unexplored...
Phenology match–mismatch usually refers to the extent of an organism's ability to match reproduction with peaks in food availability, but when mismatch occurs, it may indicate a response to another selective pressure. We assess the value of matching reproductive timing...
In lakes and rivers of eastern Ontario (Canada) commercial fishers use hoop nets to target a variety of fishes, but incidentally capture non-target (i.e., bycatch) gamefish species such as northern pike (Esox lucius). Little is known about the...
By examining the mechanical properties of the tympanum of the noctuid moth, Noctua pronuba, Windmill et al. (2006) suggested that this insect increases (up-tunes) the frequencies of its best hearing when exposed to high intensity sounds (HIS) resembling the...
The study of sexual selection has traditionally focused on events and behaviours immediately surrounding copulation. In this study, we examine whether carry-over effects from the non-breeding season can influence the process of sexual selection in a long-distance migratory bird, the...
Parental care requires a complex integration of physiology and behaviour, yet little is known about the physiological and energetic consequences or correlates of these behaviours. Using two species of male black bass (smallmouth bass, Micropterus dolomieu; largemouth bass, M...
Natal dispersal, the process through which immature individuals permanently depart their natal area in search of new sites, is integral to the ecology and evolution of animals. Insights about the underlying causes of natal dispersal arise mainly from research on...
Genetic studies have indicated that some parasite species formerly thought to be generalists are complexes of morphologically similar species, each appearing to specialize on different host species. Studies on such species are needed to obtain ecological and parasitological data to...
Sex ratio biases in avian species remain controversial, although several studies have documented apparent facultative adjustment of offspring sex ratios. While hybridizing pied and collared flycatchers have exhibited sex ratio skews that may be a response to sex‐based costs associated...
We investigated the relationship between predator detection threshold and antipredator behaviour in noctuoid moths. Moths with ears sensitive to the echolocation calls of insectivorous bats use avoidance manoeuvres in flight to evade these predators. Earless moths generally fly less than...
Zebra mussels (Dreissena polymorpha) derive their energy from the pelagic energy pathway by filtering plankton. Because zebra mussels occur in high densities in littoral habitats, they potentially constitute an important trophic link between littoral consumers and pelagic energy...
Females involved in extrapair mating are generally thought to obtain indirect benefits through increased offspring quality. We investigated this in the barn swallow, Hirundo rustica, a socially monogamous passerine in which females seem to have a preference for elaborately...
The bulk of Lake Opinicon fish biomass is concentrated in the physically diverse inshore areas. Quantitative analysis of the community compositions of the various inshore habitat types (weedy inlets, sandy shallows, rock shelf, gravel, etc.) showed that each supported a...
Neuronal recruitment in the black-capped chickadee (Poecile atricapillus) hippocampus occurs at a higher rate in the fall than at other times of the year. As a means of determining whether this increase in recruitment results from greater neuron...
Nocturnal flight exposes insects to selection pressures that include reduced light and the hunting behavior of insectivorous bats. Using a phylogenetically based selection of wild moths collected from a Nearctic site, we report that earless species fly less throughout the...
Parental care can be costly to a parent in terms of both time and energy invested in the young. In species with cuckoldry or brood parasitism not all of the young under a parent's care are necessarily offspring. In such...
Increased mortality in the presence of stress may result from stress-reduced availability of energy for immune function, coupled with the presence of pathogens or parasites. We tested the hypothesis that stress reduces antiparasite responses of damselflies Ischnuraverticalis (Hagen) to...
Female Black-capped Chickadees (Poecile atricapillus) solicit extrapair copulations (EPCs) from neighboring high-ranked males, and these EPCs result in extrapair young. Females might choose to locate their nests near the territory boundaries of attractive males to facilitate access to...
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...
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...
Patterns of overwinter mortality in the sexually dimorphic red-winged blackbird (Agelaius phoeniceus)were examined to test the predictions of the sexual-selection hypothesis that male size is limited by directional selection favoring small males and that female size is maintained by stabilizing...
We conclude that the age-correlated differences in infestation of dragonflies by mites could be a valuable method for determining relative age within odonate populations.
We demonstrate that the probability that an individual nestling received food was related to several indices of begging. When we experimentally prevented parents from feeding part of their brood, both the intensity of begging and the number of feedings subsequently...
One of the costs to female birds of mating polygynously is having to share the parental care provided by their mate. Nest defence, however, is one form of paternal care that females mated to the same male should be able...
The size and age distributions of Acer saccharum Marsh. seedlings were studied in a mature hardwood forest in southeastern Ontario between 26 June and 26 September 1986. Ninety‐one percent of the seedlings surveyed were produced in 1984 which was a mast...
Several aspects of nest defence behavior were investigated in song sparrows (Melospiza melodia) in eastern Ontario. Two independent tests were made of the hypothesis that the increase in nest defence observed through a nesting attempt is due to...
We examined 10 characteristics of natural cavities and their influence on reproductive success of Tree Swallows (Tachycineta bicolor) nesting in dead trees in beaver ponds. Large ranges were found for entrance height and area, cavity volume, and nearness...
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...
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...
Cluster analysis of hybridizing Lepomis gibbosus (pumpkinseedsl and L. macrochirus (bluegills) collected in Lake Opinicon, Ontario, using data on 20 morphological characters in 108 specimens, revealed three groups, the two parental species and a group of hybrids, all of which...
Acetylene reduction by bacteria in the rhizosphere of Glycerin borealis and Typllrc sp. was studied under anaerobic and aerobic conditions. Under anaerobic conditions, when roots and rhizomes were incubated with rhizosphere sediments at 25'C without glucose, acetylene reduction to ethylene...
In the course of the rearing program it was found that certain species either prefer food plants other than those recorded in the literature or refuse those which are commonly thought to be preferred.
