Although host parasite interactions can affect the ecology and distribution of species, virtually nothing is known about range-wide variation in haematozoan levels in North American birds. We investigated haematozoan prevalence and parasitemia in 112 adult male cerulean warblers (Dendroica...
Male bluegill sunfish (Lepomis macrochirus) exhibit alternative life histories: some males (parentals) delay maturation for up to 7 yr, then build nests, court females, and care for the eggs and fry, whereas other males (cuckolders) mature precociously, attempt to...
Hook size is an important consideration in the use of circle hooks as a conservation tool for minimizing the injury and mortality of marine fishes, but little is known about the role of hook size in the performance of hooks...
A fundamental assumption of sexual selection theory is that the reproductive advantage of large size is balanced by a survival disadvantage. Previous studies of the sexually size-dimorphic red-winged blackbird (Agelaius phoeniceus) have indicated that the largest adult males...
Habitat loss and large-scale climate phenomena are widely implicated as causing decline in animal populations. I examined how both factors contributed to a precipitous decline in an Ontario red-winged blackbird (Agelaius phoeniceus) population using 16 years of data...
In socially monogamous species, extra-pair paternity has the potential to increase the variance in male reproductive success, thereby affecting the opportunity for sexual selection on male extravagant ornamentation. In the European barn swallow (Hirundo rustica rustica), the tail...
Male bluegill displays one of two life history tactics. Some males (termed “parentals”) delay reproduction until ca. 7 years of age, at which time they build nests and actively courts females. Others mature precociously (sneakers) and obtain fertilizations by cuckolding...
Bergmann's rule, the tendency for body size to be positively correlated with latitude, is widely accepted but the mechanisms behind the patterns are still debated. Bergmann's originally conceived mechanism was based on heat conservation; other proposed mechanisms invoke phylogeny, migration...
Defence against parasites and pathogens can be essential, yet not all hosts respond similarly to parasitic challenge. Environmental conditions are thought to explain variation in host responses to parasites.
Lestes forcipatus damselflies emerging later in the season have shown higher...
Understanding the trade‐off females make between offspring size and number requires knowing how neonatal size, and traits associated with size, affect survival. We studied neonatal survival in the northern watersnake Nerodia sipedon in outdoor enclosures with artificial hibernation sites. From...
Cerulean warblers (Dendroica cerulea) have experienced significant declines across their breeding range and presently exist in disjunct populations, largely because of extensive loss and fragmentation of their breeding and wintering habitat. Despite this overall decline, a recent north-eastern...
Although most of the studies on the evolution of mimicry and warning signals in insects have considered birds as the main predators, predation by other taxonomic groups, such as insects, may far exceed avian predation at some localities. However, few...
The quantitative and qualitative variability in floral scent of 98 specimens of the dioecious species Silene latifolia belonging to 15 European and 19 North American populations was determined. Floral scent was collected from single flowers using dynamic headspace methods, and...
Secondary succession was documented throughout a long-term study of two abandoned hay fields in south-eastern Ontario. In one field (Field 1), eighteen plots (measuring 100 m2) were established. Nine of these plots were ploughed to bare ground and...
We observed the responses of the AN2 interneuron in the Pacific field cricket, Teleogryllus oceanicus, a cell implicated in eliciting avoidance flight away from bats, to acoustic stimuli representing the echolocation calls of bats as well as field recordings...
Hosts often differ in their degree of parasitism and their expression of resistance. Yet very little is known about how the availability (and allocation) of resources to parasites at pre-infective stages influences their success in initiating parasitism, or in inducing...
We studied the efficiency and effects of the multiple sensory cues of tiger moths on echolocating bats. We used the northern long-eared bat, Myotis septentrionalis, a purported moth specialist that takes surface-bound prey (gleaning) and airborne prey (aerial hawking)...
The relationship between gregariousness and warning signals in defended species has been the subject of much debate. While previous researchers have found that predators learn to avoid conspicuous unpalatable prey faster when they are in aggregations, they have not presented...
The risk of extinction of populations has not previously been empirically related to parameters characterizing their population dynamics. To analyze this relationship, we simulated how the distribution of population dynamical characters changed as a function of time, in both the...
The successful use of stable isotopes to track migratory animals between different seasons of the annual cycle depends, in part, on the turnover rate of isotopes in sample tissue. We examined whether stable‐carbon isotopes in the blood of a long‐distance...
Knowledge of animal spatial ecology is essential for the design and siting of proposed aquatic protected areas (APAs), as well as the assessment and monitoring of existing ones. Acoustic telemetry is one of the primary tools for the assessment of...
Although the evasive flight of eared moths to attacking bats has received much attention in the literature, no studies have been made of the potential costs for this behaviour. We examined the fate of moths that land upon the surface...
Evidence is reported for size‐dependent (allometric) gender allocation in the monoecious, wind‐pollinated annual Ambrosia artemissifolia. Consistent with established theory, the pattern of allometry displayed adaptive plasticity, depending on the environmental cause of variation in plant size. Plant size gradients...
The sub‐lethal effects of catch‐and‐release angling have been poorly studied because of the difficulties in monitoring physiological parameters in free‐swimming fish. Laboratory studies provide the opportunity to examine sub‐lethal effects in controlled environments, but do not incorporate site‐specific characteristics. In...
Remote measurement of the physiology, behaviour and energetic status of free-living animals is made possible by a variety of techniques that we refer to collectively as ‘biotelemetry’. This set of tools ranges from transmitters that send their signals to receivers...
The two-note fee-bee song of male black-capped chickadees functions during the dawn chorus, in part, as a sexual signal across large distances. How song structure might encode information about male quality, however, remains unclear. We studied the availability of cues...
Nonequilibrium conditions due to either allopatry followed by secondary contact or recent range expansion can confound measurements of gene flow among populations in previously glaciated regions. We determined the scale at which gene flow can be estimated among breeding aggregations...
Whether the Pleistocene has had a disproportionate impact on the recent diversification of temperate species, or played a lesser role in a more protracted process, has been a prominent evolutionary debate for the past decade. We used cytochromeb...
To determine the consequences of dispersal and gene flow for temporary pond water mites (Hydrachnida), we compared distributional, genetic and morphological characters in the closely related species Arrenurus angustilimbatus and A. rufopyriformis. The former has larvae that parasitise and disperse...
Within a network of communicating individuals, animals may gather information about the relative quality of conspecics by eavesdropping on their signalling interactions. For territorial male songbirds, eavesdropping may be a low-cost, low-risk method for assessing the relative quality of the...
We examined the effects of song tutoring on adult song preferences, volume of song‐control brain regions, and activity of auditory brain regions in female house finches (Carpodacus mexicanus). Hand‐reared females were tutored with local songs, foreign songs, or...
Crown average canopy trees during an ice storm in January 1998 in an eastern Ontario woodland average canopy openness (per cent open sky) to 23.6% from 8.8% in the previous growing season. The resulting effects of increased sugar penetration ( Acer...
Rock bass (Ambloplites rupestris) are a widespread centrarchid species with both riverine and lacustrine populations. After precipitation events, rivers often carry elevated silt loads, where as lakes generally remain free from suspended silt and sediment. To examine the...
Inbreeding is a major component of the mating system in populations of many plants and animals, particularly hermaphroditic species. In flowering plants, inbreeding can occur through self‐pollination within flowers (autogamy), self‐pollination between flowers on the same plant (geitonogamy), or cross‐pollination...
Most moths use ears solely to detect the echolocation calls of hunting, insectivorous bats and evoke evasive flight manoeuvres. This singularity of purpose predicts that this sensory behavioural network will regress if the selective force that originally maintained it is...
Some, but not all, jurisdictions in North America have regulations in place designed to protect nesting male largemouth bass Micropterus salmoides and smallmouth bass M. dolomieu from angling. The underlying assumption that brood‐guarding males are particularly vulnerable to angling, however...
Animals often exhibit territorial spatial structure in their breeding habitat. This clustering behavior is not well understood. We reviewed eight hypotheses for clustering and tested two ecological hypotheses for the formation of dense, territorial clusters in the Least Flycatcher (...
Males of many species are characterized by alternative mating tactics. In bluegill sunfish (Lepomis macrochirus), some males delay maturation and become “parentals” while other males mature precociously and become “cuckolders.” Parentals use an overt, territorial mating tactic, defending...
We assessed the effect of radiotelemetry on the growth, reproduction, and survival of black ratsnakes (Elaphe obsoleta) using data from a 6‐year study. Transmitters were surgically implanted for more than one year and were <2.5% of the snakes'...
The Cerulean Warbler (Dendroica cerulea) tops many lists of species of conservation concern because of severe population declines and habitat loss. Here we present the first robust estimates of annual survival and population growth rates for this species...
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...
During vocal contests, animals alter both the timing and the patterning of responses to their opponents. Time-specific responses (such as overlapping an opponent's song) and pattern-specific responses (such as matching the type of an opponent's song) may reveal information about...
In sexually promiscuous animals, females may benefit by nesting close to the edge of their partner's territory to facilitate extrapair copulations. In the present study, we describe the extrapair mating system of black-capped chickadees, Poecile atricapillus, and test whether...
Auditory sensitivities and ultrasound avoidance behaviour of two exclusively diurnal moths were examined to test the prediction that total isolation from the predatory effects of echolocating bats will result in the regression of these sensory systems and/or the defences they...
Nest-site selection is the only behaviour that can be considered parental care in most oviparous reptiles because eggs are abandoned after laying and because incubation conditions resulting from nest-site selection can have profound effects on offspring. During a 7-year study...
In the current study, we simulated different components of a live‐release angling tournament (angling, live‐well confinement, and weigh‐in) to determine the relative physiological significance of these tournament components for largemouth bass Micropterus salmoides. Our results indicated that depletions of...
Single-species habitat management strategies are often undertaken without explicit consideration of their effects on the larger community. Here we explore the potential effects of managing eastern Ontario deciduous forests for the Cerulean Warbler (Dendroica cerulea) by examining its...
We examined whether differences among hosts in timing of emergence of phenotypic attributes might affect their probability of return to an emergence pond, and hence success of mites.
We examined the relationship between non-polar lipid density, parasite density and paternity of male bluegill sunfish, Lepomis macrochirus, and four condition factors: (1) Fulton’s condition factor, K; (2) the relative condition factor, Kn; (3) the relative mass index, Wr; and...
Toward the end of the breeding season, migratory songbirds face crucial tradeoffs between the timing of reproduction, molt, and migration. Using stable hydrogen isotopes, we show that male American redstarts investing in high levels of reproduction late in the season...
Flowering plants often exhibit declining investment in gametes, seeds, and floral organs among sequentially blooming flowers within inflorescences. However, few experimental studies have determined the relative importance of proximate underlying causes such as architectural constraints or resource competition among flowers...
Although in birds and mammals sex‐specific differences in organismal performance and physiology are well documented, comparatively little is known about the influence of sex or reproductive status on fish performance or metabolism.
In this study, the resting cardiovascular performance of...
Low frequency of reproduction among iteroparous organisms is most often observed among female ectothermic vertebrates and is thought to be a strategy used to defer reproductive costs. We assessed reproductive costs of male water snakes (Nerodia sipedon) to...
Colonial breeding can evolve in response to benefits afforded by clumped individuals, such as reduced predation and increased ease of assessing potential mates. However, colonial breeding can also impose costs such as increased disease transmission or increased cuckoldry. Here, we...
An important problem in understanding the evolution of parasite host range is determining the extent to which parasite fitness varies among host species and the factors affecting that fitness variation. We present a detailed investigation on the patterns of host...
Under sperm competition, a male’s fertilization success depends largely on the ejaculate characteristics of competing males. Theoretical models predict that, in external fertilizers, increased risk of sperm competition should result in selection for increased sperm swimming speed. To test this...
