Bluegill sunfish (Lepomis macrochirus), exposed to a 22-day subchronic exposure of pentachlorophenol at concentrations of approximately 20 and 75% of the 96-h median lethal concentration (96 h LC50), showed significant reductions in food conversion efficiency measured during the last 10...
Red-winged Blackbirds have bright red epaulets, the size of which appears to be associated with aspects of social dominance and parental behavior. Red-band effects were experimented with to see whether they effected territories, ect.
The term adoption is widely used to describe care of young by unrelated adults. However, only a few studies have quantified the amount of care provided when replacement males feed young, and the effects of this care. Twenty-five male eastern...
This paper uses three different methods to describe the morphology of bluegill of a common random genetic background reared from larvae in four experimental ponds, the fish of each pond differing in average growth rate.
Fledgling sex ratios biased in favor of the less costly sex in sexually dimorphic birds have been used as evidence in support of Fisher's theory that parents should invest equally in sons and daughters. However, such biased sex ratios are...
Several studies concerned with mate choice, reproductive performance, and life history strategies have been conducted with secondary cavity nesting birds breeding in nest boxes. Although the need for comparative studies has been recognized, populations breeding in nest boxes often have...
Although bat detectors are used with increasing frequency for the identification of bats in the field (Aldridge and Rautenbach, 1987; Crome and Richards, 1988), only one study comparing performance of different models has been published (Downes, 1982). Some bat detectors...
We examined trap bias relative to body condition, age, and sex using data collected from Brown-headed Cowbirds (Molothrus ater) decoy trapped during the 1987 and 1988 breeding seasons. A condition bias was evident, as decoy-trapped birds were in poor condition...
Black-capped Chickadee (Parus atricapillus) song consists of two notes, termed fee and bee. Frequency measures at three key points (at the start and end of fee, and at the start of bee) were obtained from the...
Twenty-seven species of water mites of the genus Arrenurus were compared with respect to allocation of reproductive effort. Clutch volume was positively correlated to female volume, female volume was positively correlated with clutch size and with larval volume, while clutch...
Phenotypic plasticity and genotypic variation were studied in Agropyron repens L. (Beauv.) collected from populations in two grassland communities which differed in the length of time since the last major disturbance. Twenty genotypes were collected from each population. Each genotype...
The auditory characteristics of two populations (laboratory reared and wild) of North American gypsy moths (Lymantriidae: Lymantria dispar L.) were sampled and the neurally derived thresholds of wild males and females to frequencies from 5 to 150 kHz compared. The...
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...
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...
We compared aspects of eastern kingbird (Tyrannus tyrannus) breeding biology between lakeshore and upland habitats in eastern Ontario. Nests were more closely spaced and eggs were laid earlier at the lakeshore than in the uplands. Within the lakeshore...
in situ cylindrical porewater sampler, with interval stackers and a nondegradable membrane, is described. Both horizontal and vertical gradients of dissolved constituents in porewater can be assessed. Sampling at 4-cm intervals within Myriophyllum spicatum root zones showed that steep depletion...
Radio transmitters for implantation in snakes were designed to provide transmitter life in excess of one year. This was achieved by using a 290 mAh, 3.5 V Lithium-Thionyl Chloride battery and a 2 stage transmitter with a thermistor in the...
The effect of phytophagous beetles on plant succession in an old—field community in southeastern Ontario was investigated over a 5—yr period. An experimental comparison of insecticide treated and untreated plots indicates that grazing by Trirhabda spp. on the goldenrod Solidago...
Female Red-winged Blackbirds were observed to interact aggressively with conspecific females during the breeding season. Redwing females attempted to repel intruding females through the use of vocalizations, displays, and aggressive chases. Mapped positions of marked individuals indicated that female Red-winged...
The intensity of nest-defence aggression by female redwinged black birds (Agelaius phoeniceus) with eggs decreased late in the breeding season, while aggression at this time increased amongst females defending broods. High predation pressure late in the breeding season decreased the...
Male bluegill sunfish are shown to have two alternative mating strategies: cuckoldry or parental care. Cuckolder males first mature at age 2. They follow a developmental sequence of sneaking and then mimicking female behavior to deceptively gain access to spawnings...
We used neurophysiological analyses to determine that arctiid moths which emerge, as adults, during the spring possess tympanic organs responsive to ultrasonic stimuli similar to the echolocation signals of bats. These species, however, do not express another form of bat-directed...
The rim circling (RC), and aggressive habituation of nesting bluegills were studied in natural colonies during the six days of the reproductive period following spawning. To examine the stimulus specificity of aggressive habituation, selected test individuals and four neighbors were...
A total of twenty-six allozyme loci were assayed in six crayfish species. Estimated mean heterozygosity was low (5.5 percent) for all species in comparison with the invertebrate average. The specific values, however, ranged from 2.9 percent to 8.3 percent. These...
Seventeen of the 24 species of Nearctic Arctiidae which we examined produced sounds under a variety of tactile and acoustic stimuli. Seven of 14 sound-producing species tested emitted their sounds in response to the hunting cries of insectivorous bats or...
An electronic system for monitoring activity of some echolocating bats in the field is described. An ultrasonic receiver is used to detect the bat cries. Audio-frequency signals from the receiver are processed and converted by the system to characteristic marks...
Nocturnal activity of bats over different environments may be measured using a heterodyning device which converts the ultrasonic echolocating cries to audible "clicks." Preliminary results obtained by this method indicate that bats are more active over lakes than over streams...
The sediments deposited beneath the thermocline in certain lakes are finely banded with alternating dark and light bands. Most workers have assumed this banding to be an annual phenomenon, with the light bands representing summer deposits and the dark bands...
A modification of the Livingstone piston sampler is described. The sampler employs the piston feature of the Livingstone device in conjunction with the rod and locking mechanism of the Davis borer. The sampler is used in different ways for loose...
