Mark-recapture Program Research Articles

Accuracy of Using Scales and Cleithra for Aging Northern Pike from an Oligotrophic Ontario Lake

We examined the validity (accuracy and precision) of using scales and cleithra to assess the structure of the small population of northern pike Esox lucius (N = 220–270 fish age 3 or older) found in Squeers Lake, Ontario (48°31'N, 90°33'W). The high percent frequency of agreement, low index of average error, and low index of precision indicate that both scales and cleithra are equally suitable tissues for assigning age structure to Squeers Lake northern pike. An examination of the accuracy of age estimates through the use of oxytetracycline (OTC) labeling and mark–recapture of fish confirmed that marks identified on both tissues were in fact annuli. Cleithra, however, yielded more accurate results for northern pike older than age 10. Future northern pike age-assessment studies require further mark–recapture and OTC-labeling programs, particularly when precision levels exceed 5%. The collection of this additional data from any ongoing mark–recapture program would not only quickly validate the population's age structure, but would also ensure the accuracy of any future comparison based on age composition.

Effects of forest fragmentation on amazonian understory bird communities

SUMMARYData form an intensive mist-netting mark-recapture program in the central Amazon demostrate significant changes in the undesrtory avian community in isolate patches of 1 and 10 ha of terra firme forest. Following isolation, capture rates increase significantly as birds fleeing the felled forest entered the. newly formed forest fragments. Movement to and from the reserve is restricted, as witnessed by an increase in recapture percentages following isolation. Species of birds that axe. obligate army ant followers disappeared at the time the surrounding habitat was removed from 1 - and 10 - ha areas. The complex mixed-species insectivorous flocks typical of Amazonian forests deteriorated within 2 years of isolation of 1 - and 10 - ha forest fragments. Several species of mid-story insectivores changed their foraging behavior after isolation of small forest reserves.

A Population Dynamics Model of Black Bears in Eastcentral Ontario

A population model was developed to estimate demographic parameters and abundance of a black bear (Ursus americanus) population in eastcentral Ontario, using data from a 12-year mark-recapture program. The model enables the separation of natural and hunting mortality and allows for immigration to the study area. Parameter fitting was done by a nonlinear least-squares criterion. Abundance estimates using the 0-truncated Poisson, Petersen, and Jolly-Seber procedures allowed comparison of the different methods. The population growth rate was estimated as 2.9%/year for the female segment. Age-specific reproductive value was calculated, and its significance for black bear conservation is discussed. J. WILDL. MANAGE. 50(4):602-612 The black bear is one of Ontario's most familiar and widely distributed large mammals. Traditionally it was regarded as a predator and a nuisance, and a provincial bounty was paid from 1942 to 1961. In 1961, the species was recognized as a valuable wildlife resource with removal of the bounty and elevation to game animal status (Clarke 1961). During recent years, increased hunter pressure in many areas and invasion of black bear habitat by nonconsumptive users intensified the need for information about population densities and behavior. Although important studies of black bear demography have been conducted in a variety of habitats (Jonkel and Cowan 1971, Poelker and Hartwell 1973, Rogers 1977, Beecham 1980, Lindzey and Meslow 1980, Young and Ruff 1982), none have been carried out in the conifer-deciduous forests of eastern Canada. This paper presents the results of an extensive mark-recapture program carried out in eastcentral Ontario from 1969 to 1980. Objectives of the study were to: (1) estimate population abundance; (2) estimate age-specific natural mortality; (3) estimate immigration into the study area; and (4) use this information, together with reproductive data obtained during the study, to estimate the intrinsic growth rate of the population and the age-specific reproductive value of female bears. This project was supported in part by the Nat. Sci. and Eng. Res. Counc. Can. under Grant A7775.

Pollen flow in Psiguria warscewiczii: a comparison of Heliconius butterflies and hummingbirds.

Pollen dispersal by male and female Heliconius butterflies and hermit hummingbirds was examined in a natural population of the tropical vine Psiguria warscewiczii. Fluorescent dyes were used to track flowers visited by individual pollinators. Mean distance of pollen dispersal was significantly higher by males than by female Heliconius. Butterflies dispersed pollen greater distances than did hummingbirds. There were no significant differences in dispersal distance among species of Heliconius. The number of flowers or plants to which dye was dispersed was greater for Heliconius than for hummingbirds.The home range behavior and site specificity exhibited by Heliconius, together with the preference by most Heliconius species in the study site for Psiguria led us to examine the relationship between the butterflies' home range and its daily foraging among Psiguria. A Heliconius mark-recapture program was conducted simultaneously with the dye program. This study showed that individual butterflies, for which extensive recaptures were made, visited an area of Psiguria plants on any one day that corresponded to the area in which those butterflies were caught or observed. The area over which a butterfly moved was termed its home range; within home ranges relative movement by butterflies was estimated as the mean distance between sequential captures. This estimate differed significantly among species of Heliconius; males of all species moving greater distances than females.

The ecology and social behaviour of the Neotropical butterfly Heliconius xanthocles Bates in Colombia

The mimicry, population ecology1, adult behaviour and life cycle of Heliconius xanthocles were studied at two sites in Colombian tropical forest. The results were compared with the known biology of other Heliconius species. H. xanthocles is probably unpalatable and is a Mullerian comimic of some other species. In the Amazon basin H. xanthocles belongs to the ‘dennis ray’ mimicry ring of the Heliconiini, which includes Eueides tales, H. bumeyi, H. elevatus, H. melpomene and H. erato. In the Rio Negro valley, where the latter species either do not exist or have different mimetic allegiances, the ‘clennis-ray’ pattern of H. xanthocles breaks down. The adults are pollen-feeders, like other Heliconius. but they also visit other food sources such as bird droppings. During a mark-recapture programme in the Rio Negro, adults were found to be almost entirely restricted to small areas near their foodplant Passiflorapraeacuta. Females were rarer than males, but this was probably due to a behavioural difference between the sexes. The males had a Fisher-Ford survival rate of 0.95 per day and a life expectancy of 19 days. Population size estimates of males were between 11 and 17 individuals. These estimates are lower than, but comparable to those for other Heliconius. Males as well as females visit the larval toodplant, and an adult male was observed hovering over a small group of larvae. The females lav batches of 12–41 eggs. The largest batch (41 eggs) was laid cooperatively by two females. The larvae are gregarious feeders on shoot-tips of Passiflora praeacuta. and all lile stages are described for the first time. Predation on the larvae by a bug is described. The pupa has a distinctive morphology unlike that of other Heliconius. The adult population ecology, mimicry and larval behaviour are discussed.