Gordon F. Bennett

Bio: Gordon F. Bennett is an academic researcher from Memorial University of Newfoundland. The author has contributed to research in topics: Haemoproteus & Leucocytozoon. The author has an hindex of 32, co-authored 171 publications receiving 4147 citations. Previous affiliations of Gordon F. Bennett include St. John's University.

Distribution of the avian hematozoa of North America

Abstract: The literature pertaining to the prevalence of avian hematozoa in North America, north of Mexico, together with unpublished records from the files of the International Reference Centre for Avian Malaria Parasites, have been collated and analyzed with respect to the distribution of parasite genera by region, host family, and vertical stratification of nesting sites. The blood parasites of 57 026 birds of 388 species (representing 55 families) breeding in North America are the basis of this analysis. A total of 21 048 (36.9%) birds harbored one or more species of Haemoproteus (19.5%), Leucocytozoon (17.7%), Trypanosoma (3.9%), Plasmodium (3.8%), microfilariae (3.1%), and Haemogregarina/Lankesterella (0.6%). The continent was arbitrarily divided into seven regions along a topographic basis. Overall hematozoan prevalence varied markedly from region to region, as did the relative frequencies of the different genera. Overall hematozoan prevalence also varied markedly from avian family to family, as did the rela...

Avian Haematozoa: mortality and pathogenicity

Abstract: A review of 5640 articles on avian blood parasites showed that 236 reported mortality or gross pathogenicity in birds, and 89% of them were concerned with mortality in domesticated birds and how to control the blood parasites involved. Only 6% of records concerned birds in zoological gardens; the remainder referred to mortality in wild birds.

Parasite faunas, testosterone and secondary sexual traits in male red-winged blackbirds

Abstract: We examined associations among parasite infections, secondary sexual traits and testosterone in male red-winged blackbirds sampled at the start of the breeding season. Parasites quantified included ectoparasitic lice and mites and endoparasitic blood protozoans, nematodes, trematodes and cestodes. Secondary sexual traits that we quantified included body size, epaulet size and color, song repertoire size and song switching rate, and behavioral responses to male and female models. Overall we found few significant associations between parasites and secondary sexual traits, between secondary sexual traits and testosterone, or between parasites and testosterone. In addition, most parasite taxa appeared to infect birds independently, although the low prevalence (<50%) of many of the parasites meant that our sample sizes were too small to detect weak associations. Our most promising results were obtained for ectoparasitic mites, which tended to occur on birds uninfected with other parasites, on birds with longer epaulets, and on birds with higher levels of testosterone. Epaulet length and testosterone are both probable correlates of dominance in this species. Further research will be required to determine whether there is a causal link between the immunosuppressive effects of testosterone and the mite infections, and between testosterone, epaulet length and male mating success.

Simple techniques for making avian blood smears

Abstract: Simple equipment and techniques for improving the quality of avian blood smears obtained in field surveys are described.

On some ornithophilic blood-sucking diptera in algonquin park, ontario, canada

Abstract: A useful technique was devised for the collection of biting Diptera after they had fed on various birds exposed in dissimilar habitats in Algonquin Park. As a result, the following species of ornit...

Trade‐offs in evolutionary immunology: just what is the cost of immunity?

Abstract: It has become increasingly clear that life-history patterns among the vertebrates have been shaped by the plethora and variety of immunological risks associated with parasitic faunas in their environments. Immunological competence could very well be the most important determinant of life-time reproductive success and fitness for many species. It is generally assumed by evolutionary ecologists that providing immunological defences to minimise such risks to the host is costly in terms of necessitating trade-offs with other nutrient-demanding processes such as growth, reproduction, and thermoregulation. Studies devoted to providing assessments of such costs and how they may force evolutionary trade-offs among life-history characters are few, especially for wild vertebrate species, and their results are widely scattered throughout the literature. In this paper we attempt to review this literature to obtain a better understanding of energetic and nutritional costs for maintaining a normal immune system and examine how costly it might be for a host who is forced to up-regulate its immunological defence mechanisms. The significance of these various costs to ecology and life history trade-offs among the vertebrates is explored. It is concluded that sufficient evidence exists to support the primary assumption that immunological defences are costly to the vertebrate host.

The Physiology of Life History Trade-Offs in Animals

Abstract: ▪ Abstract The functional causes of life history trade-offs have been a topic of interest to evolutionary biologists for over six decades. Our review of life history trade-offs discusses conceptual issues associated with physiological aspects of trade-offs, and it describes recent advances on this topic. We focus on studies of four model systems: wing polymorphic insects, Drosophila, lizards, and birds. The most significant recent advances have been: (a) incorporation of genetics in physiological studies of trade-offs, (b) integration of investigations of nutrient input with nutrient allocation, (c) development of more sophisticated models of resource acquisition and allocation, (d) a shift to more integrated, multidisciplinary studies of intraspecific trade-offs, and (e) the first detailed investigations of the endocrine regulation of life history trade-offs.

Regulation and stability of host-parasite population interactions: II - Destabilizing processes

Abstract: SUMMARY (1) Three categories of biological processes are shown to have a destabilizing influence on the dynamical behaviour of model host-parasite associations: parasite induced reduction in host reproductive potential, parasite reproduction within a host which directly increases parasite population size and time delays in parasite reproduction and transmission. (2) The importance of parasitic species as regulators of host population growth is examined in light of empirical evidence. Data from two particular laboratory studies used to indicate the magnitude of this regulatory influence. Suggestions are made concerning the type of information required from field studies to facilitate critical assessment of theoretical predictions.

The epizootiology and ecological significance of malaria in hawaiian land birds

Abstract: Laboratory and field experiments were conducted on the island of Hawaii from 1977- 1980 in an effort to determine the impact of avian malaria on the forest birds. At 16 study sites from sea level to tree line in mesic and xeric habitat, birds were captured and bled to determine the host and altitudinal distribution of blood parasites. In the laboratory, six bird species were challenged with malarial parasites to measure host susceptibility. Distributions, activity cycles, and transmission po- tentials of malarial parasite vectors were also analyzed. One species of Plasmodium was present from sea level to tree line, concentrated in the mid- elevational ranges in the ecotonal area where vectors and native birds had the greatest overlap. Native forest birds were: (a) more susceptible to malaria than were introduced species; (b) most likely to have malaria during the nonbreeding, wet season; (c) found ranging lower in xeric than in mesic forests; and (d) found to have a lower prevalence of malaria in xeric forests. Temporal as well as elevational differences in prevalence and parasitemia levels of wild birds were apparent throughout the annual cycle, a result of differing host and parasite responses to biotic and abiotic factors. Avian malaria probably did not reach epizootic proportions on Hawaii until after z 1920. However, since that time it has had a negative impact on the population dynamics of the native forest birds and is today a major limiting factor, restricting both abundance and distribution of these species on the island. In response, a number of native bird species have developed immunogenetic and behavioral responses that reduce the impact of the parasite on host populations.

Biology of Blood-Sucking Insects

Abstract: Part 1 The importance of blood-sucking insects. Part 2 The evolution of the blood-sucking habit: prolonged close association with vertebrates morphological pre-adaptation for piercing. Part 3 Feeding preferences of blood-sucking insects: host choice host choice and species complexes. Part 4 Location of the host: the behavioural framework of host location appetitive searching activation and orientation attraction movement between hosts. Part 5 Ingestion of the blood meal: vertebrate haemostasis insect anti-haemostatic factors probing stimulants phagostimulants mouthparts blood intake. Part 6 Managing the blood meal: midgut anatomy the blood meal gonotrophic concordance nutrition host hormones in the blood meal partitioning of resources from the blood meal autogeny. Part 7 Host - insect interactions: insect distribution on the surface of the host morphological specializations for life on the host host immune responses to insect salivary secretions behavioural defences of the host density dependent effects on feeding success. Part 8 Transmission of parasites by blood-sucking insects: transmission routes specificity in vector-parasite relationships origin of vector parasite relationships.