Thesis (M.S.)--University of Maine, 1987. / Includes vita. Includes bibliographical references (leaf 54). Available also in electronic format on the Internet.

Thesis (M.S.)--Ohio State University, 1965. / OSU's c.3 is a photocopy. Available online via OhioLINK's ETD Center

The effects of corticosterone, cortisol, aldosterone, oxytocin and vasopressin on the renal excretory pattern of the water-loaded domestic duck (Anas platyrhynchos) were examined. When compared with the results obtained from mammalian studies, the excretory pattern differed little with respect to water and sodium. The domestic duck showed high levels of potassium excretion. It is suggested that the function of the potassium secretory mechanism in the distal tubule may be predominant in this species. / Science, Faculty of / Zoology, Department of / Graduate

The Sea-Ducks (tribes Mergini and Somateriini), stiff-tailed ducks (tribe Oxyurini) and the pochards and scaups (tribe Aythyini), all of which are diving ducks with a lobed hallux, are considered to be polyphyletic, but their systematic affinities are extremely uncertain. Until 1958, the Sea-Ducks were considered as one tribe but have now been split into two unrelated groups, on the basis of differences in tracheal and plumage characters of the eiders which closely resemble those of the surface-feeding ducks (Anatini). This study, made in British Columbia and Alaska, was begun in 1955 and continued through 1958. It was planned to describe the display characters of Sea-Ducks and to use these to suggest systematic relationships among the eight genera in which the twenty species are grouped. The behaviour of six species (Melanitta and Bucephala) was studied in some detail, and observations were made also on three other species (the monotypic Clangula and Hlstrionlcus, and on Somaterla spectabilis). Published information was also utilised (particularly that on Mergus albellus, M. serrator and Somateria mollissima), so as to make the study comparative for the whole group. In ducks the pre-copulatory displays of male and female, and the general displays peculiar to the female, are highly conservative. They may be used as taxonomic characters at the generic and tribal levels of classification. The general "courtship" characters of the male are of little value at any taxonomic level, except within a large genus (e.g. Anas). This is because signal characters may evolve from basic non-social or agonistic behaviour independently in related lines, and because of convergence (at the generic or tribal level) in isolating mechanisms such as male plumage and display characters. In female and pre-copulatory behaviour characteristics, both Somateriini and Mergini are shown to be quite distinct from the Anatini. In female courtship behaviour Somateria resembles some of the Aythyini, and Melanitta. In female behaviour Clangula resembles Melanitta and both are distinct from Bucephala. Mergus has been considered closely related to Bucephala for various reasons. There are striking (? convergent) similarities in some of the displays of the male of M.merganser and M.serrator with displays of B. clangula, but further study is required of the behaviour of Mergus before ethological evidence linking the two genera is acceptable. B. albeola and M.albellus have been supposed to be links between the two genera, but they have little similarity, at least in the behaviour of the male. The pre-copulatory behaviour of B. albeola is more like that of Melanitta than the goldeneyes (B. islandica and B.clangula) in which it is highly developed. The behaviour of the female of B. albeola is unlike either the goldeneyes or Melanitta. B. albeola probably deserves generic distinction from the goldeneyes, although in nesting behaviour, territoriality, diving and agonistic behaviour it resembles them. On the behavioural evidence the Mergini appear to consist of at least two unrelated lines (Melanitta—Clangula and Bucephala—Mergus). The position of Histrionicus is not clarified. On the pattern of its downy young it seems close to Clangula, but Humphrey noted that it had an eider-type tracheal bulla. The male of both Histrionicus and Clangula has a paucity of visual displays which is accompanied by rather greater vocalisation than in other Sea-Ducks. It is suggested that paucity of visual displays is an indication of isolation from related groups, due to ancestral divergence, so that the generic rankings of Clangula and Histrionicus should perhaps stand. / Science, Faculty of / Zoology, Department of / Graduate

The purpose of this investigation was to determine whether or not the adrenocortical steroids influence the activity of the avian supra-orbital gland. In the intact saline loaded duck (Anas platyrhynchus), a diphasic excretory pattern was apparent, as an urinary diuresis was followed by activation of the supra-orbital glands. Variations in the circulating levels of adrenocortical steroids resulted in qualitative and quantitative changes in both phases of this response. Injection of exogenous, cortisol, cortexone and aldosterone caused an initial increase in the rate of nasal discharge and a consequent increase in the total output of Na⁺ and K⁺. Conditions of selective adrenocortical activity, i.e., subtotal adrenalectomy, severely impaired the extra-renal response while total adrenalectomy completely obliterated the response to an osmotic stimulus. The activity of the supra-orbital gland in the totally adrenalectomized duck was restored after treatment with cortisol. The renal phase in ducks treated with adrenocortical steroids was modified when compared to the control response. Administration of cortisol prior to saline loading resulted in a significantly lower total output of sodium although the volume of urine excreted did not differ from the control value. Treatment with aldosterone resulted in a significantly lower renal output of both Na⁺ and K⁺ as well as a decrease in urine volume. Cortexone and ACTH showed the control renal pattern of excretion. Unilateral adrenalectomy caused no apparent change in the renal excretory pattern whilst total adrenalectomy caused a significant increase in the total volume of urine excreted as well as on increase in the total output of Na⁺ and K⁺. Totally adrenalectomized birds maintained on cortisol reverted to a normal excretory pattern. The influence of adrenocortical steroids on the control of the avian supra-orbital gland is discussed. It can be said with certainty that adrenocortical steroids influence the activity of the supra-orbital gland of the Domestic Duck (Anas platyrhynchus). Furthermore, cortisol administered to the adrenalectomized animal reactivates the gland suggesting that a glucocorticoid is essential for its function. / Science, Faculty of / Zoology, Department of / Graduate

Acid-base balance in plasma was studied in forcibly submerged Pekin ducks (Anas platyrhynchos). All important variables determining acid-base balance (arterial CO₂ tension (PαCO₂) strong ion difference ([SID]) and total protein content which approximates total weak acid concentration in plasma) were measured. During forced submergence PαCO₂ increased and pHa steadily decreased with time. There was also an increase in [lactate⁻], which was accompanied by an increase of equal magnitude in [Na⁺]. There were no significant changes in the concentrations of other strong ions (K⁺, Ca²⁺, Mg²⁺ and Cl⁻). Strong ion difference did not change during the first two minutes of submergence, but there was about a 4 mequiv/L increase by the end of the four-minute dive. Theoretically an increase in [SID] should cause plasma to be alkaline, but since plasma became progressively acidic, this condition can only be due to the increase in PαCO₂. During recovery from dives, the plasma remained as acidic one minute after emersion as at the end of the dives. On the other hand, arterial pH slowly increased towards the pre-dive level during recovery. Arterial CO₂ tension decreased much more rapidly and was already at or below the pre-dive level one minute after emersion. Therefore, PαCO₂ could no longer affect plasma pH. There was, however, a great increase in [lactate-] in the first minute of recovery. Although [Na⁺] and [K⁺] were elevated, from pre-dive values after the four minute dive, the increase in [lactate⁻] resulted in a marked reduction in [SID]. Since there was no change in the total plasma protein content, the acidic condition observed in recovery could only be due to decreased [SID]. Breathing 0₂ before diving prevented circulatory adjustments and pH returned to pre-dive levels one minute after emersion, confirming that the acidic condition observed in recovery is a consequence of the lactate produced in the hypoperfused tissues during submergence. / Science, Faculty of / Zoology, Department of / Graduate

This study was conducted to evaluate waterfowl harvests on the Delta Marsh, Manitoba, under a variety of options utilizing a modified predator-prey model. The study involved monitoring of ducks and hunters to examine key components of waterfowl mortality. Seven hypotheses were formulated involving the relationships between duck vulnerability by species and hunter effort, factors determining effective bag size, hunter effort, effects of weather on kill, and whether or not hunters are selective. Aerial surveys and experimental hunts were conducted and kill statistics gathered on the Pasquia and Delta Marshes in Manitoba to evaluate predictions from the hypotheses. The analysis of field data revealed that duck vulnerability is negatively proportional to hunting effort and that ducks are most wary when hunter effort is greatest. Hunters were afield in largest numbers during periods of high duck density. Hunters did not shoot selectively and crippling losses approximated one-third of the birds shot. Weather had little influence on the kill; bird population size and hunter effort were more important determinants of hunter success. Distribution patterns of ducks were clumped relative to hunting areas, and the probability of mortality for an individual duck was observed to decrease with increasing flock size. Handling time per bird downed did not limit achieved bag size whereas time between encounters was found to be independent of population size and resulted in a non-linear, kill-density relationship. Field results were incorporated into the predator-prey model and management schemes involving population size, hunter effort, and season length were evaluated. Simulation results revealed that Mallard and Lesser Scaup harvest are not greatly affected by increased hunter effort and that season length and population size strongly influence harvest. Shortened seasons are recommended if kill reductions are desired for Mallard. Lesser Scaup require no special regulations whereas Canvasbacks require short seasons (less than 2 weeks) during times when populations exceed 5000. The predator-prey model is recommended for in-depth analysis of local regulations whereas multi-variate statistical models may be more useful in forecasting yields on a regional level. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

No description available.

No description available.