Herons are well known because of their gregarious nesting habits. Like many others of the lower orders of birds they nest together in pure or mixed colonies of many different combinations and under diverse living conditions. The population of different colonies may vary from a few pairs to many thousands of pairs depending upon the nature and extent of the breeding area, the food supply available and the protection afforded either by natural or artificial means. In Utah and adjacent areas of bordering states, many types of heron associations have been studied and reported by ornithological workers. reeding colonies of Treganza Herons, Black Crowned Night Herons and Snowy Herons in pure species associations and mixed communities have been recorded. The tendency of herons to associate with other unrelated orders of birds in nesting situations has also been noted. Such colonies as the Gull-Pelican-Heron associations of the Great Salt Lake Islands and the Heron-Cormorant communities of Cache Valley and Bass Pond Reservoir support this observation. At least eight different communal associations involving herons in the nesting season are known in Utah. The question of the economic status of herons has long been debated among ornithologists and those engaged in the propagation of wild life, especially fish culture. The fish eating propensities of herons are known all over the world. In some regions the birds are condemned as a menace by the sportsman and in other areas they are considered to be his benefactors. Adequate studies have not been published to definitely establish the economic status of this group of birds. It is the purpose of this thesis to contribute to the knowledge of Ornithology by a presentation of the writer's observations and findings on a colony of nesting herons, noting, especially, certain factors influencing the behavior of the birds, their relationships to other animals of the community, economic importance and development of the colony.

The purpose of this work was to study the effects of larval digeneans on the seasonal carbohydrate content and the reproductive biology of Littorina littorea L. at Scalby Rocks, North Yorkshire. Observations on infection with the different species of larvae were also made throughout the survey. There have been many studies on the effects of trematode larvae on the carbohydrate content of their molluscan hosts, but in the main these have been based on histochemical tests and at isolated periods of time (see review by Cheng & Snyder 1962a). It was thought therefore that this aspect of host-parasite relationships afforded itself for further study from a quantitative and seasonal aspect. This work falls into three more or less distinct sections; with an additional one which deals with the topography and ecology of the collecting grounds. The geology of the area is included in this to give a more complete picture of the nature of the coast.

An in vitro bioassay which discriminates between vasopressin and CRF was used in an investigation of the secretion of CRF from the isolated rat hypothalamus incubated in vitro for varying periods of time at different times in the 24-hour cycle. A porcine hypothalamic CRF extract was also tested in the assay and elicited responses similar to those elicited by rat hypothalamic incubation media. During continuous incubations sampled at a series of times (up to 120 minutes) the pattern of CRF secretion is seen to be phasic. The secretion of CRF, when the hypothalamus is incubated for two consecutive 15 minute incubation periods, is shown to be calcium ion-dependent and to display a circadian rhythm with peaks occurring in the afternoon when studied at different times in the 24-hour cycle. From this, the secretion of CRF by the hypothalamus isolated and incubated in vitro is considered not to represent non-specific diffusion or "leakage" of CRF, but a phenomenon of physiological significance which reflects a circadian rhythm in CRF secretion in vivo. The secretion of CRF during two consecutive 15 minute incubations measured systematically at different times of the day shows a circadian rhythm which parallels the peaks and troughs in the circadian rhythm in plasma corticosterone levels, but which shows a phase delay with the increase in hypothalamic CRF content in the afternoon. Reversal of the light/dark cycle results in a reversal of the morning/evening difference in the pattern of CRF secretion during the first 15 minutes of incubation and a concomitant phase-reversal of the circadian rhythm in plasma corticosterone levels. These findings imply that CRF secretion is involved in the. regulation of circadian rhythmicity in plasma corticosterone levels, and that circadian rhythmicity in CRF secretion may be entrained by photoperiodic cues.

This study demonstrates the characteristics of specific receptors for IgG, transferrin and insulin on 11.5 day rat yolk sac endoderm in vitro, using the culture system for the postimplantation rodent embryo as described by New. Coated vesicles are implicated as mediators of a protein transport mechanism, as part of the endocytic process of macromolecular uptake in the yolk sac. Analysis includes immunofluorescent studies, incubation with radiolabelled ligand and immunocyto- chemical localisation of ligand. A peroxidase conjugate was used to localise IgG and colloidal gold was developed as a direct electron microspical membrane receptor probe for IgG and transferrin receptors. Rat IgG and transferrin were found to co-internalise into the same coated vesicle, and were associated with high affinity cell surface receptors. Insulin was found to bind to isolated 9.5 day cells of the egg cylinder and also to isolated 10.5 day, 11.5 day, 12.5 day and full term cells of the yolk sac. The degree of insulin binding to isolated yolk sac cells was comparatively less than the observed binding of insulin to isolated 9.5 day egg cylinder cells, and was found to decrease between days 10.5 and 12.5 of gestation. At 11.5 days the fluid between the yolk sac endoderm and the amnion comprised a mixture of transported serum proteins and synthetic products of the conceptus. Human serum did not support normal growth of rat conceptuses during organogenesis in vitro but human serum proteins were transported by the yolk sac to the yolk sac fluid. The results are discussed in relation to the involvement and formation of coated vesicles and the general importance of protein transport across the inverted yolk sac placenta during organogenesis.

During the last two decades, much public interest and concern has been expressed on the presence of metal ions in the environment and, particularly, in organisms of commercial significance. The concern has arisen because the amounts of such ions has, in local and sometimes general areas , increased to levels which are far higher than 'normal ' background values. The present thesis is concerned with studies on the effects of 3 metals on the brown shrimp, Crangon crangon - a species which is common in the inshore waters of the Yorkshire coast and which has a commercial significance to a number of local fisheries. Of the metals selected for study, cadmium is known to be neither biologically essential nor beneficial to living organisms (Eisler, 1971; Thorpe & Lake, 1974; Bryan, 1976; Pascoe & Mattey, 1977). Consequently, this metal is absent, or present only in trace amounts, in organisms from unpolluted waters. By contrast, copper is an essential element for several living processes, having first been associated with such in studies of blood proteins of Helix pomatia (Harless, 1847 - cited in Severy, 1923). Since then, its functional significance in the oxygen transport of crustacean and molluscan haemocyanins has became well documented (Redmond, 1955). Copper is known also to be an important constituent of certain enzymes such as tyrosinase and cytochrome oxidase (Scott & Major, 1972) and as an activator for certain others (e.g. malate dehydrogenase; Saliba & Krzyz, 1976). Furthermore, copper has been shown to be a necessary component for the successful accomplishment of specific behavioural and physiological phenomena (e.g. the settling and metamorphosis of the oyster, Crassostrea virginica; Prytherch, 1931). Possibly, the ubiquitous distribution of this metal accounts for its wide biological functions in organisms. Zinc also has been found to occur naturally in the tissues of many marine organisms (Bodansky, 1920) and, subsequently, has been shown to be an essential element in many metal-enzymes (Dixon & Webb, 1964). These enzymes include carbonic anhydrase (Keilin & Mann, 1940; Vallee, 1959; Coombs, 1972), alkaline phosphatase (Vallee, 1962; Wolfe, 1970; Coombs, 1972), carboxypeptidase (Vallee, 1962; Coombs, 1972), glutamate dehydrogenase, lactic dehydrogenase, alcohol dehydrogenase (Vallee, 1959) and -D- mannosidase, (Coombs, 1972). Parker (1962) has suggested that the capacity of organisms to concentrate zinc reflects the biological function of this metal. However, as with copper, zinc is usually found in tissues in quantities far in excess of those, required to satisfy the needs of enzymes. Coombs (1972), for example, used data of Vallee & Wacker (1970) to estimate that the oyster, Ostrea edulis used only 0·1% or less of its total zinc content for enzyme purposes. Heavy metals are ·normal constituents of estuarine and marine environments and are usually present in trace amounts. Normally, they reach the sea via rivers following the erosion of rocks. However, with the advent of industrialization, man has contributed to the base levels of metals found in coastal waters. Cairns, Dickson, Sparks & Waller (1970) summarised the industrial attitude as "the production of wastes by industry is not related to the capacity of the ecosystem to absorb and transform these wastes, but rather to market demand." Hence, large quantities of cadmium, copper and zinc, among other metals, have found their way in estuarine and coastal waters, mainly from copper and lead mines (McKee & Wolfe, 1963; Mount & Steven, 1967) and zinc smelting and electroplanting plants (Little & Martin, 1972; Jordan, 1975). By virtue of their physicogeochemical nature, estuaries have the capacity (albeit to a limited extent) to 'detoxify ' heavy metals by altering their biological availability. This is achieved by absorption to particulate material (Krauskopf, 1956) and by precipitation, chelation and sedimentation (Lewis , Whitfield & Ramnarine , 1972; Whitfield & Lewis , 1976; Batley & Gardner, 1978). However, those metal species which remain dissolved in seawater are likely to escape to the open sea (van Bennekom, Gieskes & Tijssen, 1975) and, if present in sufficiently high concentrations, are likely to be directly toxic to the fauna and flora. Many organisms , especially sessile bivalves, can accumulate cadmium, copper and zinc and tolerate high concentrations of these in their tissues without any apparent signs of harm (Brooks & Rumsby, 1965)'. This suggests that such organisms have very efficient methods for preventing these metals from poisoning essential enzyme systems . Other organisms (e .g. Paratya tasmaniensis; Thorpe & Lake, 1974) ,d.o not have the ability to tolerate these metals and are killed by very low concentrations of them. There appear to be few reliable data available on the susceptibility of C. crangon to heavy metals and these studies were undertaken to provide comprehensive data on the toxicity of cadmium, copper and zinc to this species . One widely used and accepted method for the assessment of the effects of pollutants to organisms, is that of toxicity testing (sometimes referred to as 'bioassays '). When death is used as the criterion of response in such studies, the method suffers serious disadvantages in that accuracy is limited because of the wide disparity of individual susceptibility. However, in toxicity studies, it is accepted universally that the most tolerant and the most susceptible individuals in a test group show greater variability of response than individuals near the median of this group. Consequently, the relevant stdies in this thesis are concerned predominantly with the median responses to the test parameters (i.e. the responses of the average individual ). The median lethal concentration (LC50) is the term used generally to describe the concentration at which 50% of the test population are killed Alderdice, 1967; Brown, Jordan & Tiller, 1967; Sprague, 1969; Eisler, 1971). In situations where time is the effect parameter, the median lethal time (LT50) is used to describe 50% mortality value. Concentration and time, however, are here inextricably linked and to maximise their usefulness in comparative studies, LC50 values need to be qualified by a prefixed time component. APHA (1965) has suggested that the time component may be expressed as hours, days or weeks, whichever is convenient in particular circumstances. Similarly, LC50 values should ~e qualified by the concentration of the toxicant used. Median lethal concentrations and LT50 values are determined by graphical means from plots of concentration or time respectively against the percentage mortality of the test population at specific times (LC50) or concentration (LT50). Brown (1973) suggested that 'quantal' bioassays (using concentrations and percentage mortalities) are superior to 'quantitive' bioassays involving exposure times and percentage mortalities. His reasoning is based on the fact that quantal bioassays yield mortality curves which are amenable to mathematical definition and thus enable confidence limits to be given in terms of units of concentration. On the other hand, quantitive bioassay mortality curves represent subjective estimates of effective concentrations. However, when experimental methodology imposes limitations to the design of experiments (e.g. in flow systems which permit but one concentration at a time to be tested) then quantitative methods offer an acceptable alternative. A very important concept in toxicity studies is that of incipient lethal levels (ILL). Sprague (1969) defined an ILL as "that level of the environmental entity beyond which 50% of the population cannot live for an indefinite time." The same concept has been named the 'lethal threshold concentration' (Lloyd & Jordan, 1963) or the 'asymptotic LC50' (Ball, 1967a).

This thesis is concerned with intraspecific competition among damselfly larvae, and on the behaviour and ecology of adults. Pyrrhosoma nymphula (Sulzer) was the subject of the work on adult emergence and behaviour at two ponds in Cheshire, while larvae of Ischnura elegans (van der Linden) were used in laboratory competition studies. An asymmetry was found in the way interference competition acts when small and large larvae of I. elegans were contained together with unlimited prey. Small larvae suffered significantly reduced development rates and size increases at the moult in the presence of large larvae, but similar reductions were not apparent when small larvae were combined with like-instar larvae, or when large larvae were combined with small larvae. In field populations, larvae which have been adversely ..rfected by competition for food or fishing sites ".", be smaller and emerge later than competitively successful larvae. Adult size and seasonal occurrence may have a strong influence on both male and female reproductive success. The emergence of P. nymphula was studied at two adjacent ponds. The emergence from both ponds appeared less well synchronised than might have been expected. There is likely to be a trade-off between the need to emerge around the same time as conspecifics in order to achieve a full rep.roRuctive potential, and the expression of temporal variation arising in part frony~petition. Newly emerged adults from one pond were significantly larger and emerged earlier than those from the other pond. This may have been due to differences in prey availability and distribution, and to temperature differences. A decline in size of newly emerged adults through the season was found at both ponds. During periods of bad weather, numbers of individuals emerging were substantially reduced. Those individuals still attempting emergence presumably did so because of the progression of metamorphosis. Quantification of emergence mortality attributed to different factors was attempted. Mortality was found to be highest after a sudden deterioration in the weather. Mean daily mortality, expressed as a percentage of the total daily emergence, was calculated to be 27.93%. There was no evidence of density-dependent mortality at emergence. Recovery of individuals marked at emergence and when mature was found to be low. For mature adults, this was attributed predominantly to dispersal to nearby water bodies. There was some indication that there was a higher mortality of smaller adults in the immature and reproductive stages of the life-history. Fewer females revisited the ponds than males which led to the estimation of female survivorship being considerably lower than that of males. A large increase in weight of females from emergence to maturity suggests that they may amass clutches of eggs over several days and thus not visit the ponds on every day of their reproductive life. In addition, mortality of females may be higher than that of males as a result of predation during oviposition. For male P. nymphula, size was shown to have no effect on the ~:)Utcomeof territorial disputes.which were settled by a simple residency asymmetry. SIze was also found to be unrelated to the total number of observed matings a male achieved, and the number of days a male spent at the ponds, although the latter may have been obscured by the low return of marked males. The relation of size to longevity could not be studied. Success in mating and in territorial disputes was found to be positively related for resident males. This was probably due to the amount of time spent at the ponds within a day. Late emerging female P. nymphula visiting the ponds later in the season laid smaller clutches of smaller eggs than those arriving early in the season, irrespective of size. Clutch size is likely to be strongly related to the inter-clutch interval and thus the pattern of sunny and cloudy days through the season.

Reconciliation, its nature and the factors driving its evolution within the Primate Order have been the subjects of academic deliberation since the advent of controlled, post-conflict research almost two decades ago. This thesis attempts to draw these thought processes together by using linear regression modelling in a heuristic exercise to tease out the main factors hypothesised as having fuelled the development and refinement of this behaviour through time. It employs the comparative method to control for phylogenetic inertia and uses empirical data from the literature on 21 species of monkeys and apes, from the four major taxonomic groups of non-human primates to test current evolutionary theory. A further hypothesis is also proposed (Social Function Hypothesis) which suggests that reconciliation evolved in response to individuals' need to protect and maintain the function of their social relationships with other group members. An index which reflects the degree of social function found within groups is developed in order to test this hypothesis. The results of this comparative analysis revealed two significant and robust models in which two continuous variables alone (neocortex size and the index of social function), were found to predict the current distribution of reconciliation within the Primate Order. The first model provided compelling evidence in support of the Social Function Hypothesis and for the Good Relationship Hypothesis (Aureli et al., 1989; de Waal, 1986a), in so far as highly functional relationships can be viewed as having a greater intrinsic value than less functional ones. The second model, whilst still supporting the aforementioned hypotheses, appears to undermine the validity of the Minimum Cognitive Capacity Hypothesis (Gallup, 1982). However, alternative interpretations of the results of this model are discussed which prove compatible with the predictions of this hypothesis. The second part of this work explores the characteristics of social networks within a captive group of chimpanzees housed at Chester Zoo (N=19 adults and subadults). It develops a number of measures of relationship function based on social grooming and agonistic support and uses these to assess the quality of different social relationships. According to these measures, valuable relationships within the group were identified as those between: kin; males; males and females; low ranking individuals; high ranking individuals; and medium and high ranking individuals. This information was then used to investigate the nature and expression of direct operational reconciliation using a large sample of isolated dyadic conflicts (N=1220). The overall conciliatory tendency for the species varied with the type and level of analysis, as well as with factors such as the presence of oestrous females, conflict intensity, sex and relationship function. Kinship and relationship value were not found to be reliable predictors of reconciliation frequency. The characteristics of initiators, behavioural specificity of first post-conflict contacts and the factors influencing latencies to these contacts are also discussed. Lastly, the chimpanzee is used as a model species to provide a proximate test of the main theories on the evolution of reconciliation. The results of this piece of research show that, once again, relationship function provides the most accurate predictor of the frequency distribution of reconciliation among dyads in this model species. These findings are discussed in relation to the definition and measurement of reconciliation, the evolution of reconciliation and sociality, and the future of post-conflict research.

The interntion of the prese-r.t study is to invectirate the pro'tlem of clnG) stic reln ti or.shi ps amonc sl"a},es current.ly assigred to tr.e eut far.ti 1;1' Vi rerinae , usinr cl-.arnctere dra'.-«, from the internal and cxterl"al ar.ato!!\y of preeerved mu~euf.1 specimer.s , and elerr.er.ts of the methocoloF'Y knovm ns cla(U~ti c or ptyletic analysis . Intrccuctory sections outline methodoloGY , evidence for viperid mor.opr.yly , currer.t cor.cepts of relationships among viperid snakes , and eccreor,r::lrr.ical features of viperinee . All but two of the approximately 4.$ pecies of tJiperinae have been e:(.1lrJned. · .1.enever feasible bct\ .. een t",o and 15 specimens of e.'lcr.. ~recie::: h.:we l.ef'n examinerl. Features of cranial osteolofY ar.d myolory , vifccr.:1l anato~ , hemipenial morpholof.,y , and "'calation (inclurlinc J~rc~s arr.'ll"r,emcr.t of ~cnlcf and <'"cale t'urfnce microornn. mcnt) , have provided 55 ctnracters of potential cladistic sirnificance . Certain characters appear to be of significance thrm .. 1"001.;+ +1 € f:rcq:- , .... r.ereas otr.ere nre of les!'"e'r importance and arply cl.ly within lineaees estD.bl::i rl ed or. other evidence . t:uTeroue other features have proved impo~sible to interpret in a cladistic context . 1,0 evidence hDs emereed tha t Cal,sue: is closely related to other viperines , but the derived course of the facial carotid artery in the latter dirti n(".ulsh them as a monophyletic group (Viperinae sensu ~. tri.cto) . A.zemi OpS ':'lay be the sLter i'roup of ot.her vipers , ... :::i thin the 1£1 t.ter CaUSllS May be the siE:ter [rot::p of Crotalinae and Vi perinae . Four mjor mcnorhyletic linc3.ces can e proposed among Viperinae s.s. (1) The r;,ur.:lf:ian group (ViPera , fSE'udocerastes . ..... risticophis). (2) Lchjs - Ccrc:.rtes . (3) Pitis . 4) The Atheris £roup (arboreal Attcr'~ , the terre~trial forrr~ 'Atheris' h~ndii ar.d ' Atheri~' S\:";:oerc n j aris , .. ocncrhinos) . It has proved inpos~i le to arrive at a ~ingle hypothesis of the cladidic interrel.:ltions of these four l.'reares , but on balance , it appears more lilely that Echis - Cerastes are more closely related to the advanced African f orms Bitis and the Atheris group , in particular the latter, than to the Eurasian group.

The objective of this study was to examine ecological and behavioural aspects of feeding in the European hedgehog (Erinace~~ eus~aeuB L.) and to attempt to relate these to the accumulation and use of energy. The availability of the invertebrate prey of hedgehogs is shown to vary on a seasonal basis, and to depend also on the weather, habitat, and species of prey animal. For some prey, notably the carabid beetles and earthworms, this variability appears to be relatively predictable. Observations of hedgehog behaviour revealed that animals spent about 80% of their active time foraging regardless of sex. Males spent a greater proportion of their foraging time in neighbouring gardens than did females and also tended to move faster while foraging. Both sexes moved faster in the less dense habitats. Foraging behaviour frequently appeared to exhibit a bimodal pattern, decreasing somewhat during the middle hours of the night and picking up again later on. A study of hedgehog diets revealed that although a wide variety of invertebrates were consumed, the bulk of energy was provided by only four prey types (carabid beetles, earthworms, Lepidoptera larvae, and tipulid larvae). Within these four types, hedgehogs showed a clear tendency to concentrate on only one type at a time and to switch from one group to another on a seasonal basis. Preference indices (which relate diet and availability) suggested that these four prey types plus the gastropods and dermapterans were the preferred prey. There was an implication that the proportion of a given prey type in the diet may have been loosely related to the Length of time spent foraging in a particular habitat. A respirometry technique was used to make estimates of hedgehog energetic requirements. Relationships between resting metabolic rate and body weight and ambient temperature agreed welt with figures reported elsewhere but metabolic rates of' active animals conformed Less well to published data. However, a strong predictive relationship was found between estimates of daily metabolic requirement and body weight, ambient temperature, and the length of time that the hedgehog was active (as opposed to resting). This suggested that an average (600 g) hedgehog would require between 90 and 150 Kcal/day. Estimates of metabolic requirements during hibernation, suggest that hedgehogs lose 0.2% of their original body weight for each day that they spend in hibernation [between 0.8 - 2.0 g/day).

No description available.