This thesis deals with behavioural strategies used by caddis larvae in pairwise contests and when selecting microhabitats. Effects of caddis larvae on survival and habitat selection of other insect taxa have also been studied. The behaviours used by Arctopsyche ladogensis larvae fighting for nets, and Agrypnia pagetana larvae fighting for cases, agreed well with predictions from the sequential assessment game, which is an ESS model of animal fighting behaviour. Establishment by net-spinning Hydropsyche siltalai larvae on artificial substrates was highest at intermediate densities of residents. Emigration/mortality was density independent, and it was higher at a poor site (low food availability) than at a rich site. Establishment was unaffected by site quality. Growth was density dependent because larvae in upstream positions reduced both current velocity and concentration of food particles for larvae in downstream positions. A field experiment involved manipulations of the density of H. siltalai larvae and their nets in a lake outlet stream. H. siltalai larvae affected all abundant taxa, but the mechanism involved varied between taxa. Rhyacophila nubila (Trichoptera) and chironomid larvae benefited from the presence of H. siltalai nets. Negative effects on nymphs of the mayfly Ephemerella ignita were due to predation by H. siltalai larvae, while a combination of predation and increased emigration in response to nets depressed densities of Simulium truncatum blackfly larvae. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1992, härtill 5 uppsatser</p> / digitalisering@umu

Changes in the marine ecosystem can affect the distribution, survival, and reproductive success of seabirds. Therefore, a better understanding of factors influencing the marine distribution and abundance of seabirds can provide insight into ecological hypotheses and have important conservation implications. Yet at-sea habitat selection by seabirds has received far less attention than have investigations of their breeding biology. I studied the patterns and processes of marine habitat selection by seabirds in nearshore waters of Pacific Rim National Park Reserve, Vancouver Island, British Columbia. The study focused on comparative analyses among five sympatric species: marbled murrelet (Brachyramphus marmoratus), common murre (Uria aalge), rhinoceros auklet (Cerorhinca monocerata), pigeon guillemot (Cepphus columba) and pelagic cormorant (Phalacrocorax pelagicus). I used a multi-scaled and multi-disciplined approach combining shore-based telescope observations, vessel-based surveys, and developed new techniques for mapping nearshore seabird distributions. Patterns of habitat selection were examined through vessel-based surveys and species-habitat modeling. Vessel-based transects are fundamental to studies of seabird ecology, yet standardized protocols often fail to account for detectability biases. Distance-sampling methods were used to quantify seabird detectability along transects and showed extensive variability (20-80% of birds detected) depending on species, year, and observer. Corrected estimates of bird densities were used in habitat selection modeling, which demonstrated inter-specific and inter-annual differences in species-habitat associations. Most species showed distinct partitioning in habitats, particularly with respect to substrate and along gradients of depth and sea-surface temperature/salinity. Thus, environmental variability is a key factor structuring habitat use and coexistence in this community of piscivorous seabirds. Processes of habitat selection were studied through observations of foraging behaviour, estimates of prey availability, and spatial-statistical analysis of seabird distributions. Marbled murrelets increased foraging effort in years and seasons with scarce prey and poor oceanographic conditions and decreased foraging effort at sites with high prey availability. Despite their flexible activity budgets, increased foraging effort was inadequate to buffer reproductive success in a poor prey year, suggesting that prey availability is a limiting factor in habitat use and population growth for murrelets. Theodolite-based mapping studies examined the fine-scale distribution patterns of murrelets and murres. Nearest neighbour spatial statistics tested for competition over foraging space and showed avoidance of murres by murrelets. The results of these studies have implications for the management and conservation of the imperiled marbled murrelet in British Columbia and elsewhere in their range. I demonstrate a clear link between prey availability and consequences for reproductive success. Habitat selection models provide a step towards identifying critical marine habitats which must be protected under the Species at Risk Act. Murrelets show high forage site fidelity and associations with spatially fixed habitat components (beaches), suggesting that marine protected areas may have an important role to play in the conservation, management and recovery of murrelet populations.

A fundamental problem in ecology is determining what factors affect the distribution of organisms across a landscape. Landscapes are by their nature heterogeneous and different habitat types confer different fitness benefits and costs to organisms that inhabit them. Ecologists are now aware of the importance of examining multiple spatial scales when designing studies quantifying animal resource selection. Scale of analysis has been shown to be important, since ecological pressures relating to the establishment of a home range differ from those relating to the use of resources within the home range. Most studies that examine multiple spatial scales examine the effect of modifying extent. Here, I examine the role of grain, an underappreciated component of scale, on our interpretation of habitat selection patterns and functional response. The goal of this thesis was to examine how grain size affects the interpretation of animal resource selection and functional response across multiple habitats. The perceptual range of an individual is known to change with habitat, therefore I hypothesized that resource selection and functional response would be both grain- and habitat-dependent, and that resource selection functions computed using different grains for different resources would be more predictive than models computed using only a single grain. I used GPS-collared white-tailed deer (Odocoileus virginianus) to quantify resource selection functions at various grains and used generalized linear mixed effects modelling and multi-model inference techniques to examine how resource selection patterns changed with spatial scale across habitat types. I used selection ratios to examine functional response across grains. Model coefficients changed with grain and the strength of selection varied by habitat type. Multi-grain resource selection functions had lower AIC values and better cross-validation scores than single grain models. Functional response varied with scale and habitat type, displaying a unique relationship for each habitat. My results suggest that spatial memory and habitat-dependent perceptual range play an important role in resource selection. I conclude that the examination of multiple grains in the study of animal habitat selection and functional response represents a step forward in our ability to understand what drives the distribution and abundance of organisms.

Darbo metu buvo nustatyti baltojo gandro gausumo ir erdvinio pasiskirstymo bei lizdaviečių pasirinkimo pokyčiai 1994–2010 metais, ištirti perėjimo buveinės pasirinkimo dėsningumai bei perėjimo sėkmingumo priklausomybė nuo kai kurių buveinės charakteristikų. Baltojo gandro perėjimo buveinės pasirinkimo tyrimai atlikti su 8,4 % pasaulinės perinčios baltojo gandro populiacijos, esančios arealo šiaurės vakarų periferijoje, susitelkusios teritorijoje, užimančioje 1,1 % arealo ploto. Buvo nustatyta, kad tyrimų teritorijoje per 1994–2010 metų laikotarpį ženkliai išaugus baltojo gandro gausumui, paukščiai prisitaikė perėti naujo tipo lizdavietėse – ant elektros oro linijų atramų. Šis prisitaikymas reprodukciniu požiūriu buvo iš dalies neadaptyvus dėl patikimai mažesnio perėjimo sėkmingumo lizduose, susuktuose ant eksploatuojamų elektros oro linijų atramų. Remiantis ilgalaikiais baltojo gandro pirmo atskridimo datos duomenimis, rinktais 1961–2000 metais, buvo nustatytas reikšmingas pavasarinio atskridimo datos į perimvietes arealo šiaurės vakarų periferijoje paankstėjimas. Taip pat buvo nustatyti veiksniai, lemiantys pirmo pavasarinio atskridimo į perimvietes datą. Darbe buvo nustatyti pagrindiniai, perinčiam baltajam gandrui grėsmę keliantys veiksniai, įvertintas jų reikšmingumas ir pasiūlytos neigiamo jų poveikio šiai Europos Sąjungoje saugomai rūšiai sumažinimo priemonės. / In this study, changes during the period 1994–2010 in White Stork abundance and spatial distribution, as well as in nest-site selection were determined; regularities in breeding habitat selection and the effect of some habitat characteristics on the breeding success were investigated. The White Stork habitat selection study was carried out in the north-western periphery of the species’ range on a sample, comprising 8.4% of the total breeding population of this species, concentrated in an area covering just 1.1% of its range. It was revealed that a considerable increase in the White Stork abundance in 1994–2010 coincided with the adaptation by birds to breeding at a new nest-site – on poles of overhead electricity lines. However, from the standpoint of reproduction, this change in the White Stork nesting behaviour was partly non-adaptive due to significantly lower breeding success in nests built on poles of operating overhead electricity lines. Data on the White Stork first spring arrival, collected during the period 1961–2000, revealed a significant advancement of spring arrival date to the breeding grounds in the north-western periphery of the range. Factors, affecting the first spring arrival to breeding grounds, were determined. The main threats facing the breeding White Storks were determined, their importance was assessed, and recommendations for the mitigation of these negative impacts were prepared for this species of the EU conservation concern.

In this study, changes during the period 1994–2010 in White Stork abundance and spatial distribution, as well as in nest-site selection were determined; regularities in breeding habitat selection and the effect of some habitat characteristics on the breeding success were investigated. The White Stork habitat selection study was carried out in the north-western periphery of the species’ range on a sample, comprising 8.4% of the total breeding population of this species, concentrated in an area covering just 1.1% of its range. It was revealed that a considerable increase in the White Stork abundance in 1994–2010 coincided with the adaptation by birds to breeding at a new nest-site – on poles of overhead electricity lines. However, from the standpoint of reproduction, this change in the White Stork nesting behaviour was partly non-adaptive due to significantly lower breeding success in nests built on poles of operating overhead electricity lines. Data on the White Stork first spring arrival, collected during the period 1961–2000, revealed a significant advancement of spring arrival date to the breeding grounds in the north-western periphery of the range. Factors, affecting the first spring arrival to breeding grounds, were determined. The main threats facing the breeding White Storks were determined, their importance was assessed, and recommendations for the mitigation of these negative impacts were prepared for this species of the EU conservation concern. / Darbo metu buvo nustatyti baltojo gandro gausumo ir erdvinio pasiskirstymo bei lizdaviečių pasirinkimo pokyčiai 1994–2010 metais, ištirti perėjimo buveinės pasirinkimo dėsningumai bei perėjimo sėkmingumo priklausomybė nuo kai kurių buveinės charakteristikų. Baltojo gandro perėjimo buveinės pasirinkimo tyrimai atlikti su 8,4 % pasaulinės perinčios baltojo gandro populiacijos, esančios arealo šiaurės vakarų periferijoje, susitelkusios teritorijoje, užimančioje 1,1 % arealo ploto. Buvo nustatyta, kad tyrimų teritorijoje per 1994–2010 metų laikotarpį ženkliai išaugus baltojo gandro gausumui, paukščiai prisitaikė perėti naujo tipo lizdavietėse – ant elektros oro linijų atramų. Šis prisitaikymas reprodukciniu požiūriu buvo iš dalies neadaptyvus dėl patikimai mažesnio perėjimo sėkmingumo lizduose, susuktuose ant eksploatuojamų elektros oro linijų atramų. Remiantis ilgalaikiais baltojo gandro pirmo atskridimo datos duomenimis, rinktais 1961–2000 metais, buvo nustatytas reikšmingas pavasarinio atskridimo datos į perimvietes arealo šiaurės vakarų periferijoje paankstėjimas. Taip pat buvo nustatyti veiksniai, lemiantys pirmo pavasarinio atskridimo į perimvietes datą. Darbe buvo nustatyti pagrindiniai, perinčiam baltajam gandrui grėsmę keliantys veiksniai, įvertintas jų reikšmingumas ir pasiūlytos neigiamo jų poveikio šiai Europos Sąjungoje saugomai rūšiai sumažinimo priemonės.

The choice of a place to live and reproduce is crucial for species� survival in providing them with adequate resources and shelter from predators or climatic conditions. Determining habitat suitability in endangered species is important for the success of translocation as a conservation tool. In addition, understanding mechanisms (source/sink system versus ecological traps) that drive habitat selection in translocated animals may be critical to population viability. In New Zealand, where ecosystems are highly vulnerable to extinction, habitat restoration on predator-free off-shore islands is an important recovery tool. Therefore, there is a need to understand the relationship between the establishment of the translocated populations and the characteristics of their new environment. Previous research indicated that re-introduced populations of Stewart Island robin (Petroica australis rakiura - Toutouwai) and South Island saddleback (Philesternus carunculatus carunculatus - Tieke) on Ulva Island (Stewart Island), New Zealand, showed preferences for coastal habitats that were characterized by low-lying dense vegetation and open ground cover. In this study, we further investigated territorial establishment in these two populations since re-introduction and looked at how birds utilised the landscape. I hypothesised that sites colonised soon after re-introduction were of high quality and later on, birds moved into unsuitable habitats. I defined habitat quality at a micro-scale in terms of vegetation structure, nest characteristics and food availability. I modeled bird presence and nesting success in relation to habitat components to determine factors in the environment that influenced breeding site selection and contributed to successful nesting in these two species. I discussed results in comparison to similar bird-habitat models developed for the South Island saddleback population on Motuara Island (Marlborough Sounds) and examined explanatory variables in each model. Translocated birds in the three studied populations first established territories in coastal scrub, and in the following years moved into larger coastal forest stands. Although vegetation structure was the primary variable explaining site selection in these populations, vegetation composition should still be considered important as it dictated the suitability of nesting substrate and the availability of food items. There was no evidence that first-colonised areas were more suitable habitats, and I concluded that these cases could not be used as examples of ecological traps. Instead, results suggested that with increased density robins and saddlebacks on Ulva have more recently settled in sites less suitable to nesting and foraging, thus underlying a source/sink structure. However, the sparse distribution of food items on Motuara contributed to a lack of territorial behavior and environmental effect on breeding success; therefore a source/sink system could not be confirmed in this population. I recommended that future translocation sites give preference to mixed-size stands with broadleaved species that are characterised by dense canopy below 4 m height and with suitable cavities in live trees. Lastly, due to robins� and saddlebacks� attraction to conspecifics and their territorial behavior, resources evenly distributed across the landscape could also increase their survival and reproductive success.

Thesis (Ph.D.)--Mississippi State University. Department of Biological Sciences. / Title from title screen. Includes bibliographical references.

Tout au long de leur vie, les individus sont confrontés à deux décisions qui ont des conséquences majeures sur leur succès reproducteur : où et quand se reproduire. Cette thèse étudie les mécanismes sous-jacents à ces décisions, à travers trois études basées sur des données de suivis individuels chez la mouette tridactyle (Rissa tridactyla) et le goéland railleur (Chroicocephalus genei). La première étude porte sur la dispersion chez la mouette tridactyle. La probabilité de quitter le site de reproduction est décomposée selon une structure hiérarchique des patchs d'habitat. Une hypothèse synthétique est exposée pour expliquer la stratégie de sélection de l'habitat en intégrant les coûts de la dispersion et l'utilisation de l'information sur la qualité de l'habitat. La seconde étude s'appuie sur un modèle de population intégré chez la mouette tridactyle pour estimer l'immigration, le recrutement, et la reproduction intermittente. Cette étude interroge la relation entre information sociale sur l'habitat et décision de se reproduire dans une population qui est située en bordure d'aire de répartition. La troisième étude porte sur le recrutement et la dispersion chez le goéland railleur, caractérisé par un fort nomadisme de reproduction. Des modèles de capture-recapture multi-évènements sont employés pour quantifier les variations liées à l'âge et au sexe. Ces exemples permettent d'aborder l'importance des contraintes imposées par la variabilité de l'habitat et la compétition intraspécifique dans le processus d'accès à la reproduction. / Throughout their lifetime, individuals face two decisions which have major consequences on the reproductive success: where and when to breed. This thesis explores the mechanisms underlying these decisions through three studies based on individual monitoring data in the black-legged kittiwake (Rissa tridactyla) and the slender-billed gull (Chroicocephalus genei). The first study addresses hypotheses on dispersal in the kittiwake. The probability of leaving the nest site is sequenced according to the hierarchical structure of habitat patches. A synthetic hypothesis that integrates the costs of dispersal and the use of information on habitat quality is suggested to explain the strategy of habitat selection. The second study uses a population integrated model in the kittiwake to estimate immigration, recruitment, and intermittent reproduction. This study investigates the relationships between social information on the habitat and the decision to breed in a population which is located at the edge of the species range. The third study focuses on recruitment and dispersal in the slender-billed gull which is characterized by a high degree of nomadic breeding. Multievent capture-recapture models are used to quantify sex- and age-dependent variations. These examples enable to address how important the constraints of habitat variability and intraspecific competition are in the process of obtaining a breeding position.

La chasse – comme la prédation naturelle - induit des réponses comportementales par les individus chassés qui cherchent ainsi à éviter ou à reduire le risque. Il est en particulier fréquent d'observer un changement dans leur utilisation de l'espace, mais l'articulation et les déterminants des réponses aux différentes échelles spatiales restent mal compris. De même, s'il a été suggéré que ces modifications comportementales pouvaient affecter en cascade la végétation, cela reste à tester. Pour combler ces lacunes, j'ai, (1) étudié, dans un paysage agricole du sud de la France, une population chassée de chevreuils et leur utilisation des milieux ouverts risqués et des couverts boisés, au cours de périodes de risque contrasté ; (2) testé, sur une population canadienne de cerfs à queue noire dépourvue de prédateurs et exempte de chasse, l'influence d'une chasse expérimentale sur le comportement des animaux et sur la végétation. J'ai montré que les chevreuils répondaient à une augmentation du risque à plusieurs échelles spatiales. Ils réduisaient leur utilisation des habitats risqués, et dans certains cas se rapprochaient des couverts, de jour ces deux réponses étant couplées au niveau individuel. Le gradient paysager d'ouverture du milieu contraignait cependant les niveaux de réponses observées et les stratégies individuelles. Au Canada, j'ai observé un évitement de la zone chassée par les cerfs les plus sensibles à la présence humaine, corrélé à une diminution de l'abroutissement pour deux des quatre espèces de plantes étudiées. J'ai intégré ces résultats dans une discussion sur l'utilisation de la chasse pour gérer les populations d'herbivores et leurs impacts sur la végétation. / Hunting – similarly to natural predation – induces behavioural responses of hunted individuals which aims at avoiding or reducing risk. Particularly, changes in space use are frequently observed, but the articulation and determinants of these changes at multiple spatial scales are still poorly understood. Also, although it has been suggested that these changes might cascade on the vegetation, this remains to be tested. To fill these gaps, I (1) studied a hunted roe deer population living in an agricultural landscape in southern France where roe deer can find open risky habitats and woody covers; and (2) tested black-tailed deer behavioural response to an experimental hunt in a predator- and hunting-free population in the Haïda-Gwaii archipelago (BC, Canada). I also investigated the possible cascading effects on the vegetation. I showed that roe deer responded to increased hunting pressure at multiple scales, reducing their use of the risky habitats and, in specific situations, their distance to the nearest cover. At day-time those two responses were coupled at the individual level. Generally, landscape openness constrained individual responses and strategies. In the hunting-for-fear experiment conducted on Haida Gwaii, I found that only the deer less-tolerant to human disturbance avoided the hunting area. A simultaneous reduction in browsing pressure on two out of the four plant species monitored was found however. I integrated these results in a general discussion on the possible role of hunting as a tool to manage abundant deer populations and their impacts on the vegetation.

abstract: Species conservation requires an understanding of the habitats on which that species depends as well as how it moves within and among those habitats. Knowledge of these spatial and temporal patterns is vital for effective management and research study design. Bubbling Ponds Hatchery in Cornville, Arizona, supports a robust population of the northern Mexican gartersnake (Thamnophis eques megalops), which was listed as threatened under the Endangered Species Act in 2014. Natural resource managers are interested in understanding the ecology of gartersnakes at this site to guide hatchery operations and to serve as a model for habitat creation and restoration. My objectives were to identify habitat selection and activity patterns of northern Mexican gartersnakes at the hatchery and how frequency of monitoring affects study results. I deployed transmitters on 42 individual gartersnakes and documented macro- and microhabitat selection, daily and seasonal activity patterns, and movement distances. Habitat selection and movements were similar between males and females and varied seasonally. During the active season (March–October), snakes primarily selected wetland edge habitat with abundant cover and were more active and moved longer distances than during other parts of the year. Gestating females selected similar locations but with less dense cover. During the inactive season (November–February), snakes were less mobile and selected upland habitats, including rocky slopes with abundant vegetation. Snakes displayed diurnal patterns of activity. Estimates of daily distance traveled decreased with less-frequent monitoring; a sampling interval of once every 24 hours yielded only 53–62% of known daily distances moved during the active season. These results can help inform management activities and research design. Conservation of this species should incorporate a landscape-level approach that includes abundant wetland edge habitat with connected upland areas. Resource managers and researchers should carefully assess timing and frequency of activities in order to meet project objectives. / Dissertation/Thesis / Masters Thesis Applied Biological Sciences 2017