Rotas por veículos foram realizadas para que a riqueza, a abundância e o uso do habitat por rapinantes diurnos no Parque Estadual Veredas do Peruaçu (30.702 ha), Minas Gerais, fosse estudada. Onze rotas foram selecionadas e distribuídas em dois habitats: cerrado (n=6) e uma associação entre vereda e cerrado (n=5). O estudo foi realizado entre setembro de 2010 e julho de 2011 por três observadores na carroceria de um veículo 4x4 dirigido a uma velocidade média de 20km/h, totalizando 2772 km percorridos. Ao longo das transecções foram obtidos 681 registros (0,24 rapinantes/km), referentes à 20 espécies, contudo, Falco peregrinus foi registrado ao longo das amostragens ad libitum e elevou a riqueza. As cinco espécies mais comuns foram Heterospizias meridionalis, Caracara plancus, Milvago chimachima, Rupornis magnirostris e Falco femoralis, as quais totalizaram aproximadamente 20% da riqueza local e 80% de todos os registros. As cinco espécies mais raras (Leptodon cayanensis, Elanus leucurus, Accipiter bicolor, Micrastur semitorquatus e Falco sparverius), juntas, representaram menos de 1% das detecções. As aves de rapina foram mais abundantes ao longo da estação chuvosa (n=438), se comparada à seca (n=243). As veredas apresentaram maior riqueza (19 contra 10 taxa) e quase três vezes mais registros (n=466; 0,36 rapinantes/km) que o cerrado (n=215; 0,14 rapinantes/km). O número de detecções computadas para as manhãs foi maior do que as anotadas para as tardes. Baseado no ΔAICc, os modelos que melhor explicaram a riqueza e abundância dos rapinantes continham todas as três variáveis independentes (habitat, estação e período do dia). Rotas por veículos aparentaram ser indicadas para estudos com rapinantes em habitats similares a savanas. O cerrado local apresentou menor riqueza e abundância se comparado às veredas, entretanto, o habitat ocupa grandes proporções e deve possuir importante papel na conservação dos rapinantes. A vereda delimita o parque ao norte e nela foram registradas espécies restritas ao ambiente, como a águia-cinzenta (Urubitinga coronata), taxon mundialmente ameaçado de extinção. Tal fato eleva a importância do habitat para o grupo e, consequentemente, para toda a comunidade. Sugere-se que o parque tenha sua área aumentada em sua porção norte, considerando que, adicionalmente, grande parte da água corrente provém desta porção. / Raptors were surveyed by road transects in order to assess local species richness, abundance and habitat use in Parque Estadual Veredas do Peruaçu (30,702 ha), a reserve that lies in the Cerrado Region of southeastern Brazil. Eleven road transects of 7km each were delimited in two different habitats: cerrado (n=6) and an associated vereda-cerrado (n=5). Transects were sampled between September 2010 and July 2011 by three observers on the back of a 4WD pickup truck, driven at an average speed of 20km/h - total of 2772 km. There were computed 681 records along road transects (0.24 raptors/km), belonging to 20 species. One other species (Falco peregrinus) was recorded exclusively along ad libitum sampling. The five most common raptors were Heterospizias meridionalis, Caracara plancus, Milvago chimachima, Rupornis magnirostris and Falco femoralis, which totalized approximately 20% of local richness and 80% of all records. The five rarest raptors in the study area (Leptodon cayanensis, Elanus leucurus, Accipiter bicolor, Micrastur semitorquatus and Falco sparverius), together, represented less than 1% of all records. Raptors were more abundant during rainy season (n=438) than during dry season (n=243). The veredas presented higher species richness (19 against 10 taxa) and almost three times more records (n=466; 0.36 raptors/km) than the cerrado (n=215; 0.14 raptors/km). Mornings held higher number of records when compared to afternoons. Based on ΔAICc the models that better explained species richness and raptors\' abundance had all three explanatory variables (habitat, season and day period) considered. Road transects seemed to be recommended for surveys in savannah like habitats. The local cerrado presented lower raptor richness and abundance when compared to the vereda, however it occupies most of the region and it should have an important role on raptors\' conservation. The vereda delimit the reserve northern boundaries and it holds some locally restricted taxa, like the Crowned Eagle (Urubitinga coronata) a species globally threatened of extinction. This makes the habitat even more important for these species and, consequently, to local ecological community. The fact that the vereda is protected only by one margin is a worrying issue and it is suggested that the reserve boundaries augment northwards, once important water supply also comes from there.

Lateral habitats provide a multitude of benefits to riverine fishes, including invasive Silver Carp (Hypophthalmicthys molitrix) and Bighead Carp (H. nobilis), hereafter bigheaded carp. Harvesters have focused removal efforts in lateral habitats (e.g., backwaters and side channels); however, little research has examined the lateral habitat use of bighead carps. The Starved Rock Pool (SRP) is the downstream most pool in the upper Illinois River where contracted commercial fishermen target bigheaded carp to reduce dispersal pressure towards the Laurentian Great Lakes. To examine bigheaded carps’ movement between the main channel and lateral habitats in SRP, fish were implanted with transmitters and tracked using acoustic telemetry. The ranges and detection probabilities of acoustic telemetry receivers have typically been modelled and examined in with linear distance tools. To derive more realistic receiver ranges and detection probabilities, this study used minimum bounding geometry on detected transmissions obtained from boat-mounted transmitters. Receiver detection ranges estimated using minimum bounding geometry were smaller than those estimated using the linear distance method, but estimated detection probabilities within receiver ranges were higher using the minimum bounding method compared to the linear distance method. Detection histories of bigheaded carp implanted with transmitters were examined to assess fish habitat use from June 2016 to April 2018. During 2017, multiple environmental variables (temperature, river discharge, chlorophyll a, dissolved oxygen, total dissolved solids, and turbidity) were measured weekly and zooplankton samples were collected during June and August to assess potential associations between environmental variables and bigheaded carp habitat use that might be useful for informing locations and times for focusing contracted harvest of bigheaded carps. Habitat selection was also examined using a resource selection index (W) and a mark-recapture multistate model in program MARK. Across all seasons, bigheaded carp used lateral habitats more frequently than main channel habitats. Habitat use was strongly influenced by temperature and marginally by main channel discharge. No strong associations between zooplankton and bigheaded carp habitat use were observed during this study; however, there were some differences in zooplankton community structure and abundance among lateral habitats related to rotifers that may have potentially been related to use of specific lateral habitats by bigheaded carp. While having high return percentages to all lateral habitats, bigheaded carp disproportionately selected for a few individual habitats, possibly due to those habitats being locations where tagging was conducted. Harvest efforts in lateral habitats, especially prior to spawning (spring staging), during lower temperature periods (overwintering), and during higher discharges should be most effective because of bigheaded carps’ particularly high use of lateral habitats during these times. Recurring removal efforts in lateral habitats within SRP may facilitate targeting of individuals that frequently return to these lateral habitats and may also reduce bigheaded carp abundance in nearby locations.

Master of Science / Department of Horticulture and Natural Resources / Adam A. Ahlers / The muskrat (Ondatra zibethicus) is an economically and ecologically important furbearer species that occupy wetlands throughout North America. However, populations across the United States (US) are declining and there is little evidence as to the cause of this decline. Wetlands in the upper Midwest, US, are shifting into more homogeneous vegetation states due to an invasive hybrid cattail species, Typha x glauca (hereafter ‘T. x glauca’), outcompeting native vegetation. This hybrid cattail species is now an abundant potential resource for muskrats and has outcompeted native wetland vegetation. I investigated how landscape composition and configuration affected multiscale habitat use by muskrats during the summers of 2016 – 2017. Additionally, I assessed how fetch (impact of wind and wave action), a process dictated by large-scale landscape configuration, influenced muskrat habitat use at a local-scale representing a resource patch. I randomly selected 71 wetland sites within Voyageurs National Park, Minnesota, and used presence/absence surveys to assess site occupancy by muskrats. Each year, multiple surveys were conducted at each site and I used multiseason occupancy modeling to investigate how both local and landscape factors affect site occupancy and turnover. I predicted a positive relationship between local-scale (2 ha) sites, characterized by shallower and less open water, and muskrat occupancy and colonization rates. I also predicted increased occupancy probabilities and colonization rates in wetlands that contain higher amounts of T. x glauca. However, I expected the amount of fetch at each site to negatively influence site occupancy probabilities and colonization rates. At the landscape-scale (2 km), I expected habitat use by muskrats to be positively related to the percentage of T. x glauca and area of wetlands surrounding sites. At the local-scale, muskrats occupied wetlands that contained shallower water depths and less open water. As predicted, site occupancy probabilities were greater in areas with greater amounts of T. x glauca coverage. My results revealed a cross-scale interaction between the severity of fetch impacts and percent of T. x glauca coverage at sites. Muskrats were more likely to colonize areas with greater fetch impacts if there was also greater coverage of T. x glauca at these sites. At the landscape-scale, site-occupancy probabilities were positively influenced by the percent of open water and landscape heterogeneity surrounding each site. My study was the first to document how invasive T. x glauca populations can mitigate negative effects that high wave intensity may have on muskrat spatial distributions. I was also the first to identify multiscale factors affecting the spatial distribution of muskrats in lacustrine ecosystems.

Le sujet de thèse porte sur l'étude des baleines à bosse, espèce migratrice. L'objectif est, à partir del'étude de leurs déplacements, de mieux comprendre leur distribution, leurs comportements, leurstratégie d'alimentation et de reproduction. Ce travail s'appuie sur plusieurs missions dédiées à lapose de balises satellitaires sur des individus évoluant dans les zones d'alimentation (Arctique) et leszones de reproduction (Caraïbes).La thèse est articulée autour de 4 articles. Le 1er intitulé "From whaling to tagging: the evolution ofknowledge regarding humpback whales in their North Atlantic breeding grounds" décrit l'historiquedes connaissances actuelles sur la population de baleine à bosse de l'Atlantique Nord, à partir desinformations consignées lors de la chasse industrielle à la baleine jusqu'aux observations les plusrécentes.Le 2e chapitre, intitulé "Local and migratory movements of humpback whales satellite tracked in theNorth Atlantic Ocean", détaille les routes migratoires sud-nord d'individus de RépubliqueDominicaine (Silver Bank) et de Guadeloupe (Antilles françaises). Dans un 1er temps, nous noussommes focalisées sur les déplacements dans la zone de reproduction. Les résultats ont montré unetrès grande mobilité, remettant en cause les hypothèses établies visant à décrire des individusrestant sur une zone donnée (pour les groupes actifs et/ou les chanteurs par exemple). Nous avonségalement montré des mouvements erratiques, sans pouvoir définir un modèle de prédiction detrajectoires à moyen terme (c'est-à-dire sur plusieurs jours). Dans un 2e temps, nous avons travaillésur les routes migratoires, qui restent encore actuellement un sujet de recherche majeur pour cetteespèce de mammifères qui détient le record avec plus de 6000km par trajet entre ses airesd'alimentation et de reproduction, avec 2 objectifs en particulier : d'une part, mieux appréhender lesmotivations des individus pour privilégier telle ou telle route migratoire, et d'autre part, savoir si lesroutes migratoires contribuent au mixage des différents stocks des baleines à bosse. Nos résultatsont montré clairement 2 routes privilégiées par les baleines à bosse de la Caraïbe : les individusprésents en République Dominicaine remontaient le continent américain, alors que ceux deGuadeloupe choisissaient une voie transatlantique, vers l'Islande et potentiellement la Norvège.Le 3e chapitre, basé sur l'article : "Individual variation in movements of humpback whales satellitetracked in the eastern Aleutian Island and Bering Sea", est dédié à l'étude des déplacements desbaleines à bosse pendant leur période d'alimentation près du Dutch Harbor en Alaska, de 2007 à2011. Nous avons montré les habitats des baleines à bosse dans cette région. Nous avons égalementprécisé les stratégies individualistes pour s'alimenter.Le dernier chapitre, basé sur le chapitre "Assessing implantable satellite tag extrusion using lightsensors", présente les difficultés actuelles de l'utilisation des balises Argos, pour l'étude des baleinesà bosse. Cela concerne principalement le système d'attache. L'objectif est d'avoir une idée sur lavitesse d'éjection et de voir s'il y a une corrélation entre la façon de poser la balise, son endroit sur labaleine et la durée totale de maintien sur l'individu.Pour conclure, ce travail a mis en évidence de nouvelles connaissances sur les stratégies individuellesdes baleines à bosse dans leurs aires d'alimentation, de reproduction mais aussi au cours des routesmigratoires. L'utilisation des balises satellitaires est une nouvelle alternative attractive pour l'étudede cette espèce hautement mobile. / This dissertation has been prepared in manuscript format and contains four individual papers. Each paper/chapter is formatted for the journal to which it has been, or will be, submitted. In the first manuscript, “From Whaling to Tagging: The evolution of knowledge regarding humpback whales in their North Atlantic breeding grounds”, I describe the evolution of humpback whale research from the days of Yankee whaling to the most recent satellite telemetry project in the West Indies breeding grounds. The humpback whales that over-winter in the West Indies are part of one of the most heavily studied whale populations in the world; projects conducted in this area have served as models for humpback whale research world-wide. This manuscript will be submitted for publication in Mammal Review in 2014. In my second manuscript, “Local and migratory movements of humpback whales satellite tracked in the North Atlantic Ocean”, I report the results of a satellite telemetry project that was conducted in the winters of 2008 through 2012 in the breeding areas of Silver Bank (Dominican Republic) and Guadeloupe (French West Indies). The results from this project add a level of detail to the current knowledge about North Atlantic humpback whale habitat use, migration, and population structure that could not be obtained without current satellite tagging technology. This paper has been reviewed and accepted for publication by the Canadian Journal of Zoology and will be published by November, 2013 ii In my third manuscript, “Individual variation in movements of humpback whales satellite tracked in the eastern Aleutian Islands and Bering Sea”, I report the results from a satellite telemetry project conducted off Dutch Harbor, (Alaska, USA) in the summers of 2007 through 2011. Satellite telemetry from this project showed the fine-scale use of foraging habitat in a North Pacific feeding ground. Additionally, a long-distance, within-season travel event was recorded in 2010, prompting speculation about the humpback population structure throughout the Bering Sea. This manuscript has been reviewed and accepted for publication by Endangered Species Research and will be published by November, 2013. In the fourth manuscript, “Assessing implantable satellite tag extrusion using light sensors”, I report the results of a novel approach for remotely quantifying tag rejection; the use of tag-mounted light sensors to indicate extrusion rate. The data for this paper were collected during a 2011 follow-up study aimed at assessing the behavioral and physiological responses of Gulf of Maine humpback whales to current tagging methods. Tag diagnostic technology like this, while still being developed, could significantly improve future telemetry work by updating tag design and placement methods to increase overall project efficiency. This paper has been accepted as a poster presentation at the 20th Biennial Conference on the Biology of Marine Mammals (December 2013, Dunedin New Zealand). It will be updated with the results from the 2013 Gulf of Maine tagging field season and submitted to a peer reviewed journal in 2014.

The central objective of this thesis is to better understand early life history dynamics of salmonids in large regulated rivers. I studied spawning, incubating, and age-0 life stages of rainbow trout in the Lee’s Ferry reach of the Colorado River below Glen Canyon Dam, AZ. My first objective was to evaluate the effects of hourly fluctuations in flow on nearshore habitat use and growth of age-0 trout. Catch rates in nearshore areas were at least 2- to 4-fold higher at the daily minimum flow compared to the daily maximum and indicated that most age-0 trout do not maintain their position within immediate shoreline areas during the day when flows are high. Otolith growth increased by 25% on Sundays in one year of study, because it was the only day of the week when flows did not fluctuate. My second objective was to evaluate the effects of flow fluctuations on survival from fertilization to a few months from emergence (early survival). Fluctuations were predicted to result in incubation mortality rates of 24% in 2003 and 50% in 2004, when flow was experimentally manipulated to reduce trout abundance, compared to 5% in 2006 and 11% in 2007 under normal operations. Early survival increased by over 6-fold in 2006 when egg deposition decreased by at least 10-fold. Because of this strong compensatory dynamic, flow-dependent incubation mortality in experimental years was likely not large enough to reduce the abundance of age-0 trout. My final objective was to determine how flow, fish size and density effects habitat use, growth, and survival of age-0 trout. Apparent survival rates from July to November were 0.18 (2004), 0.19 (2006), and 0.32 (2007). A stock synthesis model was developed to jointly estimate parameters describing early life history dynamics, and indicated that early survival was lower for cohorts fertilized during the first half of the spawning period and was negatively correlated with egg deposition, that movement of age-0 trout from low- to high-angle shorelines increased with fish size, and that survival varied by habitat type and over time in response to flow changes from Glen Canyon Dam.

The central objective of this thesis is to better understand early life history dynamics of salmonids in large regulated rivers. I studied spawning, incubating, and age-0 life stages of rainbow trout in the Lee’s Ferry reach of the Colorado River below Glen Canyon Dam, AZ. My first objective was to evaluate the effects of hourly fluctuations in flow on nearshore habitat use and growth of age-0 trout. Catch rates in nearshore areas were at least 2- to 4-fold higher at the daily minimum flow compared to the daily maximum and indicated that most age-0 trout do not maintain their position within immediate shoreline areas during the day when flows are high. Otolith growth increased by 25% on Sundays in one year of study, because it was the only day of the week when flows did not fluctuate. My second objective was to evaluate the effects of flow fluctuations on survival from fertilization to a few months from emergence (early survival). Fluctuations were predicted to result in incubation mortality rates of 24% in 2003 and 50% in 2004, when flow was experimentally manipulated to reduce trout abundance, compared to 5% in 2006 and 11% in 2007 under normal operations. Early survival increased by over 6-fold in 2006 when egg deposition decreased by at least 10-fold. Because of this strong compensatory dynamic, flow-dependent incubation mortality in experimental years was likely not large enough to reduce the abundance of age-0 trout. My final objective was to determine how flow, fish size and density effects habitat use, growth, and survival of age-0 trout. Apparent survival rates from July to November were 0.18 (2004), 0.19 (2006), and 0.32 (2007). A stock synthesis model was developed to jointly estimate parameters describing early life history dynamics, and indicated that early survival was lower for cohorts fertilized during the first half of the spawning period and was negatively correlated with egg deposition, that movement of age-0 trout from low- to high-angle shorelines increased with fish size, and that survival varied by habitat type and over time in response to flow changes from Glen Canyon Dam.

Sperm whales (Physeter macrocephalus) are widely distributed in all oceans, but principally found in areas of high primary productivity. Historically, they were whaled extensively in the Sargasso Sea and recent surveys have also found large numbers there. However, the Sargasso Sea is an oceanic gyre considered to be low in productivity. This dissertation explores the paradox of a high abundance of large top predators in a body of water once described as an “oceanic desert”. First, I compared the diet of sperm whales in the Sargasso Sea to those off Dominica, in the eastern Caribbean. Results suggested differences in trophic ecology between these two areas, with sperm whales in the Sargasso Sea feeding at a higher trophic level. Second, I examined the spatial and temporal distribution of sperm whales in the Sargasso Sea in relation to environmental variables using acoustic surveys and autonomous recording devices. Sperm whale prevalence around Kelvin seamount, part of the New England Seamount Chain, was higher in the spring compared to the winter. Habitat modeling results suggest that the mesoscale activity associated with the Gulf Stream plays an important role in sperm whale occurrence in this area, likely due to the enhancement of primary productivity in this region. Finally, I estimated the current density of sperm whales in the northwestern Sargasso Sea and compared their present distribution to their distribution during the open-boat whaling era (1775-1921). Sperm whale density in the northern Sargasso Sea is one of the highest found globally, showing that this region remains a hotspot for sperm whales. The area where sperm whale detections per unit effort is presently the highest showed little overlap with areas where whales were hunted historically. Whalers all but ignored this region except when transiting to other whaling grounds, perhaps a result of fixed whaling patterns due to the conservative use of knowledge at that time. My dissertation highlights patterns and processes that help to explain the presence and abundance of sperm whales in the Sargasso Sea and demonstrates the importance of western boundary currents, such as the Gulf Stream, to the distribution of marine top predators.

This study provides a biological perspective on the potential of using year-round sanctuaries to protect largemouth bass (Micropterus salmoides). Although the Rideau Lakes bass sanctuaries have been present for more than 70 years, a lack of empirical rationale has resulted in a considerable debate regarding their usefulness. Using radio telemetry in Lake Opinicon, Ontario, the current study indicates that largemouth bass behaviour is influenced by the structural complexity of the habitats they occupy. In high-structure habitats, bass tend to have smaller utilization areas, displacement rates and radial displacements relative to those occupying low-structure habitats. All largemouth bass were captured and released (after transmitter implantation) in high-structure areas; however, more than half (12 of 23) of these individuals made spring (closed fishing season) relocations to low-structure areas where most (11 of 12) remained for the duration of the study. Behaviour is important to consider because of the influence it has on the level of sanctuary protection received by a largemouth bass. Twelve individuals began the study in the high-structure habitats of Lake Opinicon’s Murphy Bay fish sanctuary; however, only five remained in high-structure habitats throughout the study to receive full open season protection, two others received partial protection and four largemouth bass received no open season sanctuary protection because they made spring relocations to low-structure areas outside of the sanctuary. The results of this study provide an important biological perspective for the evaluation of year-round bass sanctuaries. Further research is needed to understand the specific causes of observed behaviours and to investigate how open and closed season protection of a year-round sanctuary translates into overall bass fishery benefits. Therefore, we recommend the maintenance of the Rideau Lakes bass sanctuaries as year-round regulations until there is sufficient empirical evidence to support their re-designation or removal. / Thesis (Master, Biology) -- Queen's University, 2010-04-01 01:39:20.969

Albatross populations are currently in decline around the world. Survival and reproduction of these large pelagic birds depends mostly on the conditions they encounter in their marine environment. Their ability to range far across ocean basins exposes them to a variety of anthropogenic threats. It is thus crucial to understand spatial and temporal patterns in the distribution and habitat use of each albatross species during different stages of their annual cycle in the context of seasonally changing demands as well as environmental constraints, in order to develop effective conservation measures. Using Global Location Sensing (GLS) loggers I investigated the non-breeding movements and habitat associations of three threatened or near-threatened albatross species breeding in New Zealand’s Chatham Islands, the Chatham Albatross (Thalassarche eremita), Northern Buller’s Albatross (T. bulleri platei) and Northern Royal Albatross (Diomedea epomophora sanfordi), within South American waters. Chatham and Northern Buller’s Albatrosses mainly occupied waters with mean sea surface temperatures (SST) of 17-18ºC along the coasts of Chile and Peru, while Northern Royal Albatrosses were mostly found in 10-12ºC waters off southern Chile and Argentina. Monthly movement patterns were linked to seasonal shifts in temperature range, suggesting SST was an important environmental factor in explaining the observed spatial and temporal patterns. GLS loggers were also applied to study the patterns of movement and habitat use of Chatham Albatrosses when migrating across the South Pacific between breeding and non-breeding grounds. The route and timing of migration were consistent over the three year period of the study, although subject to individual variation. Stopovers on migration were found to be common, lasting between 3 and 26 days. Activity patterns suggested that birds stopped in order to forage en route. Lastly, I used high resolution Global Positioning Sensing (GPS) loggers to address the fine-scale movements and habitat selection of foraging Chatham Albatrosses over three years during early chick rearing. This is a time when their behaviour is expected to respond to increased energetic demands as they are feeding young chicks. Foraging trips lasted between 1 and 6 days and the foraging range rarely exceeded 400 km. The location of potential foraging spots varied between years, but followed non-random patterns in bathymetry, slope, SST and Chlorophyll a. The results presented here suggest that albatrosses rely on predictable habitat features but are flexible to respond to fine scale changes within their marine environment. The dynamic nature of both birds and environment may prove challenging but has to be taken into account in conservation planning.

Declines and extinctions of amphibian populations are a global dilemma with complex local causes, which should be viewed in the context of a much larger biodiversity crisis. As other animal groups, amphibians with restricted distributions, such as island endemics, are thought to be more vulnerable to environmental change and susceptible to population declines. In the New Zealand archipelago, the only four native species of frogs (Leiopelma hochstetteri, L. archeyi, L. hamiltoni and L. pakeka) are classified as threatened. In particular Leiopelma hochstetteri, the most widespread and abundant endemic frog species in New Zealand, now survives only in spatially fragmented populations as a result of direct or indirect human activity. Hence, it is recognised as threatened and fully protected by legislation. In the last fifty years, some L. hochstetteri populations have been studied, providing descriptive information, which may be used to assess the current status (increasing, stable or declining) of previously or never monitored populations. This thesis examines the diet and trophic level, the effects ship rats (Rattus rattus) as well as the distribution and abundance of L. hochstetteri on a habitat-use context, to provide a basis for evaluating conceivable decline-agents, and to establish a platform to design directed conservation strategies. The Waitakere Ranges are considered a Leiopelma hochstetteri conservation management unit, on which L. hochstetteri has been previously studied. This area consists of a series of hills that run roughly north–south, which are mostly covered in regenerating indigenous vegetation. Today, 60% of the Waitakere Ranges fall within a Regional Park, which together with its surrounding residential areas is afforded protection to minimise the effects of development on the region. The accessibility and conservation character of this area makes it an ideal area for the study of L. hochstetteri populations. As a first step to characterise the diet and trophic level of L. hochstetteri within streams in the Waitakere Ranges, Auckland, stable carbon and nitrogen isotope analyses were undertaken on a variety of sympatric terrestrial and aquatic plant and animal species, including adult frogs. These results showed that: 1) aquatic and terrestrial food webs were linked by terrestrial inputs into the stream; 2) invertebrate and vertebrate predators separated well into distinct trophic groups; and 3) L. hochstetteri occupied an intermediate trophic position among predators, with a diet, at least as an adult, comprising terrestrial invertebrates. Shortfin eels and banded kokopu were identified as potential predators of L. hochstetteri, but data for rats were inconclusive. The inconclusiveness of these trophic studies, with regard to the effects of ship rats on L. hochstetteri populations, lead me to evaluate the influence of a seven-year ship rat management operation on frog abundance. To achieve a reliable evaluation, the habitat characteristics that had significant influence on frog abundance were identified. Then, it was confirmed that the study areas represented similar habitats in terms of those variables, and finally the effect of the pest-management activities was evaluated. Presence/absence of pest-management operations did not have a significant effect on frog abundance. These results, together with the results of the diet and trophic level analyses, suggested that ship rats do not represent a significant threat for this frog species, at least in the Waitakere Ranges. The results of distribution and abundance investigations indicated that in the Waitakere Ranges frogs are currently widely distributed, relatively abundant and that recruitment has occurred at least in the last ten years. Additionally, in order to identify associations between habitat characteristics and frog distribution and abundance, reliable and specifically designed monitoring methodologies were developed. Although this frog is known to occur in wet areas adjacent to shaded streams in forested catchments, quantitative ecological data previously did not exist to enable characterisation of its habitat. Here, novel data were reported on the current distribution and habitat requirements of this species in the Waitakere Ranges. Statistical modelling demonstrates frogs most likely occur in small, erosive streams with coarse substrates and cold waters, surrounded by mature or undisturbed riparian vegetation, where higher abundances of frogs may be found in steep areas with stable patches of cobbles and boulders lying against larger stream bed elements within the stream channel. Anthropogenic activities, such as clearing or logging, and upstream disturbances that potentially increase silt input into streams were identified as threats to these frog species. Finally, the habitat-use information gathered during this investigation was utilised to develop a spatial decision support system (SDSS) as a tool to assess the quality and quantity of habitat available to L. hochstetteri populations associated with the Auckland Region. These results have important implications for the conservation of New Zealand native frog species and riparian stream habitat.