Norman Ratcliffe

British Antarctic Survey | BAS · Ecosystems Programme

Surveying seabirds in polar latitudes can be challenging due to sparse human populations, lack of infrastructure and the risk of disturbance to wildlife or damage to habitats. Counting populations using un-crewed aerial vehicles (UAVs) is a promising approach to overcoming these difficulties. However, a careful validation of the approach is needed...

The designation of Marine Protected Areas has become an important approach to conserving marine ecosystems that relies on robust information on the spatial distribution of biodiversity. We used GPS tracking data to identify marine Important Bird and Biodiversity Areas (IBAs) for the Endangered northern rockhopper penguin Eudyptes moseleyi within th...

Natural selection should favour strategies that maximise reproductive success. Females may use different resources during progressive stages of reproduction according to energetic demands, behavioural constraints and prey availability. We used South American fur seal, Arctocephalus australis australis, pup whisker isotope values as proxies for mate...

Competition for resources within a population can lead to niche partitioning between sexes, throughout ontogeny and among individuals, allowing con-specifics to co-exist. We aimed to quantify such partitioning in Antarctic fur seals, Arctocephalus gazella, breeding at South Georgia, which hosts ~95% of the world’s population. Whiskers were collecte...

Tracking individual marine predators can provide vital information to aid the identification of important activity (foraging, commuting, rafting, resting, etc.) hotspots and therefore also to delineate priority sites for conservation. However, in certain locations (e.g. Antarctica) many marine mammal or seabird colonies remain untracked due to logi...

Information is needed on how anomalous environmental conditions affect important Antarctic ecological sentinels during the winter. Using a non-invasive method (scats), the diet of non-breeding gentoo penguins Pygoscelis papua at Bird Island, South Georgia, was examined during the winter of 2009 when local environmental conditions were abnormal (e.g...

Understanding the mechanisms that link prey availability to predator behaviour and population change is central to projecting how a species may respond to future environmental pressures. We documented the behavioural responses and breeding investment of macaroni penguins Eudyptes chrysolophus across five breeding seasons where local prey density ch...

In the open ocean ecosystem, climate and anthropogenic changes have driven biological change at both ends of the food chain. Understanding how the population dynamics of pelagic predators are simultaneously influenced by nutrient-driven processes acting from the "bottom-up" and predator-driven processes acting from the "top-down" is therefore consi...

Tropical cyclones are renowned for their destructive nature and are an important feature of marine and coastal tropical ecosystems. Over the last 40 years, their intensity, frequency and tracks have changed, partly in response to ocean warming, and future predictions indicate that these trends are likely to continue with potential consequences for...

Intrapopulation variation in resource use occurs in many populations of generalist predators with important community and evolutionary implications. One of the hypothesised mechanisms for such widespread variation is ecological opportunity, i.e. resource availability determined by intrinsic constraints and extrinsic conditions. In this study, we co...

Mercury emissions have increased over the past decades affecting even remote areas such as Antarctica. As gentoo penguins (Pygoscelis papua) breed on many of the islands surrounding Antarctica, foraging close to their colonies, their mercury load should reflect concentrations in the region. We therefore evaluated mercury concentra- tions in adult g...

Feathers have been widely used to assess mercury contamination in birds as they reflect metal concentrations accumulated between successive moult periods: they are also easy to sample and have minimum impact on the study birds. Moult is considered the major pathway for mercury excretion in seabirds. Penguins are widely believed to undergo a complet...

AimTo infer the potential for competition between an important Antarctic predator, the macaroni penguin, and the krill fishery by examining the spatial overlap in prey consumption and catches.LocationScotia Sea and adjacent waters.Methods The study focused on the winter period as this is the only time of the year when spatio-temporal overlaps betwe...

The standard procedure to count birds is a manual one. However a manual bird count is a time consuming and cumbersome process, requiring several people going from nest to nest counting the birds and the clutches. High resolution imagery, generated with a UAS (Unmanned Aircraft System) offer an interesting alternative. Experiences and results of UAS...

Foraging site fidelity has profound consequences for individual fitness, population processes and the effectiveness of species conservation measures. Accordingly, quantifying site fidelity has become increasingly important in animal movement and habitat selection studies. To assess foraging site fidelity in king penguins (Aptenodytes patagonicus) b...

Predicting the future trend and viability of populations is an essential task in ecology. Because many populations respond to changing environments, uncertainty surrounding environmental responses must be incorporated into population assessments. However, understanding the effects of environmental variation on population dynamics requires informati...

Aim: Competition for food among populations of closely related species and conspecifics that occur in both sympatry and parapatry can be reduced by interspecific and intraspecific spatial segregation. According to predictions of niche partitioning, segregation is expected to occur at habitat boundaries among congeners and within habitats among con...

Understanding the demographic response of free-living animal populations to different drivers is the first step towards reliable prediction of population trends. Penguins have exhibited dramatic declines in population size, and many studies have linked this to bottom-up processes altering the abundance of prey species. The effects of individual tr...

Number of macaroni penguins PIT tagged and recaptured by season with annual population size and fecundity. Table S2. Temporal resolution of environmental covariates. Table S3. Model selection for the global model structure of age class and maximum age of transition. Table S4. Model selection, ANODEV and LRT tests for individual trait, top-down and...

We present a design for a simple, inexpensive leg band for mounting GLS tags on penguins. It causes a low level of injury and can be made from materials and tools that are readily available. We provide information on captive and field trials and outline deployment strategies that improve recovery rates. This device should facilitate further studies...

Intra-specific foraging niche partitioning can arise due to gender differences or individual specialisation in behaviour or prey selection. These may in turn be related to sexual size dimorphism or individual variation in body size through allometry. These variables are often inter-related and challenging to separate statistically. We present a cas...

The Falkland Islands currently supports one of the largest Southern Rockhopper Penguin (Eudyptes c. chrysocome) populations. Archipelago-wide censuses conducted in 2000 and 2005 revealed that the number of breeding pairs had declined by 30 % during this period. To establish whether the breeding population continued to decline, an archipelago-wide c...

Krill consumption by natural predators represents a critical link between surveys and models of standing krill biomass and the design of a sustainable krill fishery for the Scotia Sea. Antarctic krill (Euphausia superba) is a significant component of diet for penguins breeding in this region and, consequently, uncertainties regarding penguin popula...

Macaroni penguins Eudyptes chrysolophus are thought to be one of the most important mesopredators in the Southern Ocean having a greater impact on prey availability and abundance than any other seabird species. Their population centre has long been held to be South Georgia where populations were thought to comprise many million animals. Here we rep...

The impacts of predation by invasive mammals on island fauna are a major driver of insular biodiversity loss. Devastating, hitherto unsuspected impacts of predatory house mice on breeding seabirds have been described recently. We studied the fate of 178 Atlantic Petrel Pterodroma incerta nests at Gough Island, over four seasons, from October 2003 t...

[This corrects the article on p. e33751 in vol. 7.].

Our aim was to estimate the population of emperor penguins (Aptenodytes fosteri) using a single synoptic survey. We examined the whole continental coastline of Antarctica using a combination of medium resolution and Very High Resolution (VHR) satellite imagery to identify emperor penguin colony locations. Where colonies were identified, VHR imagery...

Emperor penguin colonies 2009. Size of circle relates to estimated number of pairs in each colony. (EPS)

Managing fisheries in an ecologically sensitive manner demands that catches do not depress stocks within the foraging areas used by predators to levels that reduce their reproductive success or survival. Spatially-explicit bioenergetics models that estimate the amount of prey consumed by predators are required to inform such policy. These models re...

Assessment of population size and annual breeding performance are key aspects of breeding wader research. There is however, often a trade-off between collecting highly reliable estimates of nest and chick survival at a small number of sites or less intensive monitoring of a larger number of sites giving less reliable estimates, but capturing more i...

Predation by the European starling (Sturnus vulgaris) was the main reason for roseate tern (Sterna dougallii) hatching failure on Vila islet, Azores, one of the species' largest colonies in Europe. Observations showed that single or small groups of starlings were responsible for predation events and that tern nest defence against starlings was gene...

Many of the UK’s seabird species have displayed high variation in breeding success since the 1980s, largely due to changes in the availability of Lesser Sandeels Ammodytes marinus, their main prey. During this time, Arctic Skuas Stercorarius parasiticus experienced a rapid decline in the UK and the species has subsequently been placed on the Red Li...

No abstract available.

Past studies have indicated that Pacific rats Rattus exulans are significant predators of the chicks of surface-breeding seabirds, namely gadfly petrels Pterodroma spp., on Henderson Island, central South Pacific. Further fieldwork in 2003 confirmed the heavy predation of chicks of Murphy's petrel P. ultima by rats. By extension, heavy predation is...

The introduction of mammal predators to islands often results in rapid declines in the number and range of seabirds. On Ascension Island the introduction of cats in 1815 resulted in extirpation of large seabird colonies from the main island, with relict populations of most species persisting only in cat-inaccessible locations. We describe the eradi...

The island of Mousa, Shetland, is designated as part of the European Natura 2000 reserve network as a Special Protection Area (SPA) for breeding European Storm- petrels Hydrobates pelagicus. In 1996 the population was censused using playback methods and reported as 6,800 (95% CI 4,800–8,800) apparently occupied sites (AOS), c. 26% of the UK breedin...

Rats have been introduced to islands throughout the world. They have caused breeding failures, population declines and complete extirpation of vulnerable bird species. Such impacts can be difficult to diagnose in situations where extirpation occurred prior to the vulnerable species being recorded. Mitigating the impacts of rats on seabirds depends...

Color bands and radio tags are widely used to facilitate individual recognition and relocation of precocial chicks in studies of prefledging survival. However, the accuracy of data collected and subsequent estimates of survival rates rely on the assumption that such techniques do not affect the parameters under study. We compared the body condition...

White-tailed Eagles Haliaeetus albicilla became extinct in Britain in 1918 following prolonged persecution. Intensive conservation efforts since the 1970s have included the re-introduction of the species to Britain through two phases of release of Norwegian fledglings in western Scotland in 1975–85 and 1993–98. Population growth and breeding succes...

Parsons, M., Mitchell, I., Butler, A., Ratcliffe, N., Frederiksen, M., Foster, S., and Reid, J. B. 2008. Seabirds as indicators of the marine environment. – ICES Journal of Marine Science, 65: 1520–1526. We report on the development of seabird indicators that support the Scottish Biodiversity Strategy. The application of high-quality monitoring dat...

Roseate terns are rare and restricted range breeders in NW Europe, with a population size of below 1,100 pairs and 95% of these within four colonies. The apparent survival and breeding dispersal rates of adults was estimated from live resighting data collected at three of the largest colonies between 1995 and 2007. These parameters were estimated u...

American Mink Mustela vison is a semi-aquatic predator that has invaded the west coast of Scotland and many of its associated islands. We developed a GIS model of their potential range based on their dispersal abilities and habitat use, which revealed that most islands in west Scotland are accessible to Mink, and that these host a large proportion...

The Ascension Frigatebird is an island endemic whose conservation status was subject to confusion owing to difficulties in counting and misinterpretation of data. Accurate nest counts for this species are problematic owing to their extremely prolonged breeding seasons, high nest failure rates, turnover of individuals at nest-sites, replacement layi...

Little Terns Sternula albifrons are unusual among UK seabirds in that a large proportion of the population breed on mainland beaches in East Anglia. Relative sea-level rise means that such habitats are under threat in this region, and so we quantified colony habitat selection of beach nesting Little Terns in order to inform habitat restoration and...

This report presents a novel and robust way of analysing, presenting and updating trends in populations of breeding seabirds in Scotland. This information provides a basis for one of a series of indicators of biodiversity for the Scottish Biodiversity Strategy. The analysis aims to provide a ‘state indicator,’ ie a measure of change of population...

Great Bitterns Botaurus stellaris have experienced a population decline in the UK, such that in 1997 the total number of breeding males was just 11. This study aimed to identify factors affecting productivity, and how management could be used to manipulate this. An intensive study of Great Bittern breeding success was conducted between 1997 and 200...

We examined the effect of a brood-size manipulation on the foraging effort and chick rearing of known-age great skuas Catharacta skua. Young birds were expected to refrain from increasing reproductive effort and opt for a strategy of brood reduction, while old birds were expected to increase effort and rear more young. Increasing brood size led to...

Godwits of the Limosa l. limosa race have declined throughout northern Europe because of changing agricultural practices. The relict UK population is now mostly confined to two reserves within flood‐defence structures, and numbers have declined at one of these. This study diagnosed the cause of this decline and evaluated options for remedial manage...

Skuas are top predators in marine ecosystems and may have detrimental effects on seabird communities they prey upon. However, predation rates are poorly understood and poorly quantified. Using a bio‐energetics model we estimate seabird predation by great skuas, Stercorarius skua , at a large UK colony (Hermaness, Shetland). We investigate the influ...

Age-specific variation in the reproductive performance of great skuas in Shetland, U.K., was investigated during a period of fluctuating sandeel availability between 1988 and 1993. Increased sandeel abundance was associated with earlier laying dates, increased clutch volumes and improved fledging success. Sandeel abundance had no effects on clutch...

Several different techniques have been used to study the diet composition of skuas and gulls in polar regions. In this study, we assessed the diet of great skuas using five techniques (pellets, prey remains, spontaneous regurgitates, observed feeds and water off-loading). The estimates of diet derived from each sampling technique during a single br...

The survival rates of breeding adult Great Skuas Catharacta skua were examined at Foula, the largest colony in the world, where numbers have been declining since the late 1970s. Resightings of colour-ringed breeding adults over a 12-year period were analysed using Cormack-Jolly Seber models to estimate survival rates. Annual survival rates averaged...

The Raso Lark Alauda razae is a globally endangered species that is endemic to the islet of Raso (16°93′ N, 24°38′ W) in the Cape Verde archipelago (Collar et al. 1994). Raso is a small (c.7 km ² ) uninhabited islet with a plain averaging 25 m in elevation to the south and west and small boulder-strewn hills to the north and east rising up to 164 m...

Excluding age and experience effects, individual quality is frequently assumed to be a fixed trait. This paper tests whether an individual's apparent quality, as indicated by its timing of breeding, is indeed permanent. This is assessed by studying the repeatability of laying dates of a long-lived seabird, the great skua Catharacta skua. Laying dat...

The factors affecting the probability of nest site attendance and response to playback were examined on Mousa, Shetland, during 1996 with the aim of developing a standard method of censusing Storm Petrels using diurnal playback. Nest site attendance by breeding birds peaked at 90% during July. Site attendance by non-breeding birds was much lower at...

The clutch size, a-egg volume and hatching success of Great Skuas on Foula, Shetland, were examined on successive breeding attempts following recruitment. Clutch size and a-egg volume increased with breeding experience but hatching success was not affected. The increase in clutch size was evident only between the first and second breeding attempt,...

We investigated the effect of hatching date on chick body condition, chick survival, post-fledging survival and eventual breeding performance as an adult (laying date and clutch volume) of Great Skuas in Foula (Shetland). In 10 out of 16 years there was a seasonal decline in chick body condition. In the remaining years, there was no detectable effe...