The enigma of guanacos in the Falkland Islands: the legacy of John Hamilton

Aim To address the biogeographical enigma of why guanacos (Lama guanicoe) are in the Falkland Islands we investigated the following questions: (1) What was the origin of the introduced guanacos? (2) What were the initial population sizes? (3) Why are they found only on one island? and (4) Who was John Hamilton and what role did he play? Location The Falkland Islands are located in the South Atlantic Ocean 600 km east of Patagonia at the southern end of South America. While dominated by East and West Falkland Islands, the archipelago is composed of some 750 islands. Sedge and Staats Islands, two small outlying islands of West Falkland, are the focus of this paper. Methods Historical information was collected from known relevant documents housed at the Falkland Islands Government Archives in Stanley, and personal interviews conducted with past and present residents of West Falklands. Research expeditions were made to Staats Island in 1999, 2002 and 2003 to assess the guanaco population size, distribution and social structure. Results Guanacos were unsuccessfully introduced in 1862 to East Falkland south of Mt Pleasant where Prince Alfred hunted them in 1871. John Hamilton, Scottish immigrant to the Falklands and Patagonia of southern Argentina and Chile, was the driving force in the introduction of guanacos from the region of Rio Gallegos, Argentina during the 1930s. The guanaco was one of several wildlife species he introduced, however, only the guanaco, Patagonia grey fox (Dusicyon griseus) and perhaps the sea otter (Lutra felina) survive. Hamilton's acting agent, Jimmy Miller, imported four shipments totalling 26 guanacos from 1934 to 1939. In 1934 the Falkland Government authorized Miller to introduce guanacos to Sedge Island, all 11 of which disappeared. Whether intentional or accidental, 15 guanacos were taken to Staats Island, an islet of 500 ha on the western edge of the archipelago. Historically, guanacos are unexpected on Staats Island because documentation authorizing their introduction is unknown. Guanaco numbers have fluctuated widely on Staats Island for 65 years primarily due to culling. In 1959 the population was dangerously close to extirpation, but today 400 thrive there. A severely reduced gene pool and genetic bottlenecking were suggested by recent field studies, revealing preliminary evidence of deleterious consequences of inbreeding. Main conclusions John Hamilton, spirited and visionary Scottish immigrant to the Falklands in the early 1880s, was responsible for the introduction of guanacos into the Falkland Islands. While there are some gaps in the historical events, the enigma of how and why guanacos were introduced to a single island in the South Atlantic Ocean is understood. Today, Staats Island, as a closed system, is a rare natural experiment in progress. It offers unique opportunities for addressing advanced questions in ungulate population, behavioural and genetic ecology. The population potentially also represents breeding stock for farming the guanaco's highly valuable wool on other islands. Thus, among his many efforts to practice land stewardship and promote economic diversity through the introduction of Patagonian wildlife, a remaining legacy of John Hamilton to the Falkland Islands is unmistakably the guanacos of Staats Island.     

Increasing trend in the number of Southern Rockhopper Penguins (Eudyptes c. chrysocome) breeding at the Falkland Islands

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 census was conducted in 2010. We report a conservative estimate of 319,163 ±SD 24,820 pairs breeding at the Falkland Islands in 2010. This represents a 51 % increase when compared with the number counted in 2005. A simple stochastic population model was developed to investigate the extent to which changes in demographic parameters between 2005 and 2010 could account for the increase in breeding pairs. The population model predicted a 38 % increase in the number of breeding pairs over a 5-year period (289,431 ±SD 24,615). The increase in the number of breeding pairs was therefore probably attributed to improved vital rates in the period between the 2005 and 2010 archipelago-wide censuses in combination with other factors such as a reduction in the proportion of adult birds that abstained from breeding. Based on the 2010 Falkland Islands estimate, the global population of the subspecies E. c. chrysocome is now closer to 870,000 breeding pairs of which the Falkland Islands accounts for approximately 36 %, the second largest proportion after Chile. We conclude that despite fluctuations, the number of Southern Rockhopper Penguins breeding at the Falkland Islands has increased over the last 15 years and suggest that the ‘Vulnerable’ conservation status of the species be re-assessed.     

THE AVIAN ECOLOGY OF A TUSSOCK ISLAND IN THE FALKLAND ISLANDS

In the windswept and treeless Falkland Islands, the natural vegetation has been seriously depleted by two centuries of extractive farming. One habitat—mature Tussock-grass—is of vital importance to the resident birds, and those Tussock-covered islands that remain in a nearly natural state can support a far greater density and variety of bird species than any areas on the mainland.
Kidney Island maintains a diverse avian fauna because it offers abundant cover, nest-sites, nest materials and food. In and around the dense mature Tussock-grass which covers about 90% of the surface, 28 bird species nest on the island; 18 of them occupy one or other of the six minor habitats which can be distinguished in the Tussock-grass. The nest-sites and interrelationships of these breeding species are described.     

The depth of Sooty Shearwater Ardenna grisea burrows varies with habitat and increases with competition for space

The Sooty Shearwater Ardenna grisea, an abundant but declining petrel, is one of many seabird species that construct breeding burrows, presumably because these confer protection from predators and the elements. Little is known about the causes of variation in Sooty Shearwater burrow architecture, which can differ markedly both within and between breeding sites. We hypothesize that burrow architecture varies in response to habitat type and competition for space. To address these hypotheses, we recorded Sooty Shearwater burrow dimensions on Kidney Island, the largest Sooty Shearwater colony in the Falkland Islands, South Atlantic, and modelled these as functions of burrow density (a proxy for competition) and habitat indices. Our models suggest that Sooty Shearwaters burrow further underground in response to competition for breeding space, and that soil underlying dense tussac grass Poa flabellata is more easily excavated than other substrates, indicating how vegetation restoration could aid the conservation of this species.     

Population structure of melon‐headed whales (Peponocephala electra) in the Hawaiian Archipelago: Evidence of multiple populations based on photo identification

Despite the presence of melon‐headed whales in tropical and subtropical waters worldwide, little is known about this species. To assess population structure in Hawai‘i, dedicated field efforts were undertaken from 2000 to 2009. Using only good quality photographs, there were 1,433 unique photo‐identified individuals, of which 1,046 were distinctive. Of these, 31.5% were seen more than once. Resighting data combined with social network analyses showed evidence of two populations—a smaller, resident population, seen exclusively off the northwest region of the island of Hawai‘i, and a larger population, seen throughout all the main Hawaiian Islands (hereafter the “main Hawaiian Islands” population). A Bayesian analysis examining the probability of movements of individuals between populations provided a posterior median dispersal rate of 0.0009/yr (95% CI = 0–0.0041), indicating the populations are likely demographically independent. Depth of encounters with the Hawai‘i Island resident population was significantly shallower (median = 381 m) than those with the main Hawaiian Islands population (median = 1,662 m). Resightings of individuals have occurred up to 22 yr apart for the Hawai‘i Island resident population and up to 13 yr apart for the main Hawaiian Islands population, suggesting long‐term residency to the islands for both populations.     

Geographical variation in egg size dimorphism in rockhopper penguins

All crested penguins present a unique reversed hatching asynchrony: the larger second-laid egg (B-egg) hatches before the smaller first-laid egg (A-egg). Although both eggs often hatch, the A-chick generally dies of starvation within days after hatching. However, within rockhopper penguins, the population at the Falkland Islands is unique in that some birds manage to raise both chicks. Although it has been suggested that the egg size dimorphism between A- and B-eggs may explain how long both eggs and chicks survive, this hypothesis has never been explicitly tested. We expect that both eggs are retained longer in the less dimorphic clutches than in the more dimorphic ones. In this paper, we have compiled egg measurements for three rockhopper penguin species (Eudyptes chrysocome, E. filholi and E. moseleyi) in order to compare the intra-clutch egg size dimorphism among these species. Furthermore, we have collected new data to compare egg size dimorphism between two populations of E. chrysocome (Falkland Islands versus Staten Island). A-egg volumes are more variable between species and populations than B-egg volumes. E. chrysocome and especially the population from the Falkland Islands produces the largest A-eggs and the least dimorphic eggs. Nevertheless, as differences in A-egg volumes between species and between the populations of Falkland Islands and Staten Island are stronger and more significant than differences in egg dimorphism, we suggest that A-egg volume, more than egg dimorphism, could be one of the factors influencing the prevalence of twins. A large A-egg and/or reduced egg dimorphism is probably necessary to enable rockhopper penguins to raise two chicks, but other reasons may also be involved which enable them to keep both eggs and chicks.     

Grasshopper outbreak challenges conservation status of a small Hawaiian Island

A tiny (63.1 ha) and uninhabited Nihoa Island within the Hawaiian Archipelago is situated 250 km NW of Kauai. It is a part of Papahānaumokuākea National Marine Monument established in 2006 and jointly administered by NOAA, USFWS, and the State of Hawaii (Department of Land and Natural Resources). The island’s known terrestrial biota include 26 vascular plant species, 27 bird species, and 243 arthropod species. Approximately half of the species are endemic to Nihoa or indigenous to Hawaii. Four plant species and two resident bird species are federally listed as threatened or endangered species. Gray bird grasshopper Schistocerca nitens has occurred on the main Hawaiian Islands since 1964 and was first reported from Nihoa in 1977. In 2002–2004, there was an outbreak of this grasshopper that aggravated the drought and denuded most of the island’s vegetation. Since then, grasshopper numbers crashed, most probably due to insufficient soil moisture for embryonic development. With subsequent rains, the island’s vegetation recovered. During the USFWS expedition to Nihoa in October 2006, grasshopper population assessments were undertaken. Based on 18, 300 × 2 m transect counts, the Nihoa grasshopper population was estimated at 19,430 ± 10,360 individuals. Laboratory rearing of S. nitens revealed that its development occurs without diapause. Potentially, the grasshopper can produce as many as four annual generations on Nihoa, although it is likely that only two generations occur. This article reviews the implications of fluctuations in S. nitens population dynamics for island flora and entomo- and avifauna, in particular, for the endangered endemics, the insectivorous Millerbirds. Potential threats to the island’s biota and challenges for conservation are discussed.     

External nutrient inputs into terrestrial ecosystems of the Falkland Islands and the Maritime Antarctic region

Antarctic terrestrial ecosystems are nutrient-poor and depend for their functioning in part on external nutrients. However, little is known about the relative importance of various sources. We measured external mineral nutrient sources (wind blown material, precipitation and guano) at three locations, the cold temperate oceanic Falkland Islands (51°76′S), and the Maritime Antarctic Signy (60°71′S) and Anchorage Islands (67°61′S). These islands differ in the level of vegetation development through different environmental constraints and historical factors. Total mineral nitrogen input differed considerably between the islands. During the 3 month summer period it amounted to 18 mg N m⁻² on the Falkland Islands and 6 and 102 mg N m⁻² at Signy and Anchorage Islands, respectively. The high value for Anchorage was a result of guano deposition. By measuring stable isotopic composition (δ¹⁵N) of the different nitrogen sources and the dominant plant species, we investigated the relative utilisation of each source by the vegetation at each island. We conclude that external mineral nitrogen inputs to Antarctic terrestrial ecosystems show great spatial variability, with the local presence of bird (or other vertebrate) colonies being particularly significant.     

Multiple losses of flight and recent speciation in steamer ducks

Steamer ducks (Tachyeres) comprise four species, three of which are flightless. The flightless species are believed to have diverged from a flying common ancestor during the Late Pleistocene; however, their taxonomy remains contentious. Of particular interest is the previously unstudied population of flying steamer ducks in the Falkland Islands. We present the first genetic data from this insular population, and illustrate that the flying and flightless steamer ducks on the Falkland Islands are genetically indistinguishable, in contrast to their traditional classification as separate species. The three species that reside in continental South America form a genetically distinct lineage from the Falkland Island ducks. The Falkland steamer ducks diverged from their continental relatives 2.2-0.6 million years ago, coincident with a probable land bridge connecting the Falkland Islands to the mainland. The three continental species share a common ancestor approximately 15 000 years ago, possibly owing to isolation during a recent glacial advance. The continental steamer duck species are not reciprocally monophyletic, but show some amount of genetic differentiation between them. Each lineage of Tachyeres represents a different stage between flight and flightlessness. Their phylogenetic relationships suggest multiple losses of flight and/or long-term persistence of mixed-flight capability. As such, steamer ducks may provide a model system to study the evolution of flightlessness.     

Demographic parameters of black-browed albatrosses Thalassarche melanophris from the Falkland Islands

Black-browed albatrosses Thalassarche melanophris are currently classified as globally endangered. The most important populations of this species are believed to be declining due to, amongst other factors, unsustainable levels of incidental mortality in fishing gear. However, detailed demographic data are lacking for several critical populations, including the largest of all, nesting in the Falkland Islands. Here, we present data from the first Falkland Islands detailed demographic study (at New Island) and show that, from 2003 to 2009, the mean adult survival probability was 0.942 (95% CI: 0.930–0.952). Nesting frequency of adults is amongst the highest recorded for Thalassarche albatrosses and breeding success (0.564 chicks per egg) is within normal values. The nesting population in the intensively studied plots experienced an increase of 4% per year from 2004 to 2009. These results indicate that the Falklands population may not be as threatened as previously supposed, although studies from more sites and a longer time series are needed to confirm or refute this. The high survival rates may partly reflect recent efforts to mitigate bycatch made by the Falkland Islands and other fisheries in the region. The reinforcement of such initiatives may be critical to buffer the black-browed albatross population against ecosystem shifts and natural disasters (such as harmful algal blooms) that will likely become more frequent with ongoing global changes.     

Winter ecology of house mice and the prospects for their eradication from Steeple Jason (Falkland Islands)

Invasive house mice Mus musculus are known to impact on seabird, invertebrate and plant communities on temperate and subantarctic islands, particularly where they are the sole rodent species. Steeple Jason, in the Falkland Islands, is an island which supports globally important seabird populations as well as introduced mice. To evaluate the prospects for mouse eradication, we investigated mouse ecology and undertook bait uptake trials on Steeple Jason in late winter. Mice were present in all habitats but were most abundant in tussac Poa flabellata where they occurred at 20–35 mice ha^?1. From 58 mature perforate females, 16 % were pregnant, with litters of 4–8 pups. The first lactating female was caught at the end of August, suggesting that breeding had recently begun. Bait trials replicating an aerial eradication were undertaken on two trapping grids of 7.7 and 6.8 ha, with non-toxic pellets containing the biomarker pyranine spread at 7.5–7.7 kg ha^?1. All 447 mice captured after baiting had consumed bait. The relatively low winter density, distribution and biology of house mice on Steeple Jason are similar to those observed before other successful mice eradications, and the study indicated 100 % bait acceptance. Before an eradication attempt, we suggest investigating whether breeding ceases completely earlier in the winter and urge careful consideration of non-target species.     

Terrestrial fauna survey of Slipper Island (Whakahau)

We describe the history of Slipper Island (Whakahau) off northeastern New Zealand and report on a survey of the terrestrial fauna undertaken in December 2016. Results from this survey are compared with the last comprehensive survey in August 1973. The terrestrial habitat of the island is predominantly farmland and has changed little in extent over the past 50 years. As a result, the avifauna has remained remarkably consistent, although with some species turnover that reflects changes in the wider regional landscape, and some notable native species additions. Pacific rats were abundant across the island, and as a result reptiles are depauperate due to local extinctions. Bell frogs and Argentine ants are both recent arrivals on the island. On the nearby smaller native forested Penguin and Rabbit Islands the avifauna is predominantly native.     

Exploratory deep-sea fishing in the Falkland Islands, south-western Atlantic

Records of demersal deep-sea fish assemblages in waters around the Falkland Islands (Patagonian shelf area) are rare. Twenty deep-water stations to the east and south of the Falkland Islands were sampled by commercial bottom trawl deployed in upper, middle and lower benthopelagic zones (depth range of approximately 500-1000 m). Forty-one species (22 families) of teleost fish were recorded, 10 species (two families) of elasmobranch and one species of agnathan. Different assemblages of fish were found to characterize each depth zone (e.g. Moridae in deeper waters, Bothidae and Rajidae in shallower waters), with diversity being greatest in the mid-zone and biomass greatest in the upper and lower zones. Some species occurred in all zones but showed depth-related abundance. Four species, namely the grenadiers Macrourus carinutus and Coelorhynchus fasciatus , the southern blue whiting Micromesistius australis , and the Patagonian toothfish Dissostichus eleginoides , accounted for 85% by weight of all fish caught. Quantitative sampling of selected species revealed depth-related variations in their population structure. Length-frequency analyses are presented for M. carinatus and D. eleginoides and show a tendency for larger individuals to inhabit deeper water. Discard rates from the commercial catch were sometimes high, particularly for the smaller species, raising concerns about the impact of a fishery on by-catch species. The potential for deep-sea fisheries in Falkland waters is discussed and further studies are suggested in the light of developing oil, gas and fishing industries. The presence of some invertebrate taxa is recorded.     

Preliminary stock assessment of the Patagonian toothfish longline fishery around the Falkland Islands

An experimental fishery for Patagonian toothfish Dissostichus eleginoides was opened in Falkland Island waters briefly in 1992 and then from April 1994. One to two longlines per vessel were usually deployed at night, mostly fishing for 12–30 h at depths between 600 and 2000 m. The characteristics of the vessel, gear, fishing activities and the data collection and analyses methods are described. An initial evaluation of the authors' current understanding of toothfish biology and population dynamics in Falkland Island waters is given. A first analysis of toothfish numbers caught in 1994 suggests that these are changing at rates faster than expected from simple demographic processes. Therefore, despite an intensive monitoring of catch and fishing effort of each vessel, it is still not possible to derive reliable estimates for the size of the toothfish population currently exploited around the Falkland Islands. Migration patterns in and out of the fishery need to be understood before a reliable assessment of the fishery can be made. These results, together with current and future lines of research, are discussed in the light of data available from other toothfish fisheries in austral waters.     

Evolutionary ecomorphology of the Falkland Islands wolf Dusicyon australis

The Falkland Islands wolf Dusicyon australis is an extinct canid that was once the only endemic terrestrial mammal to inhabit the Falkland Islands. There is still a puzzling picture of the morphological adaptations of this wolf that quickly evolved from its mainland fossil ancestor: Dusicyon avus. We employ a geometric morphometric approach to identify patterns of skull shape variation in extant canids and Dusicyon spp. The Falkland Islands wolf and its fossil ancestor show a more carnivorous feeding morphology than other South American foxes, and they cluster morphologically with jackals. This supports convergence in skull shape between Dusicyon and Old World canids, although the convergence is not as strong as that exhibited by their sister hyper‐ and hypocarnivorous taxa.     

Fine-scale population genetic structure of a wildlife disease vector: the southern house mosquito on the island of Hawaii

The southern house mosquito, Culex quinquefasciatus, is a widespread tropical and subtropical disease vector. In the Hawaiian Islands, where it was introduced accidentally almost two centuries ago, it is considered the primary vector of avian malaria and pox. Avian malaria in particular has contributed to the extinction and endangerment of Hawaii's native avifauna, and has altered the altitudinal distribution of native bird populations. We examined the population genetic structure of Cx. quinquefasciatus on the island of Hawaii at a smaller spatial scale than has previously been attempted, with particular emphasis on the effects of elevation on population genetic structure. We found significant genetic differentiation among populations and patterns of isolation by distance within the island. Elevation per se did not have a limiting effect on gene flow; however, there was significantly lower genetic diversity among populations at mid elevations compared to those at low elevations. A recent sample taken from just above the predicted upper altitudinal distribution of Cx. quinquefasciatus on the island of Hawaii was confirmed as being a temporary summer population and appeared to consist of individuals from more than one source population. Our results indicate effects of elevation gradients on genetic structure that are consistent with known effects of elevation on population dynamics of this disease vector.     

Post-Fledging Dispersal of King Penguins (Aptenodytes patagonicus) from Two Breeding Sites in the South Atlantic

Most studies concerning the foraging ecology of marine vertebrates are limited to breeding adults, although other life history stages might comprise half the total population. For penguins, little is known about juvenile dispersal, a period when individuals may be susceptible to increased mortality given their naïve foraging behaviour. Therefore, we used satellite telemetry to study king penguin fledglings (n = 18) from two sites in the Southwest Atlantic in December 2007. The two sites differed with respect to climate and proximity to the Antarctic Polar Front (APF), a key oceanographic feature generally thought to be important for king penguin foraging success. Accordingly, birds from both sites foraged predominantly in the vicinity of the APF. Eight king penguins were tracked for periods greater than 120 days; seven of these (three from the Falkland Islands and four from South Georgia) migrated into the Pacific. Only one bird from the Falkland Islands moved into the Indian Ocean, visiting the northern limit of the winter pack-ice. Three others from the Falkland Islands migrated to the eastern coast of Tierra del Fuego before travelling south. Derived tracking parameters describing their migratory behaviour showed no significant differences between sites. Nevertheless, generalized linear habitat modelling revealed that juveniles from the Falkland Islands spent more time in comparatively shallow waters with low sea surface temperature, sea surface height and chlorophyll variability. Birds from South Georgia spent more time in deeper waters with low sea surface temperature and sea surface height, but high concentrations of chlorophyll. Our results indicate that inexperienced king penguins, irrespective of the location of their natal site in relation to the position of the APF, develop their foraging skills progressively over time, including specific adaptations to the environment around their prospective breeding site.     

Distribution and reproduction of the Patagonian toothfish Dissostichus eleginoides Smitt around the Falkland Islands

Population characteristics of the Patagonian toothfish Dissostichus eleginoides were investigated based on material collected from both trawl and longline fisheries in Falkland Islands' waters. The fish occurred between 56 and 2122 m and attained 225 cm total length ( L _T). Males matured earlier, L _T at 50% maturity was 86 cm for males v . 90 cm for females. Subadult fish foraged at depths of <600 m, whereas adult Patagonian toothfish lived at >600 m. Spawning occurred on slopes of the Burdwood Bank at c . 1000 m depth with a minor peak in May, and a major peak in July to August. Males arrived at the spawning grounds first. Between spawning peaks both sexes remained around the Burdwood Bank with males occurring at greater depths than females. The Patagonian toothfish in south‐east Patagonia and the Falkland Islands had a long juvenile and sub‐adult period in the relatively shallow and warm waters of the outer shelf and upper slope unlike that of juveniles in other Patagonian toothfish populations. The migratory life style of the south‐west Atlantic population is probably very different from that of other populations, which tend to be resident as they are inclined to inhabit the waters around oceanic islands and sea mounts with narrow shelf areas.     

Demographic variations in the movements of Upland geese Chloëphaga picta and Ruddy-headed geese Chloëphaga rubidiceps in the Falkland Islands

Recoveries and sight-records were made from 2700 Upland and 470 Ruddy-headed geese marked in the Falkland Islands between 1977 and 1980 in order to describe the movements of these island populations. First-year male Upland geese tended to be sighted further from natal areas than first-year females, once independent of their parents. Second-year Upland geese were sighted further from shedding sites than adults throughout the year. This age-related difference was also found for Ruddy-headed geese in spring. Breeding adults of both species were rarely sighted more than 5 km from their territories. Upland adults moved furthest from their breeding territory during Sate summer and autumn. Significantly more long-distance (over 20 km) movements were recorded for Ruddy-headed geese compared with Upland geese, and were mostly carried out by geese in their second or third year, for both species. The mobility of the geese makes attempts to reduce the population on certain pastures by culling ineffective.     

Climate as a driver of population variability in breeding Gentoo Penguins Pygoscelis papua at the Falkland Islands

Detecting and predicting how populations respond to environmental variability are eminent challenges in conservation research and management. This is particularly true for wildlife populations at high latitudes, many of which demonstrate changes in population dynamics associated with global warming. The Falkland Islands (Southwest Atlantic) hold one of the largest Gentoo Penguin Pygoscelis papua populations in the world, representing c. 34% of the global population. The numbers of breeding Gentoo Penguins at the Falkland Islands have shown a high degree of inter‐annual variability since monitoring commenced in 1990. However, proximate causes of annual variability in breeding numbers have not been explored. Here we examine 21 years of Gentoo Penguin breeding surveys from the Falkland Islands and assess whether inter‐annual variability in the number of breeding pairs were correlated with proxies of environmental variability. There was a positive correlation between the number of breeding pairs and a broad‐scale climatic variation index, the Southern Oscillation Index (SOI). In turn, the SOI was significantly correlated with spring sea surface temperature anomalies, indicating a more immediate atmospherically forced response to El Niño Southern Oscillation variability in the Southwest Atlantic than previously reported. However, we also describe a non‐linear response to environmental variability that may highlight foraging plasticity and/or the complexity of regional ecosystem interactions that operate across a range of different scales.