Pluvialis Squatarola Research Articles

Habitat Choice and Niche Characteristics Under Poor Food Conditions. A Study on Migratory Nearctic Shorebirds in the Intertidal Flats of Brazil

The tidal flats of the Bragantinian Peninsula in the tropical part of Brazil harbour wintering and migratory nearctic shorebirds in very high densities, whereas the benthic food supply is very low. In 2001 and 2002 a study was conducted on the habitat choice and distribution of shorebirds to investigate the formation of niches and the spatial distribution under the constraint of a limited food supply. We showed that shorebird densities were not correlated with a range of abiotic variables or with prey density within sites, but that between sites birds tended to select sites with peak prey densities. Two foraging guilds were differentiated: Whimbrel Numenius phaeopus, Willet Tringa semipalmata and Short-billed Dowitcher Limnodromus griseus preferred to forage in the water or on wet sand at the water's edge; while Red Knot Calidris canutus, Grey Plover Pluvialis squatarola, Ruddy Turnstone Arenaria interpres, Semipalmated Sandpiper Calidris pusilla and Semipalmated Plover Charadrius semipalmatus, were found predominantly on dry substrate. Although the birds showed species-specific preferences for characteristics defining microhabitats, niches were broadly overlapping. The results of our study suggest that, in case of a very low food supply, individuals might not be able to react to competition by niche segregation but might be forced to feed in a broad range of available niches.

Biodiversity of birds of 13 de julho avenue mangrove in Aracaju, Sergipe

One agreed to use the denomination 13 de Julho-Atalaia mangrove the mangrove extension of 13 de Julho up to the Districtof Atalaia, Aracaju (SE). In this study area, 6 fixed points were established, of which we did the identification and the counting of thenumber of individuals of each species and the characterization of the type of activity they engage in. From July 2003 to July 2004 atotal of 44 observation journeys were carried out with a minimum duration of 1 hour and a maximal of 4 hours and 20 minutes (meanduration ±2 2 h 36 m). We identified 19 families and 46 birds species, being that 17 of these were migrant coming from the Northhemisphere. Among the observed migrant species four belonged to the Charadriidae family: Charadrius semipalmatus, Charadriuswilsonia, Pluvialis squatarola, Pluvialis dominica; eleven to Scolopacidae: Calidris alba, Calidris pusilla, Calidris fuscicollis, Calidriscanutus, Arenaria interpres Numenius phaeopus, Tringa flavipes, Tringa melanoleuca, Actitis macularia, Catoptrophorus semipalmatus,Limnodromus griseus. Ardeidaes observed in mangroves can be considered residents, in spite of the variations presented by some speciessuch as Egretta thula, Florida caerulea, Casmerodius albus, Butorides striatus, Nyctanassa violaceus and Bubucus ibis.

The energetic importance of night foraging for waders wintering in a temperate estuary

Many species of waders forage extensively at night, but there is very little information on the relevance of this behaviour for the energy budget of waders wintering in estuarine wetlands. Quantitative data on diurnal and nocturnal intake rates can indicate the extent to which birds need to forage at night to supplement their diurnal energetic intake, or rather show a preference for nocturnal foraging. We compared day and night foraging behaviour, diet, and energy consumption of several wader species in the Tejo estuary, Portugal. There were significant differences between diurnal and nocturnal foraging behaviour. In general, birds moved less at night and scolopacid waders tended to use more tactile foraging methods. Although birds consumed the same type of prey in the two periods, the relative importance of each type changed. Overall, energy consumption was higher during the day except in grey plover, which achieved higher crude intake rates at night. Our results support the assertion that night foraging is an important part of the energy balance of waders during late winter, but that in most species it is less profitable than diurnal foraging.

Shorebird Use of Sandy Beaches in Central California

In this study, the relationship between physical attributes of sandy beaches, levels of human disturbance, and shorebird occurrence was investigated. The linear density km-1 of shorebirds on 42 km of sandy beaches in Monterey Bay, California was documented from late autumn through spring, and the relationship of shorebird densities to two physical variables (slope of beach swash zone, total beach width), one spatial variable (distance to Elkhorn Slough, a wetland of regional importance for shorebirds), and relative level of human disturbance was analyzed using stepwise multiple regression. The six most abundant species were Sanderling (Calidris alba), Willet (Tringa semipalmata), Marbled Godwit (Limosa fedoa), Black-bellied Plover (Pluvialis squatarola), Whimbrel (Numenius phaeopus) and Snowy Plover (Charadrius alexandrinus). Mean abundance of four of the six most abundant species (Marbled Godwit, Willet, Whimbrel, Black-bellied Plover) was negatively related to swash zone slope; flatter beaches supported more shorebirds. Mean abundance of all species analyzed was negatively related to distance to Elkhorn Slough; beaches closer to the mouth of Elkhorn Slough supported more shorebirds. Total beach width had no effect on shorebird occurrence, and level of human use appeared to have no effect. Most shorebird species were more abundant on beaches at low than at high tide, indicating that sandy beaches provide important foraging habitat regionally.

A review of agricultural land use by shorebirds with special reference to habitat conservation in the Fraser River Delta, British Columbia

Many estuaries worldwide are important habitats for shorebirds. Agricultural fields adjacent to food-rich intertidal areas can provide roosting and feeding habitat, particularly at high tide. The Fraser River Delta (FRD) contains rich agricultural land and is Canada’s most important non-breeding site for shorebirds. We review and synthesize recent studies that have investigated agricultural land as non-breeding habitat for shorebirds in the FRD using radio-tracking, day-time and night-time surveys, stable isotope analysis of blood samples, examination of prey in stomach and faecal samples, and farmer surveys regarding field management. The three primary shorebirds studied in the FRD were dunlin (Calidris alpina pacifica), black-bellied plover (Pluvialis squatarola), and killdeer (Charadrius vociferus). Field use is mainly nocturnal for dunlin, but diurnal for black-bellied plovers and killdeer. Dunlin and black-bellied plovers mainly use bare or winter cover crop fields, preferring short cover. Killdeer mainly use berry and winter vegetable fields. All species prefer fields recently manured, fertilized, or laser levelled. Day length and precipitation influenced field use. Stable isotope analysis (δ13C, δ 15N) of dunlin blood indicates that approximately 38% of dunlin diet is obtained from agricultural habitat. Younger birds have a higher terrestrial contribution to diet (~43%) than adults (~35%). Dunlin prey includes agricultural pest species such as leatherjacket (Tipulidae) larvae and wireworm (Agriotes spp.). Coastal agricultural land with diverse crop types benefits shorebirds, and its loss may negatively impact fitness, especially for juveniles. Research conducted in the FRD shows the importance of farmland for wintering shorebirds and suggests conservation and management strategies to preserve and enhance the wildlife value of this agricultural habitat. Key words: Farmland, agricultural land, shorebirds, Fraser River Delta, management, wildlife conservation

Factors influencing farmland habitat use by shorebirds wintering in the Fraser River Delta, Canada

Like many other coastal regions of the world, open-soil agricultural lands in the Fraser River Delta provide roosting and feeding habitat for non-breeding shorebirds that supplements intertidal habitat. Focusing on dunlin ( Calidris alpina pacifica), black-bellied plover ( Pluvialis squatorola), killdeer ( Charadrius vociferus), and their avian predators (raptors), diurnal and nocturnal high tide surveys were conducted across the non-breeding period, October–April (1998–2000). All three shorebirds showed positive relationships with laser leveling, and recent manure and fertilizer application. Day length was negatively related to field use by dunlin, but positively related for black-bellied plover and killdeer. Amount of recent precipitation was positively related to dunlin and negatively related to black-bellied plover and killdeer field use. Results suggest that providing a mosaic of different crop types, autumn mowing, laser leveling, application of fertilizer and manure, and minimizing habitat fragmentation through maintenance of large fields are habitat management strategies that may enhance farmland for shorebirds during the non-breeding season in this region.

Use of Willapa Bay, Washington, by shorebirds and waterfowl after Spartina control efforts

ABSTRACT Over the past 15 yr, an invasive cordgrass, Spartina alterniflora, has covered more than 5000 ha of tidal mudflats in Willapa Bay, Washington, threatening key shorebird habitat on the Pacific Flyway. Although chemical and mechanical control methods have been used to manage Spartina in Willapa Bay, little is known about how these methods affect subsequent use by shorebirds and waterfowl. During 2003–2004, four sites were monitored for 10-min periods for use by shorebirds [Dunlin (Calidris alpina), Western Sandpiper (C. mauri), Least Sandpiper (C. minutilla), Black-bellied Plovers (Pluvialis squatarola) and Long-billed and Short-billed dowitchers (Limnodromus sp.)] and waterfowl [Mallard (Anas platyrhynchos), Gadwall (A. strepera), American Wigeon (A. americana), Green-winged Teal (A. crecca), and Canada Goose (Branta canadensis)]. The four sites were bare mudflat (never infested with Spartina), tilled Spartina meadow (free of live Spartina and dead stubble), herbicide-sprayed Spartina meadow (10% living Spartina and 30% dead stubble), and an untreated Spartina meadow. Untreated Spartina meadow was rarely used by birds, with a mean of seven small Calidris sandpipers (peeps) and 0.8 waterfowl ha−1. Mean numbers of peeps and waterfowl observed using the herbicide-treated Spartina meadow were 62 and 16 ha−1, and the tilled Spartina meadow were 700 and 27 ha−1, respectively. Mean use of the adjacent bare mud site by peeps and waterfowl was 450 and 11 ha−1, respectively. The untreated Spartina meadow, sprayed meadow, tilled meadow and the bare mud site had mean densities of Black-bellied Plovers and dowitchers of 26, 24, 6, and 0 ha−1, and 0.8, 6, 0.3, and 0 ha−1, respectively. Our results demonstrate that, within several years of removal of invasive Spartina from mudflats in a large Washington estuary by either mechanical or chemical means, use by shorebirds and waterfowl will increase dramatically.

Structural Identification of the β-Hydroxy Fatty Acid-Based Diester Preen Gland Waxes of Shorebirds

The intact C33-C52 diester wax esters of the preen gland of the shorebirds Limosa lapponica, Pluvialis squatarola, and Pluvialis fulva were determined, using synthesized standards, to comprise predominantly C12-C16 beta-hydroxy fatty acids esterified with a C8-C18 fatty acid at the beta-hydroxy position and with predominantly C12-C20 fatty alcohols esterified at the carboxyl group.

Behavioural Plasticity in Foraging Mode of Typical Plovers

The foraging behaviour of typical plovers is highly stereotyped, and short-billed plovers all forage visually in a run—stop—search manner. To date, the use of a sandpiper-like foraging method by typical plovers is considered anecdotal in non-breeding plovers, since only one study has described Grey Plovers Pluvialis squatarola foraging as sandpipers do, striding slowly and pecking at the water surface during short periods. We studied the behaviour and intake rate of Grey and Ringed Plovers Charadrius hiaticula foraging like sandpipers on suspended prey items in the water column of hypersaline pans, and investigated factors that may influence their occurrence. The feeding rate was 48.9 ± 18.0 (SD) and 19.1 ± 6.3 prey min-1 for Ringed and Grey Plover, respectively. For Ringed Plovers, the net intake rate was 0.23 ±0.05 kJ min-1, and for Grey Plovers 0.09 ± 0.01 kJ min-1. The sandpiper-like foraging method was particularly important for Ringed Plovers, since up to 24% of the population foraged in this way at high tide. We found that the sandpiper-like foraging method is a common foraging method in Ringed Plover feeding in prey-abundant pans and is occasionally used by Grey Plovers as well. We showed that behavioural plasticity in foraging methods of typical plovers may be greater than has been assumed previously. These results suggest that typical plovers can successfully locate and capture small prey items while walking continuously and without the need to stop to improve visual acuity.

The spring migration of Grey Plover Pluvialis squatarola in Sweden

In 1976—1995, 74,650 Grey Plovers Pluvialis squatarola were recorded on spring passage, 87% in the southern third of Sweden, and 59% while in migratory flight. Few were observed before May. The passage peaked 24 May—2 June (83%). About one fourth of all birds were observed on a few occasions, when grounded by inclement weather, showing that only a tiny fraction stops over regularly. In northern Sweden, passage peaked earlier (18 May) than in the south (29 May), and these early birds were presumably destined for breeding or staging in the White Sea region. The peak dates in southern Sweden correlate well with arrival time in Siberia, indicating a non-stop flight to these breeding areas. Flocks counted up to several hundred birds in the south but at most 34 birds in the north. Migration patterns along the East Atlantic Flyway were similar with those of the East African/ West Asian and Mediterranian/Black Sea flyways. The spring passage of the Grey Plover conforms to the migration system of other tundra waders passing up through the western Palaearctic.

Effect of Beach Replenishment Projects on Waterbird and Shorebird Communities

Abstract In an effort to identify the potential effects of beach replenishment projects on waterbird and shorebird communities, avian abundance, species richness, and behavior were monitored at three transects before and after beach replenishment. The length of the study was 2 years with weekly surveys for most of the year. Data were analyzed with a Before/After Control Impact Pairs (BACIP) design, which incorporated spatial and temporal data from a control beach and replenished beaches into one analysis. No significant changes in mean waterbird and shorebird abundance were detected after replenishment, although the data do suggest that habitat use by waterbirds might have increased at replenished beaches. Of the individual waterbird and shorebird species examined, only Laughing Gulls and Black-bellied Plovers exhibited a significant change in abundance after replenishment, with these species exhibiting an increase and a decrease, respectively. Postreplenishment changes in waterbird and shorebird species ...

Nereidid Polychaetes as the Major Diet of Migratory Shorebirds on the Estuarine Tidal Flats at Fujimae-Higata in Japan

The dietary items of five migratory shorebirds, Dunlin (Calidris alpina), Red-necked Stint (C. ruficollis), Grey Plover (Pluvialis squatarola), Whimbrel (Numenius phaeopus) and Black-headed Gull (Larus ridibundus), were examined by analyses of fecal droppings during the birds' migration or wintering and by surveys of macrobenthic fauna around their foraging sites on the tidal flats of Fujimae-higata, Nagoya, central Japan. Body parts of nereidid, capitellid, and spionid polychaetes and crustaceans were found in fecal droppings from all of these shorebirds. Two nereidid species (Hediste diadroma and Neanthes succinea) with relatively large body sizes seemed to be the majority dietary items. At one site, H. diadroma was dominant in terms of biomass (40-370 g/m(2)) throughout year except, for less than 1 g/m(2) in March and May (within or just after reproduction of this species). Monthly changes in the occurrence of food items in fecal droppings of C. alpina were examined in 1999 and 2000. Most (85-100%) of the fecal droppings contained nereidid body parts, including Hediste-specific simple chaetae from November to April, whereas only 23% of the droppings contained them in May. Chaetae of capitellid or spionid polychaetes were frequently found from January to April (38-86% of droppings). Crustacean body parts, including amphipod appendages, were frequently found from March to May (86-100% of droppings). The relationship between foraging habits of the shorebirds and the life history of their major prey nereidid species is discussed.

Analysing Faecal Samples of Ragworm Predators: Not Just a Matter of Counting Mandibles

Ragworms Hediste diversicolor are an important prey item in the diet of many estuary birds. The standard method for estimating the number of Ragworms in faeces or pellets is simply dividing the counted number of Ragworm mandibles by two, which can easily lead to an underestimation of the real number of Ragworms present. Here, I present two alternative methods, which avoids bias in estimates of the number of Ragworms in samples. I compared the three methods by applying them to faecal samples of Grey Plover Pluvialis squatarola and Redshank Tringa totanus from the Tagus estuary, Portugal. The alternative methods yielded significantly higher estimates of the number of Ragworms present in each sample, a difference that can have repercussions on the outcome of dietary studies of Ragworm predators. The pros and cons of each method are discussed with regard to the use of faeces and pellets for ecological research, and the situation in which each method could be applied is discussed.

Effects of Nest Habitat, Food, and Parental Behavior on Shorebird Nest Success

AbstractAbstractIn environments such as arctic tundra, where bird densities are low and habitats are comparatively homogeneous, suitable nest sites likely are not limited. Under these conditions, reproductive success of birds may be determined by factors other than the habitat characteristics of nest sites. We studied the relative influence of nest habitat, food, nest distribution, and parental behavior on the reproductive success of tundra-breeding shorebirds at East Bay, Southampton Island, Nunavut, Canada. From 2000 to 2002, we monitored the nests of five species: Black-bellied Plover (Pluvialis squatarola), Semipalmated Plover (Charadrius semipalmatus), Ruddy Turnstone (Arenaria interpres), White-rumped Sandpiper (Calidris fuscicollis), and Red Phalarope (Phalaropus fulicarius). For each species, habitat differed between nest sites and random sites. In contrast, habitat differed between successful and failed nest sites only for White-rumped Sandpipers. Shorebirds did not prefer to nest in habitats where food was most abundant. Although nest success varied among species in all years, artificial nest experiments suggested that interspecific variation in predation rate was not related to habitat type. Instead, the marked interspecific variation in nest success may have been related to incubation behavior. Species taking fewer incubation recesses had higher nest success, although these results should be viewed as preliminary. The factor with the greatest interannual influence on nest success was fluctuating predation pressure, apparently related to the abundance of predators and lemmings.

EFFECTS OF NEST HABITAT, FOOD, AND PARENTAL BEHAVIOR ON SHOREBIRD NEST SUCCESS

Abstract ABSTRACT In environments such as arctic tundra, where bird densities are low and habitats are comparatively homogeneous, suitable nest sites likely are not limited. Under these conditions, reproductive success of birds may be determined by factors other than the habitat characteristics of nest sites. We studied the relative influence of nest habitat, food, nest distribution, and parental behavior on the reproductive success of tundra-breeding shorebirds at East Bay, Southampton Island, Nunavut, Canada. From 2000 to 2002, we monitored the nests of five species: Black-bellied Plover (Pluvialis squatarola), Semipalmated Plover (Charadrius semipalmatus), Ruddy Turnstone (Arenaria interpres), White-rumped Sandpiper (Calidris fuscicollis), and Red Phalarope (Phalaropus fulicarius). For each species, habitat differed between nest sites and random sites. In contrast, habitat differed between successful and failed nest sites only for White-rumped Sandpipers. Shorebirds did not prefer to nest in habitats w...

Utility of ITS1–5.8S–ITS2 and 16S mitochondrial DNA sequences for species identification and phylogenetic inference within the Rhinonyssus coniventris species complex (Acari: Rhinonyssidae)

The complete internal transcribed spacer 1 (ITS1), 5.8S rDNA, and ITS2 region of the ribosomal DNA and a 390-bp region of the 16S rDNA gene from five taxa belonging to Rhinonyssus (Rhinonyssus vanellus, Rhinonyssus tringae, Rhinonyssus neglectus, Rhinonyssus echinipes from Kentish plover, and Rhinonyssus echinipes from grey plover) were sequenced to examine the level of sequence variation and the taxonomic levels to show utility in phylogeny estimation. Our data show that these molecular markers can help to discriminate between species and populations included in the Rhinonyssus coniventris complex (R. tringae, R. neglectus, R. echinipes), which are morphologically very close and difficult to separate by classic methods. A comparative study with sequences from other rhinonyssid mites previously published was also carried out. The resulting phylogenetic tree inferred from ITS1-5.8S-ITS2 region sequences obtained in this paper, together with those from other 11 taxa of rhinonyssid, shows slight differences from the current taxonomy of the Rhinonyssidae. This study appeals for the revision of the taxonomic status of the R. coniventris complex, as well as for the species included within it.

Abundância sazonal de aves migratórias na Área de Proteção Ambiental de Piaçabuçu, Alagoas, Brasil

Every year, thousands of limicola and migratory birds winter on the South American coast, between September and April, where they acquire body mass and undergo moulting before returning to their reproduction sites. Qualitative and quantitative studies were performed in the Piacabucu Protection Area located in the state of Alagoas, Brazil, by direct counting, aiming to follow upon the birds’ seasonal migration. Five species of Charadriidae family were recorded: Vanellus chilensis (Wagler, 1827); Pluvialis squatarola (Linnaeus, 1758); Charadrius semipalmatus Bonaparte, 1825; Charadrius collaris Vieillot, 1818 and Charadrius wilsonia (Ord, 1814), and five of the Scolopacidae family: Arenaria interpres (Linnaeus, 1758); Actitis macularius (Linnaeus, 1766); Catoptrophorus semipalmatus (Gmelin, 1789); Calidris pusilla (Linnaeus, 1766) and Calidris alba (Pallas, 1764). Pluvialis squatarola, Charadrius semipalmatus, Charadrius collaris, Arenaria interpres, Calidris pusilla and Calidris alba were considered constant (present in over 50% of observation time). Charadrius semipalmatus and Calidris alba showed highest level of frequency during November and December and March and September, respectively. Spearman correlation shows a strong dependency on migration of this species. The birds’ loyalty to the Piacabucu area seen in this research show that this is a preferred site for wintering thus reinforcing its importance for the conservation of the migratory species that utilize the site.

Short communication. Can highly pathogenic avian influenza (HPAI) reach the Iberian Peninsula from Asia by means of migratory birds?

This work discusses the possibilities of direct and indirect contact across Central Asia, between migratory bird populations from the Iberian Peninsula, Southwestern Eurasian and Eastern Asian countries. This fact should be considered when preparing surveillance studies for highly pathogenic avian influenza viruses. Records were checked from birds ringed or recovered between 1980 and 2002 in the Iberian Peninsula, an important wintering area for waterfowl in the European Union. This study only addresses migrations covering more than 5000 km and exclusively to or from Asia. A total of seven species have developed migratory routes between Europe and the Caspian Sea/Central Asia in the following proportions to the total of birds recovered: Podiceps nigricollis (17%), Anas penelope (11.1%), A. clypeata (2.17%), A. platyrhynchos (1.86%), Pluvialis squatarola (33.33%), Calidris ferruginea (1.36%) and Sterna sandvicensis (0.67%). These recovery rates suggest the possibility of interchange - at the Central Asia and Caspian breeding groundsbetween the populations originating in Europe and those from Southeast Asia. Over the following seasons, through direct migration, misorientation or, as frequently observed in certain duck species, through a phenomenon of abmigration, some birds with a priori Asian wintering quarters could conceivably escort their "European" brethren to this continent and thus contribute to the propagation of avian flu to so far virus-free areas.

Primary moult, body mass and migration of Grey Plovers Pluvialis squatarola in Britain

Long‐distance migrants have evolved complex strategies for the timing of their annual moult, fattening and migration cycles. These strategies are likely to vary at different stages of a bird's life. Ringing data on 6079 Grey Plovers Pluvialis squatarola, caught on the Wash, England, between 1959 and 1996, were analysed to relate migratory strategies to patterns of primary moult and body mass changes. Adults returning from breeding grounds had a shorter and delayed primary moult (duration 90 days, starting date 19 August) in comparison with over‐summering birds (duration 109 days, starting date 5 June). Three categories of migrant adults were identified on the basis of primary moult and body mass: (1) birds which did not moult, but increased body mass and migrated further south; (2) birds which moulted 1–3 inner primaries, suspended moult, increased body mass and migrated; and (3) birds which completed or suspended moult and wintered locally. In birds of the second category, timing of primary moult and body mass increase overlapped. Among wintering birds, 38% were in suspended moult. Ninety‐six per cent of birds that suspended moult at the beginning of winter were males and almost all completed moult in spring. Grey Plovers which left Britain in autumn had an average body mass of 280 g, enough to reach southern Morocco without refuelling. Both wintering adults and first‐year birds showed a prewinter body mass increase, peaking in December. Adults had a synchronized premigratory body mass increase in May, which suggested a negligible presence of African migrants. The average departure mass for spring migration, estimated at 316 g, would allow birds to fly non‐stop to the Siberian breeding grounds in western Taymyr.

Comparative use of longline oysterbeds and adjacent tidal flats by waterbirds

Commercial oyster Crassostrea spp. cultivation in intertidal habitats may degrade foraging habitat of waterbirds. Consequently, we compared species abundances, community similarity and diversity of waterbirds using longline oyster culture beds and adjacent control plots on tidal flats of Humboldt Bay, California. Abundances of most species differed significantly between treatments, with seven of 13 shorebirds Charadriiformes and three of four wading birds Ciconiiformes more abundant on longline plots. By contrast, Black-bellied Plover Pluvialis squatarola were more abundant on control plots. Marbled Godwit Limosa fedoa, Long-billed Curlew Numenius americanus and Dunlin Calidris alpina showed mixed results depending on location and Great Blue Heron Ardea herodias were more abundant only on one control plot. Community composition was similar on longline and control plots, although diversity (H′) was greater on longline plots. Varying species' responses to longline techniques may have been associated with interspecific differences in diet and foraging behaviour, and the impacts of longlines and oyster-harvesting on prey distribution. Overall, longlines did not negatively affect the foraging behaviour of most species, but the underlying causes for increased bird use may lead to impacts on other trophic levels and over a longer temporal scale.