71-467: The sanderling ( Calidris alba ) is a small wading bird. The name derives from Old English sand-yrðling , "sand-ploughman". The genus name is from Ancient Greek kalidris or skalidris , a term used by Aristotle for some grey-coloured waterside birds. The specific, alba , is Latin for "white". It is a circumpolar Arctic breeder, and is a long-distance migrant , wintering south to South America , South Europe , Africa , and Australia . It
142-465: A paraphyletic assemblage. However, it indicated that the plains wanderer actually belonged into one of them. Following recent studies (Ericson et al., 2003; Paton et al., 2003; Thomas et al., 2004a, b; van Tuinen et al., 2004; Paton & Baker, 2006), the waders may be more accurately subdivided as follows, with Charadrii being repurposed into a monophyletic suborder of plovers, oystercatchers, and their close relatives. The waders are traditionally
213-782: A beach are typically made from rock , such as sand , gravel , shingle , pebbles , etc., or biological sources, such as mollusc shells or coralline algae . Sediments settle in different densities and structures, depending on the local wave action and weather , creating different textures, colors and gradients or layers of material. Though some beaches form on inland freshwater locations such as lakes and rivers , most beaches are in coastal areas where wave or current action deposits and reworks sediments. Erosion and changing of beach geologies happens through natural processes, like wave action and extreme weather events . Where wind conditions are correct, beaches can be backed by coastal dunes which offer protection and regeneration for
284-423: A beach depends on whether the waves are constructive or destructive, and whether the material is sand or shingle. Waves are constructive if the period between their wave crests is long enough for the breaking water to recede and the sediment to settle before the succeeding wave arrives and breaks. Fine sediment transported from lower down the beach profile will compact if the receding water percolates or soaks into
355-409: A beach tends to indicate the energy of the waves and wind in the locality. Constructive waves move material up the beach while destructive waves move the material down the beach. During seasons when destructive waves are prevalent, the shallows will carry an increased load of sediment and organic matter in suspension. On sandy beaches, the turbulent backwash of destructive waves removes material forming
426-463: A filter for runoff from the coastal plain. If the runoff is naturally dispersed along the beach, water borne silt and organic matter will be retained on the land and will feed the flora in the coastal area. Runoff that is dispersed along the beach will tend to percolate through the beach and may emerge from the beach at low tide. The retention of the freshwater may also help to maintain underground water reserves and will resist salt water incursion. If
497-401: A gently sloping beach. On pebble and shingle beaches the swash is dissipated more quickly because the large particle size allows greater percolation , thereby reducing the power of the backwash, and the beach remains steep. Compacted fine sediments will form a smooth beach surface that resists wind and water erosion. During hot calm seasons, a crust may form on the surface of ocean beaches as
568-562: A greatly enlarged order Ciconiiformes . However, the classification of the Charadriiformes is one of the weakest points of the Sibley-Ahlquist taxonomy, as DNA–DNA hybridization has turned out to be incapable of properly resolving the interrelationships of the group. Formerly, the waders were united in a single suborder Charadrii , but this has turned out to be a " wastebasket taxon ", uniting no fewer than four charadriiform lineages in
639-530: A group of two Charadriiform suborders which include 13 families . Species in the third Charadriiform suborder, Lari , are not universally considered as waders, though the Larine families which may variously be included are listed below as well. Shorebirds is a blanket term used to refer to multiple bird species that live in wet, coastal environments. Because most these species spend much of their time near bodies of water, many have long legs suitable for wading (hence
710-715: A hind toe. Its behavior is also distinctive. The sanderling breeds in the High Arctic areas of North America , Europe and Asia . In North America, it breeds in the Canadian Arctic Archipelago , Nunavut , Greenland (and to a lesser extent Alaska ). In Eurasia , it breeds in Spitsbergen and areas of northern Russia from the Taymyr Peninsula to the New Siberian Islands . In the northern winter, it has
781-492: A lesser root ball. Erosion of beaches can expose less resilient soils and rocks to wind and wave action leading to undermining of coastal headlands eventually resulting in catastrophic collapse of large quantities of overburden into the shallows. This material may be distributed along the beach front leading to a change in the habitat as sea grasses and corals in the shallows may be buried or deprived of light and nutrients. Coastal areas settled by man inevitably become subject to
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#1732869606516852-546: A nearly cosmopolitan distribution across the world's marine coasts. It is a complete migrant , travelling between 3,000 to 10,000 km (1,900 to 6,200 mi) from its breeding grounds to its wintering sites. Birds that travel further also arrive later and leave sooner. Most adults leave the breeding grounds in July and early August, whereas juvenile birds leave in late August and early September. The northward migration begins in March at
923-465: A necessary and permanent feature of beach maintenance. During beach nourishment activities, care must be taken to place new sediments so that the new sediments compact and stabilize before aggressive wave or wind action can erode them. Material that is concentrated too far down the beach may form a temporary groyne that will encourage scouring behind it. Sediments that are too fine or too light may be eroded before they have compacted or been integrated into
994-462: A rapid cycle of growth throughout the 1850s and 1860s. The growth was intensified by the practice among the Lancashire cotton mill owners of closing the factories for a week every year to service and repair machinery. These became known as wakes weeks . Each town's mills would close for a different week, allowing Blackpool to manage a steady and reliable stream of visitors over a prolonged period in
1065-403: A result, an increase in dimorphism. Bigger males tend to have greater access (and appeal) to female mates because their larger size aids them in defeating other competitors. Likewise, if the species exhibits gender role reversal (where males take on roles traditionally done by females such as childcare and feeding), then males will select female mates based on traits that are the most appealing. In
1136-435: A shoreline subject to constant erosion and loss of foreshore. This is often required where the flow of new sediment caused by the longshore current has been disrupted by construction of harbors, breakwaters, causeways or boat ramps, creating new current flows that scour the sand from behind these structures and deprive the beach of restorative sediments. If the causes of the erosion are not addressed, beach nourishment can become
1207-443: A single female partner, males typically do not have distinctive dimorphic characteristics such as colored feathers, but they still tend to be larger in size compared to females. The suborder Charadrii displays the widest range of sexual dimorphisms seen in the order Charadriiformes. However, cases of sexual monomorphism, where there are no distinguishing physical features besides external genitalia, are also seen in this order. One of
1278-422: A tidal surge or tsunami which causes significant coastal flooding , substantial quantities of material may be eroded from the coastal plain or dunes behind the berm by receding water. This flow may alter the shape of the coastline, enlarge the mouths of rivers and create new deltas at the mouths of streams that had not been powerful enough to overcome longshore movement of sediment. The line between beach and dune
1349-438: Is a significant source of sand particles. Some species of fish that feed on algae attached to coral outcrops and rocks can create substantial quantities of sand particles over their lifetime as they nibble during feeding, digesting the organic matter , and discarding the rock and coral particles which pass through their digestive tracts. The composition of the beach depends upon the nature and quantity of sediments upstream of
1420-452: Is difficult to define in the field. Over any significant period of time, sediment is always being exchanged between them. The drift line (the high point of material deposited by waves) is one potential demarcation. This would be the point at which significant wind movement of sand could occur, since the normal waves do not wet the sand beyond this area. However, the drift line is likely to move inland under assault by storm waves. Beaches are
1491-416: Is highly gregarious in winter, sometimes forming large flocks on coastal mudflats or sandy beaches. It is somewhat unlike other sandpipers in appearance, which has led to the suggestion that it should be placed into a monotypic genus Crocethia . A more recent review (Thomas et al. , 2004) indicates, however, that the sanderling is a fairly typical " stint " or small sandpiper and should be separated from
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#17328696065161562-571: Is the least sandpiper , small adults of which can weigh as little as 15.5 grams (0.55 oz) and measure just over 13 centimetres (5 inches). The largest species is believed to be the Far Eastern curlew , at about 63 cm (25 in) and 860 grams (1 pound 14 ounces), although the beach thick-knee is the heaviest at about 1 kg (2 lb 3 oz). In the Sibley-Ahlquist taxonomy , waders and many other groups are subsumed into
1633-455: Is the importing and deposition of sand or other sediments in an effort to restore a beach that has been damaged by erosion. Beach nourishment often involves excavation of sediments from riverbeds or sand quarries. This excavated sediment may be substantially different in size and appearance to the naturally occurring beach sand. In extreme cases, beach nourishment may involve placement of large pebbles or rocks in an effort to permanently restore
1704-561: The Agreement on the Conservation of African-Eurasian Migratory Waterbirds ( AEWA ) applies. The sanderling is a small plump sandpiper, 18–20 cm (7.1–7.9 in) in length. Its weight ranges from 40–100 g (1.4–3.5 oz). The winter bird is very pale, almost white apart from a dark shoulder patch. This is the source of the specific name, alba , which is the Latin for "white". Later in
1775-508: The Delaware Bay area. In spring, the birds arrive on the High Arctic breeding grounds (see map), where they lay 3–4 eggs in a ground scrape. On the nesting grounds, these birds mainly eat insects and some plant material. The sanderling was described by the German naturalist Peter Simon Pallas in 1764 and given the binomial name Trynga alba . The sanderling is one of the species to which
1846-462: The Jacana species, females compete with each other for access to male mates, so females are larger in size. Males choose female mates based on who presents herself as the strongest and who 'owns' the most territory. Another factor that leads to the development of dimorphisms in species is natural selection . Natural selection focuses on traits and the environment's response to the traits in question; if
1917-452: The seashore is most commonly associated with the word beach , beaches are also found by lakes and alongside large rivers. Beach may refer to: The former are described in detail below; the larger geological units are discussed elsewhere under bars . There are several conspicuous parts to a beach that relate to the processes that form and shape it. The part mostly above water (depending upon tide), and more or less actively influenced by
1988-482: The 1720s; it had been a fashionable spa town since a stream of acidic water was discovered running from one of the cliffs to the south of the town in the 17th century. The first rolling bathing machines were introduced by 1735. The opening of the resort in Brighton and its reception of royal patronage from King George IV , extended the seaside as a resort for health and pleasure to the much larger London market, and
2059-481: The Arctic species, such as the little stint , are amongst the longest distance migrants, spending the non- breeding season in the southern hemisphere . Many of the smaller species found in coastal habitats, particularly but not exclusively the calidrids , are often named as "sandpipers", but this term does not have a strict meaning, since the upland sandpiper is a grassland species. The smallest member of this group
2130-435: The beach and into the sea. If the flow is constant, runoff from cleared land arriving at the beach head will tend to deposit this material into the sand changing its color, odor and fauna. The concentration of pedestrian and vehicular traffic accessing the beach for recreational purposes may cause increased erosion at the access points if measures are not taken to stabilize the beach surface above high-water mark. Recognition of
2201-452: The beach as a popular leisure resort from the mid-19th century was the first manifestation of what is now the global tourist industry. The first seaside resorts were opened in the 18th century for the aristocracy, who began to frequent the seaside as well as the then fashionable spa towns, for recreation and health. One of the earliest such seaside resorts, was Scarborough in Yorkshire during
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2272-612: The beach became a centre for upper-class pleasure and frivolity. This trend was praised and artistically elevated by the new romantic ideal of the picturesque landscape; Jane Austen 's unfinished novel Sanditon is an example of that. Later, Queen Victoria 's long-standing patronage of the Isle of Wight and Ramsgate in Kent ensured that a seaside residence was considered as a highly fashionable possession for those wealthy enough to afford more than one home. The extension of this form of leisure to
2343-401: The beach head, they may erode the beach creating a lagoon or delta. Dense vegetation tends to absorb rainfall reducing the speed of runoff and releasing it over longer periods of time. Destruction by burning or clearance of the natural vegetation tends to increase the speed and erosive power of runoff from rainfall. This runoff will tend to carry more silt and organic matter from the land onto
2414-523: The beach profile is higher in summer. The gentle wave action during this season tends to transport sediment up the beach towards the berm where it is deposited and remains while the water recedes. Onshore winds carry it further inland forming and enhancing dunes. Conversely, the beach profile is lower in the storm season (winter in temperate areas) due to the increased wave energy, and the shorter periods between breaking wave crests. Higher energy waves breaking in quick succession tend to mobilise sediment from
2485-404: The beach, and the speed of flow and turbidity of water and wind. Sediments are moved by moving water and wind according to their particle size and state of compaction. Particles tend to settle and compact in still water. Once compacted, they are more resistant to erosion . Established vegetation (especially species with complex network root systems) will resist erosion by slowing the fluid flow at
2556-1686: The beach. However, these natural forces have become more extreme due to climate change , permanently altering beaches at very rapid rates. Some estimates describe as much as 50 percent of the earth's sandy beaches disappearing by 2100 due to climate-change driven sea level rise. Sandy beaches occupy about one third of global coastlines. These beaches are popular for recreation , playing important economic and cultural roles—often driving local tourism industries. To support these uses, some beaches have human-made infrastructure, such as lifeguard posts, changing rooms , showers, shacks and bars. They may also have hospitality venues (such as resorts, camps, hotels, and restaurants) nearby or housing, both for permanent and seasonal residents. Human forces have significantly changed beaches globally: direct impacts include bad construction practices on dunes and coastlines, while indirect human impacts include water pollution , plastic pollution and coastal erosion from sea level rise and climate change . Some coastal management practices are designed to preserve or restore natural beach processes, while some beaches are actively restored through practices like beach nourishment . Wild beaches, also known as undeveloped or undiscovered beaches, are not developed for tourism or recreation. Preserved beaches are important biomes with important roles in aquatic or marine biodiversity, such as for breeding grounds for sea turtles or nesting areas for seabirds or penguins . Preserved beaches and their associated dune are important for protection from extreme weather for inland ecosystems and human infrastructure. Although
2627-413: The beach. Compacted sediment is more resistant to movement by turbulent water from succeeding waves. Conversely, waves are destructive if the period between the wave crests is short. Sediment that remains in suspension when the following wave crest arrives will not be able to settle and compact and will be more susceptible to erosion by longshore currents and receding tides. The nature of sediments found on
2698-489: The biggest factors that leads to the development of sexual dimorphism in shorebirds is sexual selection . Males with ideal characteristics favored by females are more likely to reproduce and pass on their genetic information to their offspring better than the males who lack such characteristics. Mentioned earlier, male shorebirds are typically larger in size compared to their female counterparts. Competition between males tends to lead to sexual selection toward larger males and as
2769-452: The character of underwater flora and fauna in the coastal shallows. Burning or clearance of vegetation on the land adjacent to the beach head, for farming and residential development, changes the surface wind patterns, and exposes the surface of the beach to wind erosion. Farming and residential development are also commonly associated with changes in local surface water flows. If these flows are concentrated in stormwater drains emptying onto
2840-444: The dangers of loss of beach front flora has caused many local authorities responsible for managing coastal areas to restrict beach access points by physical structures or legal sanctions, and fence off foredunes in an effort to protect the flora. These measures are often associated with the construction of structures at these access points to allow traffic to pass over or through the dunes without causing further damage. Beaches provide
2911-504: The effects of human-made structures and processes. Over long periods of time, these influences may substantially alter the shape of the coastline, and the character of the beach. Beachfront flora plays a major role in stabilizing the foredunes and preventing beach head erosion and inland movement of dunes. If flora with network root systems (creepers, grasses, and palms) are able to become established, they provide an effective coastal defense as they trap sand particles and rainwater and enrich
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2982-434: The established vegetation. Foreign unwashed sediments may introduce flora or fauna that are not usually found in that locality. Brighton Beach, on the south coast of England, is a shingle beach that has been nourished with very large pebbles in an effort to withstand the erosion of the upper area of the beach. These large pebbles made the beach unwelcoming for pedestrians for a period of time until natural processes integrated
3053-417: The feature. Where wind is the force distributing the grains inland, the deposit behind the beach becomes a dune . These geomorphic features compose what is called the beach profile . The beach profile changes seasonally due to the change in wave energy experienced during summer and winter months. In temperate areas where summer is characterised by calmer seas and longer periods between breaking wave crests,
3124-450: The heat of the sun evaporates the water leaving the salt which crystallises around the sand particles. This crust forms an additional protective layer that resists wind erosion unless disturbed by animals or dissolved by the advancing tide. Cusps and horns form where incoming waves divide, depositing sand as horns and scouring out sand to form cusps. This forms the uneven face on some sand shorelines . White sand beaches look white because
3195-449: The height of the water table. Some flora naturally occurring on the beach head requires freshwater runoff from the land. Diversion of freshwater runoff into drains may deprive these plants of their water supplies and allow sea water incursion, increasing the saltiness of the groundwater. Species that are not able to survive in salt water may die and be replaced by mangroves or other species adapted to salty environments. Beach nourishment
3266-485: The large knots with its closest relatives in a distinct genus. This bird is similar in size to a dunlin , but stouter, with a thick bill. It shows a strong white wingbar in flight, and runs along the sandy beaches it prefers with a characteristic "bicycling" action of its legs, stopping frequently to pick small food items. It eats small crabs and other small invertebrates . In spring, birds migrating north from South America consume large numbers of horseshoe crab eggs in
3337-445: The middle and working classes began with the development of the railways in the 1840s, which offered cheap fares to fast-growing resort towns. In particular, the completion of a branch line to the small seaside town of Blackpool from Poulton led to a sustained economic and demographic boom. A sudden influx of visitors, arriving by rail, led entrepreneurs to build accommodation and create new attractions, leading to more visitors and
3408-640: The mud and sand, usually small arthropods such as aquatic insects or crustaceans . The term "wader" is used in Europe, while "shorebird" is used in North America, where "wader" may be used instead to refer to long-legged wading birds such as storks and herons . There are about 210 species of wader, most of which live in wetland or coastal environments. Many species of Arctic and temperate regions are strongly migratory , but tropical birds are often resident, or move only in response to rainfall patterns. Some of
3479-477: The name 'Waders'). Some species prefer locations with rocks or mud. Many shorebirds display migratory patterns and often migrate before breeding season. These behaviors explain the long wing lengths observed in species, and can also account for the efficient metabolisms that give the birds energy during long migrations . The majority of species eat small invertebrates picked out of mud or exposed soil. Different lengths of bills enable different species to feed in
3550-612: The naturally occurring shingle into the pebble base. Even in Roman times, wealthy people spent their free time on the coast. They also built large villa complexes with bathing facilities (so-called maritime villas) in particularly beautiful locations. Excavations of Roman architecture can still be found today, for example on the Amalfi Coast near Naples and in Barcola in Trieste. The development of
3621-621: The permanent water forming offshore bars, lagoons or increasing the area of the beach exposed at low tide. Large and rapid movements of exposed sand can bury and smother flora in adjacent areas, aggravating the loss of habitat for fauna, and enlarging the area of instability. If there is an adequate supply of sand, and weather conditions do not allow vegetation to recover and stabilize the sediment, wind-blown sand can continue to advance, engulfing and permanently altering downwind landscapes. Sediment moved by waves or receding floodwaters can be deposited in coastal shallows, engulfing reed beds and changing
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#17328696065163692-564: The quartz or eroded limestone in the sand reflects or scatters sunlight without absorbing other colors. The composition of the sand varies depending on the local minerals and geology. Some of the types of sand found in beaches around the world are: Beaches are changed in shape chiefly by the movement of water and wind. Any weather event that is associated with turbid or fast-flowing water or high winds will erode exposed beaches. Longshore currents will tend to replenish beach sediments and repair storm damage. Tidal waterways generally change
3763-415: The result of wave action by which waves or currents move sand or other loose sediments of which the beach is made as these particles are held in suspension . Alternatively, sand may be moved by saltation (a bouncing movement of large particles). Beach materials come from erosion of rocks offshore, as well as from headland erosion and slumping producing deposits of scree . A coral reef offshore
3834-435: The said trait increases the overall fitness of the individual possessing it, then it will be 'selected' and eventually become a permanent part of the population's gene pool. For example, depending on the food available in a shorebird specie's respective niche , bigger bill sizes may be favored in all individuals. This would essentially lead to monomorphism within the species but is subject to change once sexual selection acts on
3905-818: The same habitat, particularly on the coast, without direct competition for food. Many waders have sensitive nerve endings at the end of their bills which enable them to detect prey items hidden in mud or soft soil. Some larger species, particularly those adapted to drier habitats will take larger prey including insects and small reptiles . Shorebirds, like many other animals, exhibit phenotypic differences between males and females, also known as sexual dimorphism . In shorebirds, various sexual dimorphisms are seen, including, but not limited to, size (e.g. body size, bill size), color, and agility. In polygynous species, where one male individual mates with multiple female partners over his lifetime, dimorphisms tend to be more diverse. In monogamous species, where male individuals mate with
3976-412: The shallows, keeping it in suspension where it is prone to be carried along the beach by longshore currents, or carried out to sea to form longshore bars, especially if the longshore current meets an outflow from a river or flooding stream. The removal of sediment from the beach berm and dune thus decreases the beach profile. If storms coincide with unusually high tides, or with a freak wave event such as
4047-487: The shape of their adjacent beaches by small degrees with every tidal cycle. Over time these changes can become substantial leading to significant changes in the size and location of the beach. Changes in the shape of the beach may undermine the roots of large trees and other flora. Many beach adapted species (such as coconut palms) have a fine root system and large root ball which tends to withstand wave and wind action and tends to stabilize beaches better than other trees with
4118-562: The shape, profile and location of a beach within hours. Destruction of flora on the berm by the use of herbicides, excessive pedestrian or vehicle traffic, or disruption to freshwater flows may lead to erosion of the berm and dunes. While the destruction of flora may be a gradual process that is imperceptible to regular beach users, it often becomes immediately apparent after storms associated with high winds and freak wave events that can rapidly move large volumes of exposed and unstable sand, depositing them further inland, or carrying them out into
4189-449: The shores of lakes and rivers. More infrequently, it may occur on rocky shores. The sanderling consists of two subspecies: Sanderlings feed on invertebrate prey buried in the sand in the upper intertidal zone . In North America, this diet largely consists of the isopods Excirolana linguifrons , Excirolana kincaidii , and the mole crab, Emerita analoga . When the tide is out, these crustaceans live in burrows some way beneath
4260-455: The southern end of their winter distribution. The breeding habitat of the sanderling is coastal tundra north of 5 °C (41 °F) July isotherm . The species typically chooses nesting sites on dry stony areas near wet areas, from 60 m (200 ft) above sea level to 800 m (2,600 ft). During the winter and its migration, it is most commonly found on coastal sandy beaches , but also occurs on tidal sand flats, mud flats and
4331-408: The summer, the face and throat become brick-red. The juvenile bird is spangled black and white, and shows much more contrast than the adult. If its size is misjudged, a sanderling in breeding plumage can be mistaken for some varieties of stint , or a sanderling in winter plumage can be mistaken for a dunlin or red knot . It can be told from other small wading birds, given good views, by its lack of
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#17328696065164402-566: The summer. A prominent feature of the resort was the promenade and the pleasure piers , where an eclectic variety of performances vied for the people's attention. In 1863, the North Pier in Blackpool was completed, rapidly becoming a centre of attraction for upper class visitors. Central Pier was completed in 1868, with a theatre and a large open-air dance floor. Many of the popular beach resorts were equipped with bathing machines , because even
4473-425: The surface flow of the runoff is diverted and concentrated by drains that create constant flows over the beach above the sea or river level, the beach will be eroded and ultimately form an inlet unless longshore flows deposit sediments to repair the breach. Once eroded, an inlet may allow tidal inflows of salt water to pollute areas inland from the beach and may also affect the quality of underground water supplies and
4544-519: The surface layer of the dunes, allowing other plant species to become established. They also protect the berm from erosion by high winds, freak waves and subsiding floodwaters. Over long periods of time, well-stabilized foreshore areas will tend to accrete, while unstabilized foreshores will tend to erode, leading to substantial changes in the shape of the coastline. These changes usually occur over periods of many years. Freak wave events such as tsunami, tidal waves, and storm surges may substantially alter
4615-657: The surface layer. When affected by moving water or wind, particles that are eroded and held in suspension will increase the erosive power of the fluid that holds them by increasing the average density, viscosity, and volume of the moving fluid. Coastlines facing very energetic wind and wave systems will tend to hold only large rocks as smaller particles will be held in suspension in the turbid water column and carried to calmer areas by longshore currents and tides. Coastlines that are protected from waves and winds will tend to allow finer sediments such as clay and mud to precipitate creating mud flats and mangrove forests. The shape of
4686-406: The surface. At breeding time sanderlings are territorial , with the male aggressively defending its territory. They may either form monogamous pairs or polyandrous (one female and two male) pairings. Wader Waders or shorebirds are birds of the order Charadriiformes commonly found wading along shorelines and mudflats in order to forage for food crawling or burrowing in
4757-439: The surface. When the tide comes in, they move into the upper layers of sand and feed on the plankton and detritus that washes over them with each wave. They then burrow rapidly down again as the water retreats. They leave no marks on the surface, so the sanderlings hunt for them by plunging their beaks into the sand at random, consuming whatever they find. Their bills can penetrate only 2 or 3 cm (0.79 or 1.18 in) and as
4828-399: The trait. Sexual selection could give rise to males with relatively larger bills than females if males used their bills to compete with other males. If larger bill size assisted the male in gathering resources, it would also make him more attractive to female mates. Beach A beach is a landform alongside a body of water which consists of loose particles. The particles composing
4899-528: The water swirls around and retreats, the sand is softer; this makes it easier for the birds' beaks to penetrate further. In the spring, when much breeding activity is taking place in the benthic community, there may be as many as 4000 invertebrates per square metre, but their average size is smaller than later in the year. The birds appear to rush madly around at the edge of the surf, but in reality they are maximising their chances of catching as many prey animals as possible when they are at their most vulnerable near
4970-408: The waves at some point in the tide, is termed the beach berm. The berm is the deposit of material comprising the active shoreline. The berm has a crest (top) and a face —the latter being the slope leading down towards the water from the crest. At the very bottom of the face, there may be a trough , and further seaward one or more long shore bars: slightly raised, underwater embankments formed where
5041-434: The waves first start to break. The sand deposit may extend well inland from the berm crest , where there may be evidence of one or more older crests (the storm beach ) resulting from very large storm waves and beyond the influence of the normal waves. At some point the influence of the waves (even storm waves) on the material comprising the beach stops, and if the particles are small enough (sand size or smaller), winds shape
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