Cliff Ledges Research Articles

Status and Population Trends of Great Cormorant Phalacrocorax carbo sinensis Breeding in Greece

We analysed trends in the breeding population of Great Cormorants in Greece during the period 1988–2014 when at least 20 colonies were recorded. The number of colonies doubled over the study period reaching 14 in 2014 from seven in 1988. There was also a continuous increase in the number of nests: from 952 in 1988 to 9256 in 2014, presenting an annual change of +26.5% ± 0.05 (SD). Most of the colonies were situated in freshwater lakes, three in deltas and one on the seacoast. Nine colonies were mixed with other colonially nesting species (mostly from the Ardeidae family). Of the 14 colonies 11 were found in trees. Two colonies were situated on the ground, four in bushes, two on reed rhizome islets and one on cliff ledges. Five out of the 14 active colonies in 2014, comprising 87% of the total recorded nests, were in wetlands of low altitude (0–45 m a.s.l.). The rest were situated in mountainous wetlands at altitudes ranging from 235 to 853 m a.s.l. One colony, at Lake Kerkini, contained the majority of nests in Greece (6650, being 72% in 2014). The second largest colony, at Lake Volvi, had 900 nests, followed by the Greek part of Prespa with 625 nests (in three colonies) in 2014. The percentage of nests in newly established colonies increased after 2003, reaching its highest value (14%) in 2009. The reason for the growth in both colonies and nests over the years is attributed to the increasing availability of fish, the protection status of wetlands and the absence of disturbance. Particularly after 2002 the species increased in numbers and established colonies in new areas, which is probably related to the expanding breeding populations of the species in north-eastern European countries and a corresponding increase in wintering numbers in Greece. This needs further attention by monitoring and research.

Mentzelia oligosperma Nutt. (Stickleaf, Loasaceae): Distribution and Abundance in Illinois

We conducted field searches for populations of Mentzelia oligosperma Nutt. (stickleaf) throughout the known range of this species in Illinois during the growing seasons of 2010–2019. A species common to the prairies and plains of western North America, it is habitat-specific and rarely observed in Illinois. Populations are confined mostly to narrow limestone cliff ledges along the bluffs of the Mississippi River in Adams, Calhoun, Monroe, Pike, and Randolph counties on the western border of the state. We identified 18 potential stickleaf sites based upon herbaria searches and interviews with biologists. Subsequent field investigations determined the presence of 15 extant sites, including two new locations at Hull in Pike County and the Fults Hill Prairie Annex in Monroe County. Five historic populations are extirpated. The state total of 498 plants represents populations ranging from six to 85 individuals at 15 sites, with most locations having fewer than 20 individuals. Stickleaf is currently listed as endangered by the Illinois Endangered Species Protection Board due to its restricted habitat and low population densities.

Ecology of the Golden Eagle in Mongolia, Part 1: Breeding Distribution and Nest-Site Descriptions

During seven expeditions across Mongolia, we found 40 Golden Eagle (Aquila chrysaetos) breeding territories with eggs or young. At 20 other locations, we either found old eagle nests with Golden Eagle feathers or saw adult eagles but found no eggs or young. Golden Eagles nested in all but the driest portions of the Gobi Desert and the easternmost grasslands. Nearly all pairs had alternate nests. Of 53 nests used, 60% were on cliff ledges as is typical around the world. However, 19% were on the ground or at other sites that were easily accessible to canid predators, with the most vulnerable nests small and seldom or never reused. The most unusual nests included one atop a conical basalt peak, one on relatively flat ground among tall boulders, four on steep hillsides, one on almost flat ground amid rocky protrusions, and three on cliff tops. Where tall cliffs with many ledges were available, the eagles nested at least 7 m above the ground. Nest construction materials were often unusual and included trash, patches of large mammal hides, paper money, and clothing.

Multi-Channel Ground-Penetrating Radar Array Surveys of the Iron Age and Medieval Ringfort Bårby on the Island of Öland, Sweden

As a part of the project “The Big Five”, large-scale multi-channel ground-penetrating radar surveys were carried out at Bårby ringfort (Swedish: borg), Öland, Sweden. The surveys were carried out using a MALÅ Imaging Radar Array (MIRA) system and aimed at mapping possible buried Iron Age and Medieval remains through the interior in order to better understand the purpose of the fort during its periods of use. An additional goal was to evaluate the impact of earlier farming on the preservation of the archaeological remains. The data provided clear evidence of well-preserved Iron Age and Medieval buildings inside the fort. The size and the pattern of the Iron Age houses suggest close similarities with, for example, the previously excavated fort at Eketorp on Öland. Given the presence of a substantial cultural layer together with a large number of artefacts recovered during a metal detection survey, it is suggested that Bårby borg’s primary function during the Iron Age was as a fortified village. The Medieval houses partly cover some of the Iron Age buildings. They are placed in a U-shape with an open square in the middle facing the edge of a limestone cliff. As in the case of Eketorp, it is suggested that the activities during Medieval times changed, but the precise purpose of the Medieval Bårby settlement is still a question open for debate. Future targeted archaeological investigations are needed in order to better understand its purpose. Rescue excavations may also be necessary, as the western steep cliff ledge is eroding and the well-preserved archaeological remains are at risk of being destroyed.

Grazing exclusion and vegetation change in an upland grassland with patches of tall herbs

AbstractQuestionsThe hydrophilous tall herb community is an important refuge for grazing‐sensitive broad‐leaved flowering plants. It is distributed throughout upland Europe but overgrazing has contributed to an unfavourable conservation status. To guide tall herb restoration, we asked: (a) Does using grazing exclusion where the tall herb habitat is confined to cliff ledge patches promote an expansion into the grassland below? (b) Does this management negatively affect vascular plant diversity?LocationBen Lawers NNR, Scotland.MethodsLarge herbivores have been excluded from a 180‐ha area containing patches of outcrops rich in tall herb habitat. Using 1999 and 2017 surveys of permanent plot transects located in the grassland below (Before–After design), we quantify impacts on community composition and tall herb abundance.ResultsSpecies diversity remained constant although total species richness declined slightly and tall herb species richness increased significantly. There was a large expansion in tall herb cover (+29.67%) and a corresponding decrease in grass cover (−26.16%), as well as smaller increases in bryophytes and small herbs and a reduction in bare ground. Community composition shifted significantly from species typical of upland calcareous grassland towards those found in tall herb habitats. Seven tall herb species were amongst those showing the greatest increase in cover, along with taller grasses and understory herbs. Grazing tolerant grasses and low‐growing, prostrate and annual herbs decreased. Competition for light, rather than resilience to herbivory, now has a major influence on the vegetation.ConclusionsUsing grazing exclusion where the tall herb habitat is largely confined to patches on cliff ledges facilitates an expansion into the upland grassland below. Although this management favours species tolerant of shadier conditions, there is no evidence of a negative impact on vascular plant community composition. It is therefore an effective strategy for promoting the restoration and favourable condition of this grazing‐sensitive habitat.

Mucky guillemot eggs are definitely not self-cleaning

Common guillemots really do put all their eggs in one basket; or at least one egg. Jostled by their neighbours and perched high on rain-lashed cliff ledges, pairs of guillemot parents tend their precious individual egg directly on the rock. ‘Breeding at high density is the guillemots’ way of protecting their eggs and chicks from predators such as gulls and ravens, but it means that colonies become rather unhygienic’, says Duncan Jackson from the University of Sheffield, UK, describing how the eggs become smeared with the neighbours’ faeces, potentially smothering the developing embryos within. So when Timothy Birkhead, also from Sheffield, heard press reports that muck does not stick to self-cleaning guillemot eggs, he was sceptical. ‘After studying guillemots on Skomer Island, Wales, for 40 years I knew that their eggs were invariably covered in it’, says Birkhead.Determined to dispel the self-cleaning modern myth, Birkhead and Jamie Thompson obtained a licence giving them permission to abseil down to the bird's precarious cliff face breeding ledges to photograph the eggs and collect a few. Back in Sheffield, they carefully cleaned the fragile shells before cutting them into 1 cm2 portions and gluing a fragment across the top of a glass vial filled with carbon dioxide to measure how much gas diffuses through the shell. Next, they daubed filth that had been collected from the nesting site over the shell and re-measured the vial's carbon dioxide level. Sure enough, less gas was able to diffuse across the mucky shells.Wondering how many of the shell pores that allow gas into and out of the egg become clogged when covered in muck, Jackson retrieved the fragments and filmed them with X-rays to build a detailed view of the shell and its layer of dirt. After reconstructing both, it was apparent that the shells that had the most clogged pores tended to have the lowest gas permeability.But it was still unclear whether the shells were capable of repelling water to wash away dirt. To test the shell's self-cleaning powers, Jackson gently tilted portions of the egg and sprinkled vacuum cleaner dust over them before dripping on droplets of water to see if they rolled away and washed the dirt off. ‘If the eggshell's surface still contained debris suspended in water droplets after our simple trial then the shell could not be self-cleaning’, says Jackson. However, despite their impromptu drenching, each fragment remained awash with a puddle of dusty water. The eggs were not self-cleaning, in contrast to the famously self-cleaning cauliflower and broccoli leaves that Jackson tested, which were immaculate after the simulated rain.Having confirmed that the eggs are not self-cleaning, Birkhead and Nicola Hemmings suggested that Jackson test whether the waterproof outer layer of the shell – known as shell accessory material – may somehow prevent the essential pores from becoming blocked. Stripping the complex outer layer – including calcium carbonate, fats, sugars, proteins and pigment – from the surface of the egg, Jackson then daubed muck on the exposed shell and filmed the surface with X-rays. The stripped soiled egg was in much worse shape than the shell that retained its outer coating, with more than three times as many pores clogged with dirt. ‘It looks like shell accessory material limits the amount of debris that can enter and block pores, which means that gases can travel through the guillemot's eggshell even when the egg is dirty’, says Jackson, although it is not clear how the outer layer prevents blockages. But one thing is certain: press reports that guillemot eggs are self-cleaning were a little premature.

Going Vertical

ABSTRACTMost archaeological practice involves horizontal excavations of ancient occupations and cemeteries, but the Chachapoya of Peru's eastern montane built tombs along narrow cliff ledges, which require innovative methods of investigation. Many of these sites are becoming exposed and threatened due to increased deforestation. The La Petaca mortuary complex includes 125 constructed platforms, modified ledges, mausoleums, and caves containing human remains across one section of an exposed rock face approximately 200 m across by approximately 80 m high. While the site has been looted and damaged due to various taphonomic processes (including ecological, geological, and cultural), we argue that there are recoverable details, especially in relation to how the ancient Chachapoya people created and accessed these vertical spaces. Through collaboration with technical professionals, we identified and documented many tombs using vertical progression techniques. This valuable partnership between spelunkers and archaeologists allowed us to develop techniques for “vertical archaeology,” including safe access in order to be able to document, sample, and make detailed observations of building methods and burial contents.

Common guillemot (Uria aalge) eggs are not self-cleaning.

Birds are arguably the most evolutionarily successful extant vertebrate taxon, in part because of their ability to reproduce in virtually all terrestrial habitats. Common guillemots, Uria aalge, incubate their single egg in an unusual and harsh environment; on exposed cliff ledges, without a nest, and in close proximity to conspecifics. As a consequence, the surface of guillemot eggshells is frequently contaminated with faeces, dirt, water and other detritus, which may impede gas exchange or facilitate microbial infection of the developing embryo. Despite this, guillemot chicks survive incubation and hatch from eggs heavily covered with debris. To establish how guillemot eggs cope with external debris, we tested three hypotheses: (1) contamination by debris does not reduce gas exchange efficacy of the eggshell to a degree that may impede normal embryo development; (2) the guillemot eggshell surface is self-cleaning; (3) shell accessory material (SAM) prevents debris from blocking pores, allowing relatively unrestricted gas diffusion across the eggshell. We showed that natural debris reduces the conductance of gases across the guillemot eggshell by blocking gas exchange pores. Despite this problem, we found no evidence that guillemot eggshells are self-cleaning, but instead showed that the presence of SAM on the eggshell surface largely prevents pore blockages from occurring. Our results demonstrate that SAM is a crucial feature of the eggshell surface in a species with eggs that are frequently in contact with debris, acting to minimise pore blockages and thus ensure a sufficient rate of gas diffusion for embryo development.

The point of a Guillemot's egg

The adaptive significance of avian egg shape in birds is poorly understood. The pyriform (pear‐like) shape of the Common Guillemot's Uria aalge egg has long been considered to be an adaptation to prevent eggs rolling off the bare cliff ledges on which this species breeds. Rolling was thought to be prevented either by the egg spinning like a top, which is not the case, or by rolling in an arc, which it does but with little influence on whether the egg will fall from a ledge. We therefore sought alternative explanations for the pyriform shape of the Common Guillemot's egg. This species breeds in extremely dense colonies, which makes their eggs vulnerable to mechanical damage from conspecifics, and to contamination by debris such as faeces and soil. We present evidence consistent with both these possible explanations. First, the pyriform shape of Common Guillemot eggs means that a higher proportion of the eggshell lies in contact with the substrate and this may minimize the effect of impacts. Resistance to impacts may be further enhanced because their eggshells are especially thick where they are in contact with the substrate. Secondly, Common Guillemot eggs are often heavily contaminated with faecal material and other debris during incubation. Most contamination is on the pointed end of the egg where it is in contact with the substrate; the pyriform shape thus keeps the blunt end of the egg, which has the highest porosity, relatively free of contamination, which in turn may facilitate both gas exchange during incubation and the hatching process, because the chick emerges from the blunt end of the egg.

Egg shape in the Common Guillemot Uria aalge and Brunnich\u2019s Guillemot U. lomvia: not a rolling matter?

The adaptive significance of avian egg shape is poorly understood, and has been studied only in those species producing pyriform (pear-shaped, or pointed) eggs: waders and guillemots (murres) Uria spp., albeit to a limited extent. In the latter, it is widely believed that the pyriform shape has evolved to minimise their likelihood of rolling off a cliff ledge: the idea being that the more pointed the egg, the narrower the arc in which it rolls, and the less likely it is it will fall from a cliff ledge. Previous research also claimed that the rolling trajectory—the diameter of the arc they describe—of Common Guillemot U. aalge eggs is influenced not only by its shape but also by its mass, with heavier (i.e. larger) eggs describing a wider arc than lighter eggs. The finding that both shape and mass determined the rolling trajectory of Common Guillemot eggs (the shape–mass hypothesis) was used to explain the apparent anomaly that Brünnich’s Guillemot U. lomvia produce eggs that are less pointed, yet breed on narrower ledges than Common Guillemots. They are able to do this, it was suggested, because Brünnich’s Guillemot eggs are smaller and lighter in mass than those of Common Guillemots. However, since some populations of Brünnich’s Guillemots produce eggs that are as large or larger than those of some Common Guillemot populations, the shape–mass hypothesis predicts that that (1) larger (i.e. heavier) eggs of both guillemot species will be more pyriform (pointed) in shape, and (2) that eggs of the two species of same mass should be similarly pointed. We tested these predictions and found: (1) only a weak, positive association between egg volume and pointedness in both guillemot species (<3% of the variation in egg shape explained by egg volume), and (2) no evidence that eggs of the two species of similar mass were more similar in shape: regardless of their mass, Brunnich’s Guillemot eggs were less pointed than Common Guillemot eggs. Overall, our results call into question the long-held belief that protection from rolling is the main selective factor driving guillemot egg shape.

Examining the effects of ground motion and rock strength on the size of boulders falling from an overhanging cliff

The presence of boulders, a result of rockfall events, at the foot of cliffs testifies for a mass wasting process which is widely observed and is often considered to be triggered by earthquakes. Here we investigate boulders under an overhanging cliff with an emphasis on the principal factors that control boulder size. We used a conceptual cantilever beam model to predict the expected maximum length of the overhanging cliff. We then compared these calculated lengths to those of the field observed boulders and the length of the overhanging cliff ledge. Our observations show that the actual lengths of the boulders and overhanging cliff are much shorter than expected from the model. As the study area is located in a tectonically active region, we first suggested solving this discrepancy by adding the possible effect of ground motion on the size of a boulder. Detailed pseudo-static and dynamic analysis of the effect of earthquakes on the failure of rock beams shows that boulder length may not significantly be shortened by induced ground motions. We therefore conclude that strong earthquakes, although triggering rockfalls, are not expected to control the resultant size of the boulders found at the base of overhanging cliffs. We alternatively suggest that the maximum length of a boulder is strongly controlled by the rock strength. We conclude that the maximum boulder size that may fall during an earthquake event can be predicted by calculating the cantilever critical length including the effect of the rock size on its tensile strength. This, together with the measured rock discontinuities in an overhanging cliff suggests an upper-bound for the volume of the falling boulders, a crucial factor in assessing rockfall hazards.

Pigeons and choughs, a usual resource for the Neanderthals in Gibraltar

An ecological perspective is essential to our understanding of variations in the faunal communities and their relationships with human groups, as well as the foraging strategies that hominids practised in Pleistocene environments. Using the Middle Palaeolithic avifauna, the ecological quality of the Strait of Gibraltar shows a complex scenario in which cliff-dwelling species represented one of the most important and abundant taxa. Pigeons (Columba) are a species that favour rocky habitats, typically nesting on cliff ledges and at the entrances to large caves, while corvids are forest birds and only a few Palaearctic species, including colonial ones such as choughs (Pyrrhocorax), can also breed on rocky outcrops or cliffs. At Gorham's Cave, Gibraltar, the Neanderthals exploited pigeons and choughs for a period of more than 40 ka, with the earliest evidence dating from at least 67 ka. We show that such exploitation was not occasional, having found repeated evidence of the practice in different layers within the cave. The Gibraltar sites seem to provide ideal conditions for broadening the spectrum of prey during MIS 3. The high diversity of avian species identified in the faunal assemblages could be related to the location of the caves, which enables the exploitation of coastal and rocky habitats. This fact seems to point to the unique circumstances and foraging opportunities at this particular locality, where the available prey and environmental conditions seem to be influencing, among other factors such as site functionality and socio-cultural variables, the Neanderthal diet.

The earliest pigeon fanciers

Feral Pigeons have colonised all corners of the Earth, having developed a close association with humans and their activities. The wild ancestor of the Feral Pigeon, the Rock Dove, is a species of rocky habitats, nesting typically on cliff ledges and at the entrance to large caves. This habit would have brought them into close contact with cave-dwelling humans, a relationship usually linked to the development of dwellings in the Neolithic. We show that the association between humans and Rock Doves is an ancient one with its roots in the Palaeolithic and predates the arrival of modern humans into Europe. At Gorham's Cave, Gibraltar, the Neanderthals exploited Rock Doves for food for a period of over 40 thousand years, the earliest evidence dating to at least 67 thousand years ago. We show that the exploitation was not casual or sporadic, having found repeated evidence of the practice in different, widely spaced, temporal contexts within the cave. Our results point to hitherto unappreciated capacities of the Neanderthals to exploit birds as food resources on a regular basis. More so, they were practising it long before the arrival of modern humans and had therefore invented it independently.

Breeding-Site Selection By Ferruginous Hawks Within Utah's Uintah Basin

We examined factors that might influence breeding-site selection in Ferruginous Hawks (Buteo regalis) in the Uintah Basin, Utah, an area undergoing rapid oil and gas development. We located 31 occupied nests of Ferruginous Hawk (10 during 2002, 10 during 2003, and 11 during 2004) and compared them to 32 historical nest sites of Ferruginous Hawks that were unoccupied during our study, and 32 random sites. Ferruginous Hawks selected nesting areas that were dominated by mixed desert-shrub vegetation communities with scattered Utah juniper trees (Juniperus osteosperma), higher prey abundance, and a high number of active petroleum wells. Within occupied territories, Ferruginous Hawks selected nest sites in juniper trees, on cliff ledges, or on rock pinnacles that occurred in areas with higher prey abundance, close to an active well, and within 2–3.5 km of the nearest occupied nest of another raptor. The counterintuitive association between nesting activity and oil development may be the result of: (1) a spurious relationship between the occurrence of oil and gas reserves and suitable breeding habitat, (2) a time lag in the response of nesting pairs to development, or (3) oil and gas developments indirectly benefiting nesting pairs by improving the habitat of prey species and subsequently increasing prey densities, and/or reducing the threat of predation to Ferruginous Hawks or their young.

Peregrine Falcons and Golden Eagles Use Swallow Guano to Support Nests on the Same Cliff Ledge in Interior Alaska

Peregrine Falcons and Golden Eagles Use Swallow Guano to Support Nests on the Same Cliff Ledge in Interior Alaska

Status and Conservation of the Common MurreUria aalgeBreeding on Teuri Island, Hokkaido

The Common Murre Uria aalge is listed as an endangered species in Japan and breeds only on Teuri Island, Hokkaido. The Teuri Island population has decreased from 8,000 birds in 1963 to 19 in 2010. They bred on sea-stack and cliff ledges (open habitat) before 1994, but mostly in cliff caves (closed habitat) after 1994. In closed habitat, the fledging rate was greater and the rate of population decrease was smaller than in open habitat. Restoration actions (decoys and sounds) were effective in attracting murres, but did not enhance the fledging rate sufficiently to raise their population, possibly because of predation by avian predators (Slatybacked Gulls Larus schistisagus and Jungle Crows Corvus macrorhynchos). Using the fledging rate observed in closed habitat and other demographic parameters found in references, Population Viability Analysis shows that the probability of extinction of the Teuri population within 50 years is 66%. To improve the fledging rate and make the restoration actions more effective, we recommend the control of avian predators.

Gopher Snake Searching Cliff Swallow Nests in East Central Utah

We report details of a serendipitous encounter in July 2010 with a gopher snake (Pituophis catenifer) hunting in the mud nests of Cliff Swallows (Petrochelidon pyrrhonota). The swallow nests occurred beneath a deeply overhung sandstone cliff ledge in a box canyon of Ferron Creek in the shale deserts near Ferren, Emery County, Utah. The inaccessibility of the nests and the movement of the snake to and through them attest to both the extraordinary climbing ability of the gopher snake and the nest site selection and nest construction ability of the swallows.

Behaviour and survival of Common Guillemot Uria aalge chicks at departure from a nest site in the Baltic Sea

Common Guillemots Uria aalge often breed high up in cliffs, forcing the juveniles to jump down to the beach or sea when leaving their nests. We studied survival of Common Guillemot chicks at time of nest departure on the island Lilla Karlsö in the Baltic Sea. All jumps were conducted either together with one of the parents, or, more commonly, the parent flew down shortly before the chick jumped. At this point, the parent was always found waiting for the chick directly underneath the nest, either on the beach or in the water, and never farther out than five meters if there was no beach below the cliff. If separated, all observed parents and juveniles reunited within one minute and then swam close together out to sea. Juvenile mortality was very low, only 0.5% in 2011, with 2 of 426 chicks dying. In both cases hitting a lower cliff ledge caused the mortality. No case of predation was observed. The high survival rates are most likely due to the chicks’ close proximity to their male parent at all times.

Biological Flora of the British Isles: Pseudorchis albida (L.) Á. &amp; D. Löve

1. This account presents information on all aspects of the biology of Pseudorchis albida (Small White Orchid) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to abiotic and biotic factors, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, and conservation. 2. Pseudorchis albida is a native British herb growing in several plant communities of semi-natural habitats, typically in recently burned heather moorlands, upland well-drained pastures and meadows, and cliff ledges. Although the species is able to tolerate a wide range of ecological conditions from mildly acid to base-rich soils, it is limited mainly to open, short and nutrient-poor stands. Typical British plant communities include Calluna vulgaris heathlands, Anthoxanthum odoratum – Geranium sylvaticum hay meadows, and Nardus grasslands. The species often grows in transitions from heath to grass-dominated communities. The ecology of P. albida in the northern acidic environments is poorly understood. 3. Pseudorchis albida is a perennial geophyte whose populations are maintained predominantly by sexual reproduction, as vegetative spread is limited. The main perennating organ is a highly divided root tuber, which is completely replaced every year. Dormancy – the failure of above-ground parts to appear in a growing season, followed by reappearance of full-sized photosynthetic plants in subsequent seasons – has been observed and typically lasts for one, sometimes 2 years. The adventitious roots and distal parts of the root tuber are colonized by basidiomycetes from the family Tulasnellaceae. 4. The species is pollinated by crepuscular pyralid and pterophorid moths, most likely attracted by the sweet scent. During the day, pollinia can be also transferred by dance flies (Empididae). The breeding system of P. albida is poorly known but high fruit set, often over 90%, raises the possibility of spontaneous autogamy, particularly in arctic-alpine areas. The probability of flowering in consecutive years in P. albida is strongly influenced by cost of flowering and fruiting. 5. Pseudorchis albida has suffered a significant decline in distribution in Britain and other European countries. In Britain, it has been lost from more than 65% of its historical sites, particularly in lowland areas. The main causal factors are the cessation of traditional agricultural practices, habitat fragmentation and disturbance associated with housing and road construction, and agricultural improvement, including reclamation, fertilization and overgrazing. Conservation of remnant populations primarily depends on the maintenance of a short turf by extensive grazing, controlled burning and shrub cutting to promote flowering of adult plants and seedling recruitment.

Sleeping site use of the white-headed langur Trachypithecus leucocephalus: The role of predation risk, territorial defense, and proximity to feeding sites

Abstract We collected data on sleeping site use from two groups of white-headed langurs Trachypithecus leucocephalus living in Fusui Nature Reserve, China between August 2007 and July 2008. This information was used to test several hypotheses regarding ultimate causes of sleeping site use in this primate. White-headed langurs slept either in caves (17 sites) or on a cliff ledge (one site). They used all sleeping sites repeatedly, and reused some of them on consecutive nights; three nights was the longest consecutive use of any one sleep site. We suggest that langurs use sleeping sites to make approach and attack by predators difficult, and to increase their own familiarity with a location so as to improve chances for escape. Langurs’ cryptic behaviors with an increased level of vigilance before entering sleeping sites may also help in decreasing the possibility of detection by predators. Group 1 spent more sleeping nights in the central area of their territory than expected; in contrast, group 2 spent more sleeping nights in the periphery of their territory, which overlaps with that of another groups, than expected. The position of sleeping site relative to the last feeding site of the day and the first feeding site of the subsequent morning indicated a strategy closer to that of a multiple central place forager than of a central place forager. These results suggest that territory defense and food access may play an important role in sleeping site use of white-headed langurs.