WADER POPULATIONS (CHARADRII) OF THE MARINE LITTORAL OF THE CAPE PENINSULA,SOUTH AFRICA

Pringle, J. S. & Cooper, J. 1977. Wader populations (Charadrii) of the marine littoral of the Cape Peninsula, South Africa. Ostrich 48: 98–105.

Waders (Charadrii) were counted regularly on two stretches of coastline, totalling 5,6 km, on the Cape Peninsula from January 1975 to July 1976. Eight Palaearctic species and seven indigenous species were observed. Arrival of migrants extended from mid-August to January. Autumn departure of Curlew Sandpipers Calidris ferruginea occurred approximately six weeks before departure of Sanderlings C. albu. No overwintering populations of migrant waders were observed. Information is presented which suggests that overwintering Turnstones Arenaria interpres, but not Sanderlings, Maycongregate at a sheltered coastal wetland. Observations of marked birds suggest that individual Sanderlings regularly use particular feeding localities. Populations of indigenous waders showed little seasonal variation in numbers, Flocking was observed in winter.     

DISTRIBUTION AND NUMBERS OF COASTAL WADERS (CHARADRII) IN THE SOUTHWESTERN CAPE,SOUTH AFRICA,SUMMER 1975–76

Summers, R. W., Cooper, J. & Pringle, J. S. 1970. Distribution and numbers of coastal waders (Charadrii) in the southwestern Cape, South Africa, summer 1975–76. Ostrich 48: 85–97. A survey of the distribution and numbers of waders (suborder Charadrii) in the coastal regions of the southwestern Cape was conducted from November 1975 to February 1976. Forty-four coastal wetlands and 49 sections of coastline were visited between the Olifants and Groot-Brak rivers. The estimated total wader population was 119 008 of which 102 841 (86,4%) were Palaearctic migrants. Langebaan Lagoon and the Berg estuary supported the largest numbers. The Curlew Sandpiper Calidris ferruginea and Sanderling Calidris alba were the most numerous species. The abundance of waders was greater on west coast shores than along the south coast.     

WADERS (CHARADRII) AND OTHER SHOREBIRDS AT CAPE RECIFE,ALGOA BAY,SOUTH AFRICA: SEASONALITY,TRENDS, CONSERVATION,AND RELIABILITY OF SURVEYS

Spearpoint, J. A., Every, B. & Underhill, L. G. 1988. Waders (Charadrii) and other shorebirds at Cape Recife, Algoa Bay, South Africa: seasonality, trends, conservation, and reliability of surveys. Ostrich 59: 166–177.

A total of 126 surveys of waders (Charadrii) and other shorebirds were made along 4 km of shore northwest of Cape Recife. The surveys were conducted bv two observers who counted independently of each other. The variability between observers was least for conspicuous species such as Whitefronted Plover, Blacksmith Plover, African Black Oystercatcher, Whimbrel and Grey Plover, but greatest for cryptic species such as Ringed Plover and for species which formed a minority in mixed flocks such as Curlew Sandpiper and Little Stint. Variability of surveys within years and between years is also considered. Turnstones and Sanderlings were the most abundant waders in summer. Of the Palaearctic waders, Turnstones, Grey Plovers, Sanderlings, Greenshanks and Whimbrels overwintered. In contrast, Ringed Plovers, Curlew Sandpipers, and Little Stints rarely overwintered. Little Egrets, Threebanded Plovers and Water Dikkops occurred mainly in winter. It is recommended that surveys to estimate numbers of Palaearctic waders in summer and winter should be conducted in December, January or February and June or July, respectively. Because of three-year cycles in breeding productivity of certain waders, surveys should be extended over at least three years. There was evidence that waders associated with rocky shores increased in numbers during the study period: this coincided with the erosion of sandy beaches near Cape Recife. Density, biomass and daily field metabolic rates, expressed on an area basis, were similar to those in eastern Scotland. Nine species of tern utilized Cape Recife. It is recommended that the bait-collecting regulations be enforced, that vehicles be prohibited on the beach, and that the tern roost and breeding site be fenced off to create a sanctuary.     

Response of waterbird species to fluctuating water levels in tropical coastal wetlands

Recent upsurges in the incidence of dam construction over rivers for farming and hydro electric power in the West African sub‐region is a known promoter of fluctuating water levels on tropical coastal wetlands. Waterbirds, being one of the dominant fauna on wetlands, are key species that can be affected by fluctuating water levels. Waterbird census and water level monitoring at four coastal wetlands in Ghana revealed that different guilds (species assemblages) of waterbirds responded differently to fluctuating water levels. The populations density of birds in guilds 1 (ducks and cormorants), 3 (tactile surface foraging waders), 4 (pelagic foraging waders) and 5 (stalking herons and egrets) significantly (P < 0.05) increased linearly with decreasing water levels. The population density of birds in guilds 2 (visual surface foraging waders) and 7 (fishing terns) responded significantly (P < 0.05) in a second order polynomial function with optimum numbers occurring when water levels were neither too high nor too low. As far as farming and energy requirement are met from these dams, it is important that the ecological needs of waterbirds on wetlands are incorporated into the management of these dams so as to maintain appropriate water levels beneficial to waterbird populations.     

Aspects of population dynamics and feeding by piscivorous birds in the intermittently open Riet River estuary,Eastern Cape,South Africa

Aspects of the population dynamics and feeding activity of piscivorous birds in the small (c. 5 ha) intermittently open Riet River estuary, on the south-eastern coastline of South Africa, were investigated monthly from August 2005 to July 2006. A total of 188 birds of 13 species were recorded, of which six were wading piscivores, four aerial divers and three were pursuit swimmers. The Reed Cormorant (Phalacrocorax africanus) was the numerically dominant species, with a mean of 8.25 (SD ± 7.90) individuals per count. Mean numbers of the Pied Kingfisher (Ceryle rudis) and Giant Kingfisher (Megaceryle maximus) were 3.42 (SD ± 1.20) and 1.17 (SD ± 0.60) individuals per count, respectively. The remaining 10 species revealed mean values <0.5 individuals per count. Breaching events were associated with a change in feeding groups from waders to pursuit feeders, and a decrease in total bird numbers, most likely due to loss of potential littoral zone foraging habitat for waders resulting from reduced water levels. The highest bird numbers were recorded in winter reflecting the migration of large numbers of Reed Cormorant into the system. Monthly food consumption by all piscivorous birds showed large temporal variability, ranging from 26.35 to 140.58 kg per month.     

The interplay between habitat availability and population differentiation: a case study on genetic and morphological structure in an inland wader (Charadriiformes)

Long‐distance migrant waders breeding in the Arctic often have globally structured populations, largely because they were isolated in glacial or interstadial refugia or were restricted to fragmented coastal wetlands in winter. Conversely, inland species using continentally distributed wetlands appear to be less structured (more often panmictic), presumably because they are less likely to have been isolated by multiple refugia or by current events. We analyzed genetic variation in a widely distributed inland species, the ruff (Philomachus pugnax), sampled from seven Eurasian breeding localities, and from migration routes and wintering areas in Europe and Africa. One mitochondrial marker (N = 118) and eight nuclear microsatellites (N = 170) showed: (1) high genetic variation; (2) large genetic distances among mitochondrial (private) haplotypes within breeding populations; (3) the absence of a signature of isolation‐by‐distance; and (4) a distribution of private microsatellite alleles indicating dispersal between Scandinavia and Siberia but not between western and eastern Siberia. These results were consistent with a large refugial population during the Last Glacial Maximum, and postglacial long range expansions spreading ancestral polymorphisms, and not with a stepping‐stone model of gene flow. The divergence between breeding populations in Europe and Siberia was dated to approximately 12 000 years ago. Although genetic population structure is presently statistically non‐existent, support for evolving population structure came from analyses of geographical variation in two relevant phenotypic traits: wing length and the timing of migration. Analysis of 6077 individuals sampled on migration in 2002–08 revealed that, in each year, shorter‐winged birds migrated through significantly later than longer‐winged birds. The late‐passing birds were associated with more westerly breeding localities. In conclusion, the lack of genetic structuring in ruffs (and other inland species we examined) contrasts with strong structuring in many coastal species. This suggests that the ability to use more widely available inland habitat influences the evolution of genetic structure and the maintenance of genetic variation in waders. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 641–656.     

Disturbance does not have a significant impact on waders in an estuary close to conurbations: importance of overlap between birds and people in time and space

Disturbance of wildlife is a potential cause of conservation concern, not least to overwintering waders Charadrii inhabiting estuaries close to conurbations where human recreational and economic activities are often concentrated. Disturbance from people on and alongside intertidal foraging areas could make it more difficult for birds to survive until spring in good condition by reducing the time available for foraging, increasing energy requirements and displacing birds to poorer foraging areas. We adopted a two-part approach to testing whether such significant impacts occurred in a Special Protection Area where disturbance risk was high because of its small size and close proximity to conurbations. In part one, we recorded over the whole estuary during stages of the tidal cycle when part or all of the intertidal zone was exposed and so accessible to waders (i.e. on receding, low and advancing tides): (1) the numbers and activities of people on the intertidal flats and on the adjacent land in those places where people were visible to waders in the intertidal zone and (2) the numbers of waders present and disturbed into flight, the flight distance and flight duration in the ‘overlap’ areas where people did disturb waders. People occurred on < 25% of the 938 ha of intertidal flats, but most waders foraged on mudflats, whereas most people were on sandflats. People on land were visible to foraging waders along < 35% of the 16.5 km of shoreline. Waders and people were therefore substantially separated in space. Within overlap areas, people and waders were often frequently separated in time: for example, people on land mostly disturbed waders when only the upper shore levels were exposed. The average overwintering wader spent < 0.1% of its foraging time during daylight flying away from people and the additional energy expenditure was equivalent to < 0.02% of its daily requirements. The comparison made in part two between our study area and two comparable estuaries showed that the number of visits each day to the overlap areas would need to be 29 or 43 times greater for disturbance to have lowered the birds’ body condition and winter survival. Both parts of the study therefore suggested strongly that the amount of disturbance was too trivial to have a significant impact on waders. It is concluded that: (1) to properly assess disturbance risk to waders, both extensive and intensive observations must be made on the behaviour of people and birds to quantify the extent to which they overlap in space and time, and (2) it should not be assumed that an estuary's close proximity to conurbations, and the presence of large numbers of people in the vicinity of the SPA, necessarily implies a significant disturbance risk to waders.     

Managing coastal grasslands for an endangered wader species can give positive results only when expanding the area of open landscape

The rapid loss of wetlands during the 20^th century has caused a severe decline in the biota associated with these habitats. In Europe, the loss of wet grasslands has seriously affected breeding waders, whose numbers have halved in the past 50 years and remaining populations are facing fragmented, low quality habitats. To improve the remaining sites as breeding grounds for these birds, the exact habitat requirements of the species need to be known. Our study was carried out in Boreal Baltic coastal grasslands in Estonia, where land abandonment has been the main reason behind waders’ population declines in the past decades. Hence, we focus on partially overgrown fields, aiming to ascertain habitat characteristics determining the breeding site selection of meadow birds, especially the endangered Southern Dunlin (Calidris alpina schinzii).We studied the breeding site selection of four wader species (Southern Dunlin, Common Redshank (Tringa totanus), Northern Lapwing (Vanellus vanellus) and Common Snipe (Gallinago gallinago)) in 23 coastal grasslands over two years. We analysed seven habitat characteristics which could influence the breeding habitat selection of these species.Our study demonstrates that breeding sites of all studied wader species are located closer to wet areas and coastline and further away from woodland. Also, the height of the ground level has an impact on the breeding probability, with lower areas favoured. Concerning the Southern Dunlin, our results show that on sites where the species was absent, suitable breeding sites, regarding the distance from woodland edge, were absent. Thus, reforestation of grasslands may be the key reason behind the poor population status of the species. We also demonstrated that proximity of reed beds did not influence the breeding site selection of waders – a result which contradicts current wet grassland management suggestions.Expanding the open landscape, maintaining a large quantity of wet features suitable for foraging and preventing overgrowth of coastline and lower parts of the meadow makes the habitat optimal for breeding waders. Concerning the growth of the population size and spatial distribution of the Southern Dunlin, removal of woodlands adjacent to grasslands is crucial.     

WADERS (CHARADRII) AND OTHER WATERBIRDS AT LANGEBAAN LAGOON,SOUTH AFRICA, 1975–1986

Summary

Underhill, L. G. 1987. Waders (Charadrii) and other waterbirds at Langebaan Lagoon, South Africa, 1975–1986. Osrrich 58: 145–155.

Langebaan Lagoon was surveyed for waterbirds at midsummer and midwinter between 1975 and 1986. The median number of birds counted in summer was 37 500, of which 34 500 were waders (93% of the waders being Palaearctic migrants). Curlew Sandpiper (59,2%), Grey Plover (10,5%), Sanderling (8,3%), Knot (8,1%) and Turnstone (5,7%) were the major components of the summer wader population. The median number of birds in winter was 10 500, of which 4500 were flamingos and 4000 waders. For Palaearctic waders, the median winter population was 11,5% of the median summer population, but varied between 2,5% and 30,1%. For species of wader which breed in the Taimyr Peninsula, Siberia, a three-year cycle in the numbers of birds overwintering was detected, with large numbers in 1977, 1980, 1983 and 1986. Birds feeding on invertebrates consumed 126,9 kJ m^?2 yr^?1, or 24% of the total production of invertebrates. Greater Flamingos have a major impact on energy cycling at Langebaan Lagoon, accounting for 73,3% of the winter energy consumption by the avifauna. Langebaan Lagoon is the most important wetland for waders in South Africa, accounting for about 10% of the coastal wader population of South Africa. At midsummer, about 0,5% of the total wader population of the East Atlantic Flyway is at Langebaan Lagoon, which ranks about 20th in importance for waders on the flyway.     

福建沿海湿地鸻鹬类资源调查

1997年1月～2003年4月,采用直接计数法与航线调查法相结合的方法对福建省海岸湿地的涉禽进行了调查,共发现鸻鹬类43种及亚种计56386只。结合以往的调查记录,得知福建沿海鸻鹬类共53种及亚种,占全国该类群总种数的62％。冬候鸟和旅鸟是本地鸻鹬类中占优势的生态类群。目前沿海滩涂的围垦和鸟类食物的减少,是鸻鹬类所面临的主要威胁。尽快制定湿地保护与合理利用的规划,对福建沿海湿地鸟类的保护至关重要。闽江口湿地不仅是鸻鹬类集中分布的区域,同时也是世界珍禽黑脸琵鹭(Platalea minor)重要的停歇地,应尽快建立闽江口湿地自然保护区。     

Population‐wide body mass increment at stopover sites is an unreliable indicator of refuelling rates in migrating waders

Estimates of refuelling rates in migrating waders are best based on intra‐seasonal recaptures of individually marked birds. This method, however, has methodological problems associated with capture effects and difficulties in attaining sufficient sample sizes. An alternative method had been proposed whereby refuelling rates are approximated by the body mass increment from the slope of the regression between body masses of all birds caught at a site and date. We investigated the appropriateness of this indicator with a simulation study in non‐synchronized migratory species (i.e. arrivals and departures of individuals at the stopover site are not synchronized). Simulation results indicated that the mass increment across the population may be used as an approximation of refuelling rate only in populations with low turnover rates (percentage of birds arriving at/departing from stopover site per day <2%) and ideally with constant numbers of staging birds. The mass increment of non‐synchronized populations with moderate or high turnover rates (higher than 5%) depends mainly on body masses of arriving birds and is not indicative of the individual rate of refuelling. The results of the simulation study were confirmed with empirical data gathered from Wood Sandpiper Tringa glareola and Common Snipe Gallinago gallinago during their autumn migration at a stopover site in Poland. The population mass increment methods considerably underestimated refuelling rate obtained from the recapture‐based approach of individual birds in both species. As a consequence, we suggest that population mass increment should not be used as an indicator of refuelling rates in non‐synchronized stopover populations of migrating waders.     

The costs of migration: Injuries in migratory waterbirds along the west coast of India

The long distant, transcontinental migration of shorebirds entails many well identified costs in terms of time, energy, and direct mortality risk. Injuries from debris or from human structures and activities were observed as the major reasons for the direct mortality of shorebirds during migration worldwide. We recorded injured birds in major coastal wetlands of Kerala, for a period of 15 years from 2005 to 2019. The injured birds were observed in 9 different sites in various districts of Kerala. The highest instances of injuries were observed in Kadalundi-Vallikunnu Community Reserve, the major wintering and stop over site of migrant shorebirds in the west coast of India. During the study period, fifty-eight individuals of shorebirds belonging to four families were found to be injured. The highest proportion of injuries was recorded among the families Scolopacidae and Charadriidae comprising long distance migrant shorebird species and the lowest among Laridae and Ardeidae. We recommend that environmental authorities pay special attention to minimize anthropogenic debris along the flyways used by migratory birds thereby reducing the risk of injuries to some of these species. Proactive measures such as removal of discarded fishing gear or plastic debris from wintering areas as well as stopover areas could greatly reduce injuries in migratory birds arising from anthropogenic sources.     

雷州半岛湿地水鸟区系组成及生态分布的初步研究

1998年10月至2000年6月,对雷州半岛湿地水鸟区系组成及生态分布进行了调查,结果表明,雷州半岛湿地水鸟56种,隶属7目9科,种类最多的是鹭类（Ardeidae)、鸭类（Antidae)和Xin鹬类（Charadriidae and Scolopacidae),共有41种,56种水鸟中,古北界成分35种,占绝对优势;东洋界、广布种分别只有13和8种。以冬候鸟为主,共有33种;留鸟、族鸟和夏候鸟分别占13、7和3种。冬候鸟主要是鸭类和Xin鹬种类,留鸟主要是鹭类,本地的鸥类（Laridae)几乎都是冬候鸟,受各种协定或法规保护的水鸟有38种。雷州半岛的水鸟主要人布在沿海滩涂湿地,共有49种,红树林是最重要的水鸟栖息地,分布在这里的水鸟有37种。     

1. BIRD-LIFE AT THE ORANGE RIVER MOUTH

Kalejta, B. 1993. Diets of shorebirds at the Berg River estuary, South Africa: spatial and temporal variation. Ostrich 64: 123–133.

The diets of three common migrant waders; Curlew Sandpiper Calidris ferruginea. Grey Plover Pluvialis-squatarola and Greenshank Tringa nebularia and three resident species, Blacksmith Vanellus armatus, Kittlitz's Charadrius pecuarius and Whitefronted Plovers C. marginatus, were studied at the Berg River estuary, South Africa from December 1987 to April 1989. Direct observations of feeding were combined with analyses of stomach contents, pellets and droppings. Nereid worms, Ceratonereis erythraeensis and C. keiskama, were the principal food of all species studied except Greenshanks, which fed mostly on crabs, Hymenosoma orbiculare. Despite considerable overlap in the diets of all bird species, there were differences in the size classes of nereids taken by different bird species. Visually-foraging plovers (Charadriidae) were highly selective, feeding on the largest nereids regardless of their abundance. Tactile foragers, represented by Curlew Sandpipers, were non-selective, and consumed different size-classes of worms in proportion to their abundance in the substratum. Seasonal variations in the diet of waders are linked to seasonal changes in the availability of prey species.     

Use of sandbanks by terns in Queensland,Australia: a priority for conservation in a popular recreational waterway

Many terns (Laridae) from the northern hemisphere overwinter in Australia, but they are rarely covered comprehensively in bird counts in Australian coastal waterways. We conducted censuses over 3 years on terns in an increasingly popular recreational waterway at the northern end of Moreton Bay, known as Caloundra sandbanks, to provide the first overview of the relative abundance of non-breeding tern species on estuary-type sandbanks in Australia. The maximum number of birds counted was > 43,000, of which over 90% belonged to six species of terns. The most abundant tern species was the common tern Sterna hirundo longipennis which reached > 38,000 in one Austral summer. Other northern-breeding migrant terns were the white-winged black tern Chlidonias leucopterus ( > 17,000) and the little tern S. albifrons sinensis ( >11,000), which also breeds in Australia. These migrant terns arrived at Caloundra sandbanks at around late-October and a vast majority had departed by mid-April. Numbers were generally highest from late-December through to early-April. An additional three Australian-breeding terns of smaller population sizes frequented the sandbanks. Density of terns using the habitats could reach a peak of 600 ha⁻¹ during the warmer months of the year, coinciding with peak human recreational activities. In light of the results, Caloundra sandbanks should be regarded as an Area of International Importance based on criteria contained in the Ramsar Convention. The situation at Caloundra sandbanks presents challenges to recreational and tourism issues, requiring review of traditional government priorities in the conservation of wetlands based primarily on waders.     

Oiling rates and condition indices of shorebirds on the northern Gulf of Mexico following the Deepwater Horizon oil spill

The coastline of the Gulf of Mexico in the United States is an important wintering and stopover region for migratory shorebirds. The Deepwater Horizon oil spill (April–August 2010) impacted more than 1700 km of this coastline and could potentially affect shorebirds through long‐term exposure to toxins, degraded habitats, and altered food chains. We investigated the exposure to Deepwater Horizon oil of seven species of shorebirds that winter or stopover along the northern Gulf of Mexico. From October 2010 to May 2012, we captured and banded 691 shorebirds at six sites that experienced varying levels of oil contamination. Of birds sampled, 22 were lightly oiled, with species that forage on the coast having higher rates of oiling than those that forage in more estuarine habitats. Although only 8.6% of birds captured from October 2010 to May 2011 and 0.6% of the birds captured from August 2011 to June 2012 showed signs of oiling, an unknown, but potentially larger, number of shorebirds were likely exposed to indirect effects of the spill, such as decreased foraging time due to oiling of sites or disturbance from cleanup activities. Fuel stores and fattening rates of Dunlins (Calidris alpina) during spring migration, as measured using plasma metabolites, were not influenced by site oiling level. However, the level of disturbance at study sites was a significant predictor of both fuel stores and glycerol levels, suggesting that Dunlins stopping over during spring migration may have had difficulty reaching necessary fuel stores in spring 2011 due to disturbance from cleanup activity on oiled beaches. These effects from disturbance were only observed at sites with high cleanup activity, suggesting that the impact of oil‐spill cleanup on shorebirds may be minimized by limiting cleanup activities to specific areas and times of day.     

Numbers, geographic distribution and habitat utilization of waders (Charadrii) in spring on the shores of Iceland

The occurrence of waders m spring (breeding as well as migrating species) in the intertidal zone was studied along the shores of Iceland Ground surveys were made at a total of 115 sites on the west coast in May 1986 and 1987 Repeated counts in the same season were conducted at 76 sites visited m both early and late May 1987 Furthermore, an aerial census covering most of the Icelandic coastline was carried out in May 1990 (76% of the total coastal length of 6650 km and 92% of the total intertidal area of 445 km² were covered from the air) Altogether 345 000 waders were recorded, including 270 000 knot Cahdrts canutus Geographic distribution was uneven, as is the distribution of intertidal areas, with over 85% of all waders occurring on the west coast where >80% of suitable intertidal habitats are found A majority of the knot population, possibly about half of the turnstone Arenaria interpres population and probably only a minority of the sanderling C alba population wintering in the Palearctic and breeding in Greenland/Canada use Iceland as a staging post on their spring passage The local breeding populations of waders and the High Arctic wader populations on passage have rather well separated time schedules for their utilization of intertidal habitats in Iceland Between them the three above-mentioned species of passage migrants show considerable differences m geographic distribution and habitat utilization during the spring staging period m Iceland     

Evaluating behavioral responses of nesting lesser snow geese to unmanned aircraft surveys

Unmanned aircraft systems (UAS) are relatively new technologies gaining popularity among wildlife biologists. As with any new tool in wildlife science, operating protocols must be developed through rigorous protocol testing. Few studies have been conducted that quantify the impacts UAS may have on unhabituated individuals in the wild using standard aerial survey protocols. We evaluated impacts of unmanned surveys by measuring UAS‐induced behavioral responses during the nesting phase of lesser snow geese (Anser caerulescens caerulescens) in Wapusk National Park, Manitoba, Canada. We conducted surveys with a fixed‐wing Trimble UX5 and monitored behavioral changes via discreet surveillance cameras at 25 nests. Days with UAS surveys resulted in decreased resting and increased nest maintenance, low scanning, high scanning, head‐cocking and off‐nest behaviors when compared to days without UAS surveys. In the group of birds flown over, head‐cocking for overhead vigilance was rarely seen prior to launch or after landing (mean estimates 0.03% and 0.02%, respectively) but increased to 0.56% of the time when the aircraft was flying overhead suggesting that birds were able to detect the aircraft during flight. Neither UAS survey altitude nor launch distance alone in this study was strong predictors of nesting behaviors, although our flight altitudes (≥75 m above ground level) were much higher than previously published behavioral studies. Synthesis and applications: The diversity of UAS models makes generalizations on behavioral impacts difficult, and we caution that researchers should design UAS studies with knowledge that some minimal disturbance is likely to occur. We recommend flight designs take potential behavioral impacts into account by increasing survey altitude where data quality requirements permit. Such flight designs should consider a priori knowledge of focal species’ behavioral characteristics. Research is needed to determine whether any such disturbance is a result of visual or auditory stimuli.     

Occurrence and abundance of waterbirds at an ephemeral pan in the Northern Cape Province,South Africa

Bi-monthly counts of waterbirds were made between March and September 2003 at an ephemeral pan in the Northern Cape Province following the first substantial inundation since 1988. Bi-annual counts between 1991 and 2003 indicated that the pan infrequently supported waterbirds, with waterfowl and small waders generally being the dominant species. During the bimonthly counts, a total of 50 waterbird species was recorded, with the most dominant species, both in terms of numbers and duration of presence, being Black-winged Stilt Himantopus himantopus (max. 378), Cape Shoveller Anas smithii (max. 260) and South African Shelduck Tadorna cana (max. 200). Most other waterfowl and wader species were regular but in lower numbers. Species groups that occurred in limited numbers or for short periods include primarily herons, grebes, flamingos, ibises and storks. Species abundance and richness reached a peak one month after the pan was inundated, followed by a gradual decline over the ensuing two months.     

A STUDY OF THE CINNAMON-BREASTED ROCK BUNTING Fringillaria tahapisi tehepisi

Brown, C. J. &; Piper, S. E. 1988. Status of Cape Vultures in the Natal Drakensberg and their cliff site selection. Ostrich 59:126-136.

Ground, aerial and questionnaire surveys on the status of the Cape Vulture Gyps coprotheres in the Little and High Drakensberg mountain ranges of Natal were carried out from 1981–1983. The area supported at least 1325 Cape Vultures, 60% on the High Drakensberg in 17 nesting colonies (mean of 31 birds per colony) and 38 roosts (mean of 7 birds). In the Little Drakensberg 17 sites were found, six of which were confirmed nesting colonies (mean of 53 birds) and seven were roosts (mean of 16 birds). A minimum of 215 nests was recorded while the actual number of breeding pairs was probably about 325. In the Natal Drakensberg 84% of nests and 77% of roosting birds occupied ledges that faced between east and south, on the lee side of the generally westerly and northwesterly “Bergwind”. Nesting ledges in the High Drakensberg were on average about 100 m lower than roosting ledges. The northern Drakensberg supported the largest numbers of Cape Vultures (19 birds per 10 km of cliffs), while the smallest numbers were recorded in the south (8 birds per 10 km of cliffs). In the south smallstock farming predominates and the availability of carrion is higher than in the north where mainly largestock are farmed. The use of poisons (mainly strychnine) for killing mammalian predators on farms is considered to be the main reason for fewer birds occurring in the south, and is the main threat to Cape Vultures in the Natal Drakensberg.