Coexistence of crowned and blackwinged plovers

Summary Coexisting Crowned Plovers Vanellus coronatus and Blackwinged Plovers V. melanopterus were studied to determine whether niche partitioning occurred or was necessary to facilitate their coexistence. The results of this study show that niche partitioning did not occur. We suggest that the association of these two species potentially enhances the ability of each to detect and avoid predation, in spite of any possible deleterious effect of interspecific competition (e.g. reduced per capita food intake).     

The enigma of antipredator behavior in lemurs: Evidence of a large extinct eagle on Madagascar

Numerous zoologists who study diurnal lemurs on Madagascar have noted that they react strongly to the presence of birds of prey. For two of the most intensively studied lemurs, Propithecus verreauxiand Lemur catta,there are few documented cases of raptor predation. Thus, the maintenance of this stereotypic response is enigmatic. Bird bones recovered from cave surface deposits in southwestern Madagascar include the remains of an eagle (Aquila),a genus that has disappeared from Madagascar and that would have been capable of hunting animals the size of adult P. verreauxi and L. catta.The stereotypic response of these two lemurs toward raptors may have been retained from the period when this extinct eagle inhabited the island and is reinforced by rare acts of predation by extant birds of prey.     

SHORT NOTES

Hockey, P.A.R., Plagényi, É.E., Turpie, J.K. &; Phillips, T.E. 1996. Foraging behaviour of Crab Plovers Dromas ardeola at Mida Creek, Kenya. Ostrich 67:33-44.

The foraging behaviour of Crab Plovers is directly analogous to the ‘walk-stop-search-walk’ hunting behaviour of true plovers, and changes slightly depending whether the birds are foraging on sand or in water: they are nonterritorial when foraging. Crabs dominate the diet, but other invertebrates and fish are also eaten. Foraging efficiency increases with age and adults and subadults are able to satisfy their daily energy requirements in a single tidal cycle. The population of Crab Plovers at Mida Creek was much larger in 1994 than in 1992, but in 1994 adults achieved much higher intake rates than in 1992, suggesting considerable year-to-year variation in the carrying capacity of Mida Creek for Crab Plovers. The world population of 43–50 000 birds breeds at very few colonies and the species is thus a potential conservation concern. Because of the relative accessibility of large concentrations of Crab Plovers away from the breeding grounds, we suggest that a programme to monitor numbers and population demography should be targeted at nonbreeding aggregations.     

RELATIVE ABUNDANCE OF CRANES (GRUIDAE) IN THE CAPE PROVINCE

Siegfried, W. R. 1985. Relative abundance of cranes (Gruidae) in the Cape Province. Ostrich 56:101-103.

The results of monthly roadside counts of Crowned Cranes Balearica regulorum, Wattled Cranes Grus carunculatas and Blue Cranes Anthropoides paradisea show that Blue and Crowned cranes occurred most abundantly and densely in the eastern part of the Cape Province in 1965–1966. The Blue Crane's average relative abundance was approximately four times that of the Crowned Crane whose population occupied tend to breed in summer, the Blue Crane slightly earlier than the Crowned Crane. The population of the Wattled Crane was a small relict, occurrin in East Griqualand. Based on a rough estimate, there were about 1000–1500 Crowned Cranes and about 7000–10000 Blue Cranes in the Cape Province in the mid-1960s.     

7.—CORRESPONDENCE

Pepler, D., Martin, M., Fouche, F. &; VAN Hensbergen, B. 1994. Radionuclide analysis of Lesser Kestrels Falco naumanni and the origins of populations overwintering in southern Africa. Ostrich 65: 122–126.

The Lesser Kestrel Falco naumanni has recently shown major population declines throughout its breeding range in the Palearctic Region. In order to propose integrated conservation measures, it is important to establish the origins of the population overwintering in Africa. Nineteen Lesser Kestrels collected from released over Europe after the explosion at Chernobyl in 1986. Results of the radio-activity analysis show that these birds contain levels of ¹³⁴CS and ¹³⁷Cs that is below the detection threshold of the instrumentation. The measured activity of ¹³⁷Cs is a factor 57 lower than the “expected” level of 0,460 Bq/g ash. It is suggested that these birds originate from uncontaminated regions.     

Grey Crowned Crane threat assessment around the wetlands of eastern Uganda

The Grey Crowned Crane Balearica regulorum was uplisted to globally Endangered in 2012. There is urgent need to determine the threats they face at local levels for their conservation. I conducted formal point-count surveys around the wetlands of eastern Uganda and observed no cranes. Groups of cranes were encountered when following directions from local inhabitants. Results from a questionnaire survey suggested that cranes make use of most of the wetlands in the region, and that the birds occur in small flocks averaging 6–8 individuals. Wetland loss through farming was reported to be the main threat, but I also documented poisoning, roost disturbance, and the collection of eggs and chicks. Rigorous conservation and education programs are needed to ensure the long-term survival of cranes and storks in this region.     

THE VOCAL REPERTOIRE OF THE GREY CROWNED CRANE BALEARICA REGULORUM GIBBERICEPS. I: THE TONAL AND THE NON-HARMONIC CALLS

ABSTRACT

The study describes the vocal repertoire of the Grey Crowned Crane Balearica regulorum gibbericeps and speculates on the purpose the calls serve. The repertoire consists of 4 tonal and 7 non-harmonic calls. Chicks have 3 different vocalizations.     

Drinking schedule of four sandgrouse species (<Emphasis Type="Italic">Pterocles</Emphasis> spp.) in relation to sunrise and season

Sandgrouse (Pterocles spp.) are adapted to extreme desert environments. One such adaptation is that males transport water in their abdominal feathers to water the nesting female and hatchlings. Hence, understanding sandgrouse drinking regime and regularly used water holes is of great conservation importance. We studied the arrival of four sandgrouse species at a single water hole in the western Negev Desert, Israel. During our visits, the most numerous species was the Spotted Sandgrouse, and in decreasing abundance, we found Black-bellied Sandgrouse, Crowned Sandgrouse, and Pin-tailed Sandgrouse. Black-bellied Sandgrouse arrived significantly earlier than Spotted Sandgrouse and Crowned Sandgrouse. Spotted Sandgrouse arrival peaked later in the morning than Black-bellied Sandgrouse and Crowned Sandgrouse. The data suggest that this is connected to the absolute number of birds for each of the species which influences their synchronous arrival. Also, we find that the amount of time a species spends at the water hole is influenced by the number of birds present, i.e., the species that stay the longest are also the most numerous. The mean temperature when Spotted Sandgrouse peaked was marginally higher (21.2°C) than recorded for Black-bellied (19.5°C) and Crowned Sandgrouse (19.3°C).     

Die Nahrungsprobleme des Zwergflamingos. Rätselhafte Massensterben an den Salzseen

The Lesser Flamingo is well adapted to the extreme conditions for survival at saline‐alkaline waters in Africa and India. It's preferred food is the cyanobacterium Arthrospira fusiformis, which is able to exhibit mass developments in these waters. During the last two decades, an increasing deficite of healthy food of the Flamingos have been reported. Situation reports from the main distribution areas of the Lesser Flamingos show the negative influence of anthropogenic degradation of the habitats of these birds and their food.     

The energetic implications of precocial development for three shorebird species breeding in a warm environment

We investigated the effect of body size, parental behaviour and timing of breeding on the chick growth and energetics of three precocial shorebird (Charadrii) species in a warm sub-tropical environment: the Kittlitz's Plover Charadrius pecuarius , Blacksmith Lapwing Vanellus armatus , and Crowned Lapwing V. coronatus . The three species exhibited slower growth, longer pre-fledging periods and lower energy expenditure during the pre-fledging period than Arctic and temperate zone relatives of similar size. It was found that relative growth rates of charadriid and scolopacid species increased by 1.77% per degree latitude. Blacksmith and Crowned Lapwings are of similar size (i.e. about 160 g), about four times the mass of Kittlitz's Plovers. Taking body mass into account, the resting metabolic rate and daily energy expenditure of the three study species were similar. The relative amounts of energy needed for chicks to grow from a hatchling to a fledgling were low for the three species studied. The relative amount of energy needed to complete growth in charadriid and scolopacid species increased by 2.54% per degree latitude. Because Crowned Lapwings exhibited faster growth than Blacksmith Lapwings but similar daily energy expenditure we suggest that Blacksmith Lapwings compensate for greater energy expenditure in colder weather by growing more slowly. We suggest that small growth rate coefficient, low resting metabolic rate and low daily energy expenditure are adaptations to lower food availability and milder ambient temperatures in sub-tropical breeding habitats compared to temperate or Arctic regions.     

THE CRESTED CUCKOOS OF SOUTH AFRICA

Boshoff, A. F. &; Palmer, N. G. 1980 Macro-analysis of prey remains from Martial Eagle nests in the Cape Province. Ostrich 51:7-13.

A total of 346 prey items, collected from nine Martial Eagle Polemaetus bellicosus nests in the Cape Province, was analyzed. The importance of e.g. Leporidae and Viverridae in the prey spectrum is emphasized. Young domestic small-stock appear to stand at least as much chance of predation by large eagles as does the natural prey of these birds. Nevertheless stock predation by territorial, mated Martial Eagles was only 8% in this study, with some, at least, probably taken as carrion. The validity of the analysis of prey remains collected from or below eagle nests is discussed.     

Breeding sites and winter site fidelity of Piping Plovers wintering in The Bahamas,a previously unknown major wintering area

Most of the known wintering areas of Piping Plovers (Charadrius melodus) are along the Atlantic and Gulf coasts of the United States and into Mexico, and in the Caribbean. However, 1066 threatened/endangered Piping Plovers were recently found wintering in The Bahamas, an area not previously known to be important for the species. Although representing about 27% of the birds counted during the 2011 International Piping Plover Winter Census, the location of their breeding site(s) was unknown. Thus, our objectives were to determine the location(s) of their breeding site(s) using molecular markers and by tracking banded individuals, identify spring and fall staging sites, and examine site fidelity and survival. We captured and color‐banded 57 birds in January and February 2010 in The Bahamas. Blood samples were also collected for genetic evaluation of the likely subspecies wintering in The Bahamas. Band re‐sightings and DNA analysis revealed that at least 95% of the Piping Plovers wintering in The Bahamas originated on the Atlantic coast of the United States and Canada. Re‐sightings of birds banded in The Bahamas spanned the breeding distribution of the species along the Atlantic coast from Newfoundland to North Carolina. Site fidelity to breeding and wintering sites was high (88–100%). Spring and fall staging sites were located along the Atlantic coast of the United States, with marked birds concentrating in the Carolinas. Our estimate of true survival for the marked birds was 0.71 (95% CI: 0.61–0.80). Our results indicate that more than one third of the Piping Plover population that breeds along the Atlantic coast winters in The Bahamas. By determining the importance of The Bahamas to the Atlantic subspecies of Piping Plovers, future conservation efforts for these populations can be better focused on where they are most needed.     

BREEDING NOTES ON THE BLACK-NECKED GREBE PODICEPS NIGRICOLLIS BREHM

Summary

Tarboton, W. R. &; Fry, C. H. 1986. Breeding and other behaviour of the Lesser Jacana. Ostrich 57: 233–243.

Breeding Lesser Jacanas were studied briefly at Lake St Lucia (Zululand), Hwange (Zimbabwe) and the Okavango Delta (Botswana). The species is monogamous and breeding birds are dispersed as territorial pairs. Male and female share incubation nearly equally, alternating at the nest in shifts averaging 39min; the eggs are attended (incubated or shaded), on average, for 82% of the daylight hours. Eggs are incubated by holding them against the breast with the underside of the wings; at least one chick was seen carried under a parent's wing. The pullus, foraging behaviour, courtship and vocalisations are described. It is suggested that the Lesser Jacana's small egg necessitates a high rate of nest attendance which could account for the sociosexual differences between this species and other jacanas.     

Actual and perceived collision risk for bird strikes at Namibian airports

At Namibia’s two major airports, Hosea Kutako International and Eros (domestic), 117 bird strike collision incidents were recorded between 2006 and 2010. A risk assessment, which included a proposed risk weighting methodology, was conducted at Hosea Kutako and Eros airports, which estimated the probability of an accident/collision as well as the consequence of such a collision. The assessment included surveys of bird occurrence frequencies as well as pilot interviews. The results of the risk assessments were compared with actual bird strike incidences for each species, frequency of occurrence of birds and pilot perceptions of species risk, in order to find whether risk assessment and pilot perception are reliable measures of potential bird strike incidence. White-backed Vulture Gyps africanus and Helmeted Guineafowl Numida meleagris were the highest risk species at both airports. They were also, after Crowned Lapwing Vanellus coronatus, the species most often observed by pilots. Bird strike records showed that Crowned Lapwing and Helmeted Guineafowl were also the most frequently struck birds at both airports. The study illustrates how combining risk assessment, pilot perception and bird strike history can benefit bird strike minimisation plans at airports through the rapid identification of priority bird species.     

THE BREEDING BEHAVIOUR OF THE LESSER FLAMINGO PHOENICONAIAS MINOR

This paper summarizes what has been learned about the breeding behaviour of the Lesser Flamingo Phoeniconaias minor from 1954 to 1969, especially at Lake Magadi, Kenya, in 1962. The only known regular breeding site is on soda mudflats at Lake Natron, Tanzania. Lake Magadi, used in 1962 when Lake Natron was full of water, may only have been used once this century. Breeding has been sporadically reported from other lakes, but reports are usually inadequate and in many cases successful breeding was not proven. At Lake Natron the breeding site is in the middle of the lake which is 70 km long by 24 km wide. Breeding conditions are extremely harsh, mid-day temperatures regularly exceeding 50^oC and reaching 70–75^oC. The advantage of the site lies in its complete freedom from predatory mammals. Details of known breeding, obtained by aerial surveys, are given. Lesser Flamingos do not breed annually, and tend to start in the last quarter, October to December, of any year in which they breed. There is no obvious relation between food supply and this breeding date. The last quarter of the year at Lake Natron tends to be rainy and warm. No really large-scale breeding has been observed since 1962. The methods used for estimating adults and young are given. They have shown good correlation with ground counts at Lake Magadi in 1962. The total population is of the order of three to four million, and the largest known breeding colonies were of 1,100,000 pairs at Lake Magadi in 1962 and 570,000 pairs in 1957 at Lake Natron. From 1953 to 1962 inclusive about 275,000 pairs (1/5 to 1 /6 of the population) bred annually on average, but since 1962 the average number breeding per year has been less, reducing the overall average to perhaps 180,000 pairs. At this rate a pair takes 22–24 years to replace itself. The nuptial display of the Lesser Flamingo resembles in many respects that of the Greater Flamingo Phoenicopterus ruber. When displaying, Lesser Flamingos congregate in a tightly-packed flock, rapidly moving, in which various ritual movements are performed. Display normally takes place in certain sites far from known breeding grounds, and may be stimulated by conditions of very dense population. Lesser Flamingos build mud-mound nests similar to but smaller than those of the Greater Flamingo. Measurements, weights, and other details are given. The huge 1962 Magadi colony involved the excavation of some 20,000 metric tons of soda mud. One egg is normally laid. Large numbers of birds tend to lay synchronously in particular parts of the colony. The threshold numbers for breeding may be of the order of 5,000 pairs. Both sexes incubate, for about 28–29 days. Incubating birds are liable to desert en masse when disturbed, e.g. by hyenas. 70–90% of eggs hatch, usually about 85%. Larger colonies are more successful than smaller, and birds that lay out of phase with others tend to desert without hatching. The development of the young resembles that of the Greater Flamingo, but the two are distinguishable at an early age by bill structure. At Lake Natron the fledging period is about 70 days, but at Lake Magadi it was about 90 days, probably because the parents had to fly to Lake Natron for food. Adults attend the chicks closely for the first week of life, but thereafter leave them increasingly. Chicks more than one week old gather in herds, which eventually aggregate to huge numbers, 300,000 or more. Both at Lake Natron and Lake Magadi the chicks moved en masse out of the breeding area to gathering grounds in shallow water, where they remained till able to feed themselves and fly. Both sexes feed the young with regurgigated liquid matter, delivered bill to bill with parent and young both facing forward, as in the Greater Flamingo. Feeding details were not closely observed at Lake Magadi as most feeding took place after dark. Breeding success has varied from 5 to 75%, averaging 41 to 43% of eggs laid. The 1962 Magadi colony had 33 to 38% breeding success. Mass moult to flightlessness is described. It may occur before, during, or after the breeding season, or without breeding, and normally only at Lake Natron. It lasts six to eight weeks, perhaps three weeks for an individual, and may be controllable in that it did not occur at Lake Magadi in 1962 when its effects would have been fatal for the colony. Predation by large mammals (from lions to jackals) and birds, especially Egyptian and other Vultures, is described and roughly quantified. Predation from all causes may have resulted in 5% loss at the Magadi colony, but at Lake Natron is probably less. Eight thousand young Lesser Flamingos and 80 Greater Flamingos were ringed at Lake Magadi in 1962. Ringing methods are described. Recoveries have been meagre, the most distant being from the Awash Valley, Ethiopia. No rings have been observed among the adult population in recent years. The most probable explanation of the poor results is ring loss through chemical action of the water.     

Predation of birds in mist nets by callitrichids (primates): how to prevent similar events

We report predation of four birds while caught in mist nets and recommend some means of prevention. Two birds were attacked by Callitrhix jacchus and one by Saguinus midas. The predator in the fourth case was unidentified. These cases were relatively rare, affecting 0.4–4.4% of the captured birds. Two of the predated birds were caught more than 1 m above the ground and may have been accessed from branches. The other two were caught close to the ground. Reducing time intervals between net checks and cutting off branches close to nets may reduce bird predation in mist nets.     

Predation of codling moth Cydia pomonella L. by the Silvereye Zosterops lateralis (Latham)

Predation of cocooned larvae of codling moth Cydia pomonella by silvereyes Zosterops lateralis was studied in an apple orchard in Nelson, New Zealand. Apple logs with known larval densities were made available to the birds for known periods of time, either in cages or exposed in the apple orchard. The numbers of silvereyes and the natural predation of codling moth were recorded in the same orchard. Predation was density dependent. On caged logs with an initial high density of 32 larvae, 1.1 larvae were consumed per bird‐hour; in contrast, one larva was consumed per 34.5 bird‐hours at three larvae per log. A curvilinear relationship was demonstrated between larval density and the bird‐hours required for predation; this relationship was consistent with the known density dependence of silvereye predation of codling moth. A regression of the total annual winter bird predation of larvae in the orchard on bird numbers was significant. However, the density dependence of predation resulted in declining rates of predation over the winter as larval density declined; the first birds to arrive in the orchard benefitted from particularly high predation rates. As a consequence, fluctuations in bird numbers during the winter had only a secondary influence on predation rates. The numbers of silvereyes in the orchard showed no relationship to the density of the codling moth population present. This study confirmed the importance of silvereyes in the predation of codling moth and a functional, not numerical, rseponse of these birds to codling moth density.     

Western Snowy Plovers Charadrius alexandrinus nivosus select nesting substrates that enhance egg crypsis and improve nest survival

Predation is an important cause of nest failure for many birds and has shaped the life‐history characteristics of many species, especially ground‐nesting shorebirds. We examined nesting success, causes of clutch failure and nest survival in relation to variation in substrate characteristics in a colour‐marked population of Western Snowy Plovers Charadrius alexandrinus nivosus breeding on riverine gravel bars in coastal northern California. Plovers experienced higher nesting success on gravel bars than on nearby beaches, which were characterized by more homogeneous, sandy substrates. On gravel bars, Plovers nested in habitats characterized by large, heterogeneous substrates, with more egg‐sized stones, compared with random sites. Egg crypsis, as indexed by time required of a naïve observer to detect a nest, increased with number of egg‐sized substrates. Nest survival correlated negatively with heterogeneity of substrates and positively with the number of egg‐sized stones. Consistently high nesting success of Plovers on gravel bars indicates that this high‐quality habitat deserves special management considerations given the species’ threatened status.     

Primary moult,biometrics, mass and age composition of Grey Plovers Pluvialis squatarola in southeastern India

Little is known about the biology of waders wintering in southern Asia; this paper deals with the Grey Plover Pluvialis squatarola, a species extensively studied only in western Europe. Adult Grey Plovers wintering in southeastern India underwent primary moult in autumn; the duration was estimated to be 127 days, with mean starting date 1 September and mean completion date 5 January. Some first-year Grey Plovers initiated primary moult in late winter and spring, and completed this moult the following spring. The average mass of adults on arrival in September was 200 g, fluctuated close to 220 g from October to February, and increased to 280 g near the end of May. The mass variation did not show the January peak observed in western Europe. Breeding productivity, measured as the percentage of first-year birds in winter catches, varied between 5% and 70% over six years, and showed a positive correlation with that of Dark-bellied Brent Geese Branta b. bernicla in western Europe and Curlew Sandpipers Calidris ferruginea in South Africa.     

Influence of environmental factors on the numbers and activity of wintering Lapwings and Golden Plovers

Variations in the numbers and activity of Lapwings Vanellus vanellus and Golden Plovers Pluvialis apricaria using 322 ha of lowland farmland were examined in relation to temperature, rainfall, wind speed and moonphase. The study was undertaken over two winters (1987/88 and 1988/89), with maximum counts of 4000 Lapwings and 820 Golden Plovers. Patterns of occupancy of the study area and seasonal occurrence are described. Temperature and the phase of the lunar cycle seemed to be particularly important in affecting the distribution and activity of the birds. More Lapwings occurred in the study area on the colder and on the wetter days in several months, and also around the full moon period when feeding activity was particularly prevalent. A higher proportion of Lapwings tended to feed on colder days and around the new moon period, while daytime loafing increased around the full moon period. These results support the ideas that birds need to feed more in cold conditions, when energy demands are high, and that night feeding frequently occurs during the full moon period, although the reasons for this remain unclear.