Search

Migration is the seasonal habitual movement, exhibited by many avian species along a flyway from breeding to wintering grounds and vice versa all over the world. Migratory birds are very sensitive to even small changes in water level which may be affected by flood or drought on their breeding and wintering grounds. High rains during monsoon season can cause flood conditions in the lower hills and Gangetic plains including Haridwar district. In our study, conducted during last ten years (2009-2018), we covered Bheemgoda Barrage and Missarpur Ganga Ghat of Haridwar, Uttarakhand, where 46 species of Migratory (M) and Resident Migratory (RM) wetland birds were observed. Bird survey indicated that there was a significant increase (p = 0.064, t-test) in the population of certain species such as Bhraminy Shelduck (67%), Black Headed Gull (31%), Gadwall (7%), Northern Pintail (59%), Red Crested Pochard (10%) and Tufted Pochard (47%) in Missarpur Ganga Ghat as compared to Bheemgoda Barrage (based on the average abundance of the species observed during study period). It may be pointed out that after flood and loss of vegetated island, there was significant decrease (p= 0.023, t-test) in the population of species such as Black necked stork (76%), Great crested grebe (56), Pallas gull (47%) at Bheemgoda barrage, while some species such as Bar headed goose, Common pochard did not arrive in Bheemgoda barrage after the flood. The study would help to understand the effect of climatic change on water birds species distribution in natural and man-made wetlands.

Background The Shelduck (Tadorna tadorna) is a characteristic waterbird species of inland wetlands in northeastern Algeria. Its wintering behavior in relation to changes of local abundances and foraging group density is poorly known. Objectives This study aims at monitoring patterns of diurnal activities and the variation of behavioral time-budgets in relation to numbers of wintering Shelducks. We investigate temporal variations of diurnal activities across multiple-time scales and consider their interrelationships. Methods Assessments of local population abundance were weekly surveyed during two wintering seasons (2010–2012), whereas diurnal activities (feeding, sleeping, swimming, preening, loafing, flying, courtship, and antagonism) were studied three times a month during seven hours (08:00–16:00) using the Scan method. Time budget variations of each behavioral activity were tested using nested ANOVAs following multiple time scales. Generalized linear mixed-effects models (GLMM) tested whether variations in diurnal activities were density-dependent. Results During the wintering season, Shelduck’s numbers followed a bell-shaped trend, which indicated that the species was typically a wintering migrant in Sabkha Djendli. The first individuals arrived onsite in October–November then numbers reached a peak in January (up to 2400 individuals in 2012) with steady density during December–February, afterward individuals left the site progressively until late April when the site is deserted. During both wintering seasons, diurnal activities were dominated by feeding (60%), followed by sleeping (12%) then swimming and preening with 9% and 8%, respectively. The rest of the activities (loafing, flying, courtship and antagonistic behaviors) had low proportions of time budget. ANOVAs showed that activity time budgets varied significantly following multiple time scales (year, season, month, day, semi-hour). Time budgets of diurnal activities during each wintering season were significantly interrelated. Correlations patterns between the two seasons were similar. GLMMs revealed that the variations of diurnal activities were not density-dependent, except for preening and swimming. Conclusion During the wintering season, habitats of Sabkha Djendli are important for waterbirds, including the Shelduck that used the lake mainly for food-foraging and resting. The 2400 individuals censused in mid-winter are important locally and at the North African scale. This stresses the need to strengthen the protection status of this wetland and mitigate degradation sources that threaten wintering waterfowl.

Several North African wetlands are classified as wetlands of international importance (Ramsar sites and Important Bird Area) because thousands of Shelducks ( Tadorna tadorna) winter in these habitats. However, Shelduck’s patterns of habitat use in these protected wetlands during the wintering season are still hindered by lack of information in arid and semi-arid regions regarding population dynamics and the effects of climate variables. This ornithological survey aims to study population dynamics and temporal patterns of diurnal activities of the Shelduck at two Ramsar and Important Bird Area sites (Chott Tinsilt and Sebkhet Ezzemoul) with respect to the effect of climatic parameters of the habitat in order to deepen our understanding of wintering strategies and habitat use. Populations were weekly censused from 06:00 to 19:00 during the entire wintering season (September 2015–May 2016). Diurnal behavioural activities were monitored at the same rate, and then the variation of time budget was tested using generalized linear model to determine the effects of climate variables and conspecific density dependence. The Shelduck was observed at both sites from the end of November and remained there until the total desiccation of both lakes in early May. Trends of Shelduck’s population dynamics differed between the two sites. Generalized linear models revealed the significant effects of temperature, wind speed and number of snowy days on population dynamics. Feeding was the main diurnal activity of the Shelduck at both sites with 80.2% of time budget at Chott Tinsilt (mainly feeding at lake shores) and 82% at Sebkhet Ezzemoul (mainly feeding in water). The generalized linear models showed that the variation of time budget allocated to different diurnal activities was not density-dependent, but rather it was negatively affected by the increase of air temperature. Significant effects of the interaction between population size and some climatic variables were found and discussed. During the whole wintering season, Chott Tinsilt and Sebkhet Ezzemoul play an important ecological role since they offer a wide-ranging diurnal forging habitat and a shelter for thousands of this waterfowl.

Ecological theory predicts that if animals with very similar dietary requirements inhabit the same landscape, then they should avoid niche overlap by either exploiting food resources at different times or foraging at different spatial scales. Similarly, it is often assumed that animals that fall in different body mass modes and share the same body plan will use landscapes at different spatial scales. We developed a new methodological framework for understanding the scaling of foraging (i.e. the range and distribution of scales at which animals use their landscapes) by applying a combination of three well‐established methods to satellite telemetry data to quantify foraging patch size distributions: (1) first‐passage time analysis; (2) a movement‐based kernel density estimator; and (3) statistical comparison of resulting histograms and tests for multimodality. We demonstrate our approach using two sympatric, ecologically similar species of African ducks with quite different body masses: Egyptian Geese (actually a shelduck), and Red‐billed Teal. Contrary to theoretical predictions, the two species, which are sympatric throughout the year, foraged at almost identical spatial scales. Our results show how ecologists can use GPS tracking data to explicitly quantify and compare the scales of foraging by different organisms within an animal community. Our analysis demonstrates both a novel approach to foraging data analysis and the need for caution when making assumptions about the relationships among niche separation, diet, and foraging scale.

The winter migratory wetland bird’s diversity of Asan barrage, Uttarakhand, India has been studied during 2005-2012. A total 60 species of wetland birds belonging to 6 orders and 13 families were observed. The findings also hints that Rudy Shelduck Tadorna ferruginea is the most dominant bird followed by Common Coot Fulica atra , Red-crested Pochard Rhodonessa rufina , Common Pochard Aythya ferina and Mallard Anas platyrhynchos . It was observed that Rudy Shelduck preferred Yamuna River waters rather than the traditional still pools, ponds, reservoirs etc. The same trend was displayed by Red-crested Pochard and Great-crested Grebe. On the contrary, winter migratory birds like Northern Shoveller Anas clypeata, Northern Pintail Anas acuta, Common Teal Anas crecca etc were found least in number at Asan Barrage but found in impressive numbers in Haryana traditional pools, ponds. DOI: http://dx.doi.org/10.3126/on.v11i2.9599 Our Nature 2013, 11(2): 192-200

Highly pathogenic avian influenza H5N1 remains a serious concern for both poultry and human health. Wild waterfowl are considered to be the reservoir for low pathogenic avian influenza viruses; however, relatively little is known about their movement ecology in regions where HPAI H5N1 outbreaks regularly occur. We studied movements of the ruddy shelduck (Tadorna ferruginea), a wild migratory waterfowl species that was infected in the 2005 Qinghai Lake outbreak. We defined their migration with Brownian Bridge utilization distribution models and their breeding and wintering grounds with fixed kernel home ranges. We correlated their movements with HPAI H5N1 outbreaks, poultry density, land cover, and latitude in the Central Asian Flyway. Our Akaike Information Criterion analysis indicated that outbreaks were correlated with land cover, latitude, and poultry density. Although shelduck movements were included in the top two models, they were not a top parameter selected in AICc stepwise regression results. However, timing of outbreaks suggested that outbreaks in the flyway began during the winter in poultry with spillover to wild birds during the spring migration. Thus, studies of the movement ecology of wild birds in areas with persistent HPAI H5N1 outbreaks may contribute to understanding their role in transmission of this disease.

Plastic intake by marine vertebrates has been widely reported, but information about its presence in continental waterfowl is scarce. Here we analyzed faeces of waterbirds species (European coot, Fulica atra, mallard, Anas platyrhynchos and shelduck, Tadorna tadorna) for plastic debris in five wetlands in Central Spain. We collected 89 faeces of shelduck distributed in four lakes, 43.8% of them presented plastic remnants. Sixty percent of 10 faeces of European coot and 45% of 40 faeces of mallard contained plastic debris. Plastic debris found was of two types, threads and fragments, and were identified as remnants of plastic objects used in agricultural fields surrounding the lakes. Differences in prevalence of plastic in faeces, number of plastic pieces per excrement and size of the plastic pieces were not statistically significant between waterfowl species. Thus, our results suggest that plastic may also be frequently ingested by waterfowl in continental waters, at least in our study area. Future studies should address this potential problem for waterbird conservation in other wetlands to evaluate the real impact of this pollutant on waterbirds living in inland water. This work was performed within the framework of Project ECOLAKE 00Ecological patterns in endorheic lakes: the keys to their conservation, CGL2012-3890900 , funded by the Spanish Ministry of Economy and Competitiveness, and by the European Union through the European Fund for Regional Development (FEDER) “One way to make Europe”.

Hathnikund is a place in Yamunanagar District in Haryana where Yamuna Rivers forms a sort of Lake over raised plinth after descending into plains from Himalayas nearby Ponta Sahib town near Haryana-Himachal Border. At the same time, Tajewala Barrage is one more pool like scenic place where waters of Western Yamuna Canal are collected by Govt. of Haryana for subsequent multipurpose. In the present studies, wetland bird’s diversity of Hathnikund has been recorded, analyzed and interpreted. The studies were conducted for a period of three years (September 2005-March 2008) during winter season only. The present studies revealed that in all 47 species of wetland birds belonging to 9 orders and 13 families were observed during September 2005-March 2011. Out of these 47 species of wetland birds, 26 species were Winter Migratory, 13 Resident and 9 species were Local Migratory. In so far as Abundance Status is concerned, 26 species of birds were Common, Nine species were UnCommon, Seven Species of birds were Very Common and five species were Rare. Truely winter migratory birds observed belong to Orders, Ciconiiformes, Anseriformes and Chardriiformes. Prominent migratory birds include, amongst others, Bar-headed Goose Anser indicus, Brahminy Shelduck Tadorna ferruginea , Gadwall Anas strepera , Eurasian Wigeon Anas penelope , Mallard Anas platyrhynchos , Northern Pintail Anas acuta , Northern Shoveller Anas clypeata, Red-crested Pochard Rhodonessa rufina , Common Pochard Aythya ferina , Tufted Pochard Aythya fuligula which come to Hathini Kund during winter from far off places like Russia, Siberia, South and East Asia, China and Caspian region. It is recommended that Hathnikund be further promoted as Winter Halting Place for migratory birds by adding islands within the Water Sheet, the construction of wide margins on the peripheral zones and a rich canopy of endemic trees by implanted in plenty. It is further recommended that Eco-tourism facilities be generated at Hathnikund, linking biodiversity with society’s economic upliftment, employment and awareness. It is also recommended that Fish angling sport can be an added attraction to Bird Watching. In correlation with mystery-wrapped natural ambiences of Hathnikund, it can be sold to tourists of foreign origin thus generating exchange earning facility. As of today, no body known about Hathnikund except amateur bird watchers who turn out to be tourists too, if appropriate lodging boarding facilities are available. DOI: http://dx.doi.org/10.3126/ijls.v5i1.5953 International Journal of Life Sciences Vol.5(1) 2011 39-43

Parasitological investigations on 40 gulls ( Larus ), 15 eiders ( Somateria ) and some birds of shelduck ( Tadorna ), curlew ( Numenius ), oystercatcher ( Haematopus ) and terns ( Sterna ) resulted all in all 7 coccidia and about 76 helminth species, partly residenting in different hosts and often in enormous quantities ( Somateria 160.000, Tadorna 58.000, Larus 62.000, Numenius 93.000). Effects of helminthal loads upon the avian hosts, biology of parasites and correlations between their coastal and inland places of residence are in discussion. Morphological differences of Psilochasmus in Tadorna tadorna , of Gymnophallus from gallbladders of Larus too, furthermore the structural change of egg-forming Gymnophallida in the gut of Somateria mollissima and coccid oocysts from kidneys of Larus argentatus , Haematopus ostralegus, Tadorna tadorna and Somateria mollissima are showed.

Evros Delta is the most important wetland habitat in Greece. Thousands of aquatic birdsuse to breed and winter in the area but the reduction of the habitat is still continuing. We used roadtransects and Shelduck Tadorna tadorna habitat selection was recorded. Based on Ivlev’s electivityindex, Shelducks have a preference for places with sweet and salted/brackish waters. Foodavailability and abundance are the key factors that influence the Shelduck movements in Evros Delta.Actions are required to maintain these habitats in order to protect the Shelduck population in thearea.

Summary Morphology and behaviour of hybrids (2 ♀♀ and 1 ♀) of a Goosander ♂ and a Shelduck ♀ is described, and comparisons are made with the parental species. Characters — morphological as well as behavioural — which are similar in the parent species, are unchanged in the hybrid. Those which occur in only one parent species are unchanged in the hybrid, or totally absent, or they occur in a somewhat changed form, i.e. seeming incomplete or, in the case of colouration, being more extended and intense than the parental character. A change in behaviour may, in some cases, be due to an intermediate state in participating structures there being no change in the control of the behaviour. Some characters occur in a somewhat different form in the parent species, and they are found in an intermediate form in the hybrid, or the hybrid possesses the character of one of the parent species. The secondaries of the hybrid are intermediate in that way that some peculiarities of colouration from each of the parents are coupled, and so the colour pattern of the wing becomes different from that of the parent species and similar to the speculum of the Mallard. Some morphological and behavioural characters of the hybrid are different from corresponding characters of the parent species and obviously not intermediate. Some of these may be considered primitive being indicative of ancestral conditions; concerning the behaviour also other features of the hybrid tend to demonstrate a predominance of relatively primitive characters at hybridization. Zusammenfassung Morphologie und Verhalten einiger Mischlinge, 2 ♀♀ und 1 ♂, von einem Gansesager-♂ und einer weiblichen Brandente werden beschrieben und mit den Elternarten verglichen. Die beiden Elternarten gemeinsamen Strukturen, Farben und Verhaltensweisen sind beim Mischling unverandert. Andere, die nur einer der Elternarten eignen, sind beim Mischling unverandert, oder sind ganz verschwunden, oder sie treten in etwas veranderter weiter ausgebreitet als bei der Elternart. Ein abgeandertes Verhalten des Mischlings mus nicht durch eine Anderung der zentralnervosen Kontrolle verursacht sein, sondern ein intermediarer morphologischer Zustand kann daran Schuld sein. Von Merkmalen, die bei den Elternarten ausgesprochen verschieden sind, zeigt der Mischling entweder eine intermediare Form oder nur das Merkmal einer Elternart. Die Armschwingen des Mischlings sind insofern intermediar, als mehrere Farbweisen des einen Elternteils mit einigen des anderen gekoppelt sind. Dadurch wird das Farbmuster ganz anders als bei den Elternarten und wird dem Flugelspiegel der Stockente sehr ahnlich. Einige morphologische Merkmale wie auch einige Verhaltensweisen zeigt nur der Mischling; sie sind offensichtlich nicht intermediar. Manche konnen als ursprunglich angesehen werden. Auch andere Verhaltensweisen des Mischlings deuten auf eine bei Artenkreuzungen bekannte Neigung zum Vorherrschen verhaltnismasig primitiver Merkmale hin.

Summary 1. Overexploited fisheries threaten many species that depend on the exploited resource. Shorebird populations are in decline globally and here we describe how changing shellfishery management and nutrient inputs have had dramatic influence on waterbird communities on an internationally important wetland. 2. Cockle Cerastoderma edule and mussel Mytilus edulis fisheries conflict with shorebirds by removing prey and increasing mortality amongst non-target benthic invertebrates. Under intense dredging pressure, evidence suggests that benthic invertebrates such as worms, with rapid growth and shortgeneration times, should predominate over species such as bivalves, with slower growth and longer generation times. 3. We investigated the change in the waterbird assemblage in the Wash, eastern England, between 1981–1982 and 2002–2003. This period was characterized by heavy fishing pressure on mussels and cockles, ultimately leading to a crash in the mussel stocks. 4. During the study period, the waterbird assemblage underwent a gradual change from one dominated by those species with a high proportion of bivalves or other prey (e.g. crustaceans, fish) in their diet to those with a higher proportion of worms. This gradual change was punctuated by major shifts, corresponding to three winters when oystercatcher Haemotopus ostralegus mortality was 5–13 times normal winter levels. 5. Oystercatcher, knot Calidris canutus and shelduck Tadorna tadorna showed the highest levels of decline. Since the last major oystercatcher mortality event in 1996–1997, the assemblage has not shifted back to that observed prior to the major crash in the mussel stock in 1992. 6. Changes in the waterbird assemblage were significantly related to mussel and cockle stock levels and, to a lesser extent, nutrient levels. Although correlative, evidence from this study indicates that fisheries caused shifts towards a waterbird community dominated by species with a high proportion of worms in their diet. 7. Synthesis and applications. Mechanical shellfisheries directly conflict with the nature conservation interest of sites holding internationally important waterbird populations. Removal of the mussel beds in the Wash led to major shifts in the waterbird assemblage, with a shift towards worm-feeders. Setting annual quotas that provide sufficient food for shellfish eating birds is essenti al to maintain the favourable status of this and other internationally important wetlands where shellfish are exploited.

Numbers of four duck species present within a study area in a tidal embayment (Corner Inlet, south-eastern Australia) were obtained between 1977 and 2002. The species involved were Chestnut (Anas castanea) and Grey (A. gracilis) Teal, Pacific Black Duck (A. superciliosa) and Australian Shelduck (Tadorna tadornoides) and counts are compared with local and distant meteorological data. Chestnut and Grey Teal were most, and Australian Shelduck least, abundant. There was considerable monthly and annual variation; generally, teal and Pacific Black Duck were most numerous in summer and autumn, whereas Shelduck peaked somewhat earlier. Peak abundance corresponded to times of higher inter-annual variation and, apart from Shelduck, abundance had significant, usually weak, negative associations with rainfall though not beyond a one season lag. Pacific Black Duck numbers showed larger, more persistent and positive association with streamflows, particularly in south-eastern Australia, whereas associations for Chestnut Teal were negative and included lags of up to seven seasons. Grey Teal counts showed few significant correlations with streamflow, and Australian Shelduck numbers showed none. Abundance in some species was negatively related to the Southern Oscillation Index in the season of the count, but for Australian Shelduck there was a positive correlation for two seasons previously. Few significant relationships occurred between abundance in Corner Inlet and other Australian waterfowl abundance measures, although annual counts at Corner Inlet were positively correlated with Victorian Summer Waterfowl Counts and negatively with wetland area obtained during East Australia Counts. To an extent, results reflect current views on species' biologies, with birds moving into and out of a saline habitat determined by breeding conditions elsewhere. As found elsewhere, there were some relationships with meteorological variables, though strength and direction varied, perhaps reflecting species' plasticity in responses to rain events at local or distant scale and time.

The egg-laying seasons of various captive waterfowl in the Wildfowl Trust collections at Slimbridge and Peakirk are compared with the situation in the wild. Special attention is focussed on the shelduck and sheldgeese (Tadornini), perching duck (Cairinini), diving duck (Aythyini), sea duck (Mergini), eiders (Somateriini) and stifftails (Oxyurini). Two kinds of response could be distinguished at Slimbridge. In one, egg-laying began sometime in spring, when daylengths reached a stimulatory level, and continued until the corresponding daylengths in summer or autumn were reached, that is, the egg-laying season extended symmetrically on either side of the summer solstice. This is regarded as a “primitive-type” response and is characteristic of phylogenetic lines which are thought to have evolved in, and radiated from, the tropics; the comb duck, muscovy duck, ringed teal and southern pochard are examples. The second kind of response was characterized by the cessation of egg-laying when daylengths still remained stimulatory, that is, a characteristic photo-refractoriness to long days developed, and egg-laying occurred during the first half of the year at Slimbridge. We term this a “temperate-type” response, and examples are provided by nearly all the sheldgeese and shelduck, by the mandarin, Carolina, white-winged wood duck and all Aythya and the sea duck. Only a few examples of apparently intermediate breeding response were noted and these transitional species are discussed, for example the Andean goose, Abyssinian blue-winged goose and Radjah shelduck. The egg-laying cycles can be described as entrained rhythms and their phase angles measured in relation to seasonal daylength changes at Slimbridge. In Aythya, the onset of reproductive activity was strongly correlated with the latitude of origin whereas the end of breeding was not. This was because refractoriness developed at about the same time in all species, even though they began breeding in response to different photoperiods. For this reason, the length of breeding season expressed at Slimbridge was correlated with the midlatitude of the breeding range in the wild but even more strongly with the photoperiod under which egg-laying was initiated. The onset of breeding in the sheldgeese and perching duck was not related to latitude, perhaps because species have had time to modify their ranges. However, the end of breeding in perching duck was related to latitude. Cessation of breeding corresponds to the onset of moult and the secretion of thyroid hormones. We suggest that as waterfowl radiated to higher latitudes their “biological clocks” became entrained to the new light regimes and a host of physiological functions were ordered in an adaptive rather than competitive sequence. It is because so many biological functions are liable to compete for scarce environmental energy supplies that some kind of endogenous partitioning is necessary. This endogenous component is seen when different species are kept under standard lighting conditions. It follows that the photo-response of a species reflects its evolutionary history and so the discussion broaches zoogeographical and taxonomic topics. For example, it seems unlikely that the white-winged wood duck evolved in the tropics, and likely that the sheldgeese and shelduck radiated from a post

Many waders and ducks rely exclusively on invertebrates for their food and can deplete populations of these invertebrates. The mudsnail Hydrobia ulvae and the shelduck Tadorna tadorna are both widespread and abundant and in previous studies H. ulvae has been identified as the main food source for shelduck. The objective of the study was to quantify the predation of shelduck of H. ulvae on an intertidal mud flat in north Wales in order to estimate the contribution of shelduck predation to H. ulvae mortality and to estimate the importance of H. ulvae in the diet of shelduck. The contribution of shelduck towards the observed mortality was estimated from the number of H. ulvae per dropping, the number of droppings produced per hour and the number of shelduck found at the study site. Shelduck predation hardly made a contribution to the observed mortality of H. ulvae. Examination of the energetic requirements of shelduck shows that H. ulvae cannot be a significant part of the diet. In conclusion, the predation of shelduck on H. ulvae was irrelevant for both the population dynamics of the mud snail and for the energy requirements of shelduck in the study area.

Summary Breeding biology of Shelduck was studied in England on the Isle of Sheppey, Kent. Virtually complete separation of breeding and non-breeding sections of the population occurred and non-breeders gathered at two feeding areas which were also the foci of the winter population. Pairing of first spring females usually occurs in the non-breeding flocks and bonds are then of long duration. There is an excess of males throughout the year and during the winter, particularly in February, these attempt to pair up by breaking into established pair bonds. Some probably succeed. Flocks of adults in early April were demonstrated to be potential breeders: such flocks appear to provide mutual stimulation. Smaller, socially discrete groups of breeding adults were discovered and named “communes”. These nested together, held adjacent territories and remained in contact throughout the breeding season, even when most pairs had lost nests. They are considered to be the basic social unit of breeding populations, perhaps of all populations. Breeding birds were unevenly distributed such that the density of all nests was one per 230 acres, but the maximum was 6 per acre. Average clutch size of 10·1 and mode of 8 were found from nest records, compared with 8·8 and 9 respectively deduced from broods of ducklings less than three days old. Egg laying began at the end of April and lasted about 81/2 weeks. Incubation spanned some 10 weeks from early May; individual periods averaged 30 days. An automatic recorder showed that one female spent 87% of the available time incubating. Shelduck were found to be single brooded and no evidence of re-nesting occurred. The brood period started in early June and lasted about 9 weeks. Creching was considered to result mainly from desertion by parents, but over-crowding was also a factor. Fledging takes approximately 61/2 weeks. In 1962 and 1963 approximately 54% and 59% respectively of the summer population attempted breeding. Success in getting broods to water (called duckling success) varied from 23·9% to 73·8% in the period 1960 to 1963. This represented a breeding success of 16% to 49·2%. Duckling losses appeared to be heavy. Shelduck generally breed first in their second spring, but some males may not breed until they are almost five years old.

A brief account is given of the topography and climate of the Sudan and a more detailed survey is made of the vegetation and habitats afforded to wintering Palaearctic migrants in the Sahel and Soudan savannah zones in the central Sudan. Climatic conditions during the migration seasons are mentioned and the utilization of habitats by wintering migrants is broadly surveyed. The status of 196 Palaearctic migrant species is treated briefly. The basic observational data are tabulated to summarize observed patterns of migration in terms of date, relative abundance and region (for which purpose the central Sudan is divided into four from west to east). Hitherto unpublished field notes of the authors and their collaborators are used, together with dated observations (including specimens collected) of earlier authors, to provide the fullest data on each species. Moreau's (1967) paradox is discussed as it relates to the Sahel and Soudan savannah zones in the central Sudan, together with the degree of competition with resident African species in those zones. Some disparities between the spring and autumn abundance and d. istribution of Palaearctic migrants are discussed in relation to 40 species ana some tentative views are advanced on the possible reasons for such disparities. Evidence is adduced which points to Lanius minor and Coraczus garrulus (and possibly Circus pygargus, partially at least) having loop migrations, south through the Sudan and north through Arabia, and Falco wespertinus south through the Sudan and north through West Africa. An explanation is offered for the greater volume of water birds observed migrating down-Nile in spring compared with their volume up-Nile in autumn, and for the reversed situation observed in the region west of the Nile for these same species. Shelduck Tadorna tadorna is included in the Sudan list for the first time.

SUMMARY The food and feeding habits of Shelduck Tadorna tadorna are described, based on the analyses of the viscera of 30 birds collected under special licence, and of 18 birds found dead or dying during the cold weather of 1963, on faecal material from eight incubating birds, on field observations and on the literature. The birds came from a number of different localities and from each month of the year, apart from July. The mollusc Hydrobia ulvae (Pennant) was found in all 46 birds which contained food, and it is quite obvious, and this is confirmed by the literature and by faecal analyses, that this is the most important food item during much of the year and in many different localities. Other species eaten included the bivalve Macoma balthica, the amphipod Corophium volutator, the ragworm Nereis sp., the alga Enteromorpha, and occasionally the seeds of various plants. The importance of H. ulvae is examined in the light of its distribution and numbers, which may be a strong controlling factor in concentrating Shelduck in certain areas at certain times of the year. The feeding behaviour of Shelduck, and a number of other birds, is apparently closely related to the cyclic behaviour pattern of the main food species, H. ulvae. It seems that Shelduck have a rather fixed type of feeding behaviour which exploits only one feeding niche and therein mainly one food item. Any event (prolonged gales or very cold weather) which prevents the bird from using that niche can be the cause of heavy mortality.

SummaryA complete fossil humerus referable to a shelduck (Anatidae: Tadorna sp.) is reported from an uncertain locality in the ‘Bookmark cliffs’ on the River Murray, a few kilometres upstream from Berri and Lyrup southwest of Renmark, in the Riverland region of South Australia. The fossil was embedded in a piece of pale grey, clean coarse sandstone having a siliceous cement. This is interpreted as being Parilla Sand, of late Pliocene age, which outcrops along the Murray River from Renmark to Loxton.