The isolation and characterization of Campylobacter jejuni subsp. jejuni from domestic geese (Anser anser)

AIMS: The objectives of this study were to determine the presence of thermophilic Campylobacter spp. in free range domestic geese, and to characterize isolated strains using phenotyping criteria and SDS-PAGE of whole-cell proteins. METHODS AND RESULTS: Forty cloacal swabs from two different flocks of domestic geese were examined. All Camp. jejuni strains isolated from geese were biotyped using the Lior biotyping scheme. Twelve Camp. jejuni isolates were also tested for their susceptibility to 17 different antibacterial agents by a disc diffusion METHOD: Fourteen of the isolates were also subjected to SDS-PAGE. All of the geese examined were found to harbour Camp. jejuni. Six geese carried more than one species of Campylobacter. All strains examined were susceptible to various antibiotics but resistant to penicillin G and cephalothin. Eleven strains (92%) were resistant to sodium cefuroxime, and eight (67%) were resistant to cloxacillin, ampicillin and colistin sulphate. Three strains (25%) were resistant to tetracycline, and one strain was resistant to sulfamethoxazole/trimethoprim and kanamycin. Nine strains were subtyped as Camp. jejuni subsp. jejuni biotype II and the remaining ones as biotype I. There were 96% and 100% similarities between all the strains examined by SDS-PAGE. CONCLUSION: This study showed that Camp. jejuni were common in the intestinal tract of domestic geese. SIGNIFICANCE AND IMPACT OF THE STUDY: Geese should be considered as potential reservoirs for human and animal campylobacteriosis. The antibiotic resistance data from this study also showed that fluoroquinolone resistance, which appears to be a problem in poultry isolates in some countries, is not yet a problem in these geese.     

The paradox of extreme high-altitude migration in bar-headed geese Anser indicus

Bar-headed geese are renowned for migratory flights at extremely high altitudes over the world''s tallest mountains, the Himalayas, where partial pressure of oxygen is dramatically reduced while flight costs, in terms of rate of oxygen consumption, are greatly increased. Such a mismatch is paradoxical, and it is not clear why geese might fly higher than is absolutely necessary. In addition, direct empirical measurements of high-altitude flight are lacking. We test whether migrating bar-headed geese actually minimize flight altitude and make use of favourable winds to reduce flight costs. By tracking 91 geese, we show that these birds typically travel through the valleys of the Himalayas and not over the summits. We report maximum flight altitudes of 7290 m and 6540 m for southbound and northbound geese, respectively, but with 95 per cent of locations received from less than 5489 m. Geese travelled along a route that was 112 km longer than the great circle (shortest distance) route, with transit ground speeds suggesting that they rarely profited from tailwinds. Bar-headed geese from these eastern populations generally travel only as high as the terrain beneath them dictates and rarely in profitable winds. Nevertheless, their migration represents an enormous challenge in conditions where humans and other mammals are only able to operate at levels well below their sea-level maxima.     

Causes of the redistribution of Pink-footed Geese Anser brachyrhynchus in Britain

The numbers of Pink-footed Geese Anser brachyrhynchus wintering in Britain have been increasing exponentially since the 1950s. The numbers of geese at virtually all roost sites have increased, but the most dramatic increase has been in Norfolk, the southernmost region occupied in Britain. This redistribution was most likely caused either by the increase in the population forcing greater numbers of geese towards more southerly sites as the result of a buffer effect, by a decrease in the quality of sites elsewhere in the range or by an increase in the attractiveness of Norfolk. Co-ordinated counts of geese around Britain and historical data of changes in agricultural practice in Norfolk were used to examine these possibilities. No evidence was found for buffer effects, degradation of sites elsewhere or an increase in food availability in Norfolk. The major difference between Norfolk and other Pink-footed Goose sites is in the food type available in Norfolk, namely harvested Sugar Beet Beta vulgaris remains. This food is of high quality and the geese are not disturbed whilst feeding on it because of its limited commercial value. The pattern of redistribution of Pink-footed Geese may therefore be the result of cultural learning of the benefits of feeding on Sugar Beet.     

The constraint on habitat use in wing-moulting Greylag Geese Anser anser caused by anti-predator displacements

During the flightless period of wing-moult, terrestrial feeding waterbirds tend to forage close to water. Wing-moulting Greylag Geese Anser anser feeding in a Danish saltmarsh were no exception to this pattern as none fed more than 175 m from the sea. An individual-based stochastic model of goose feeding distribution derived from empirical data showed that requirements for drinking water could not explain the coastal feeding distribution as the model predicted that 57% of all goose observations would be more than 175 m from the sea. The availability of Common Saltmarsh Grass Puccinellia maritima , the preferred food item, could partly explain the exploitation pattern of geese but not the absence of geese from inland feeding areas. Furthermore, the results did not support the hypothesis that geese actively avoided inland feeding areas because of elevated costs from vigilance. The frequency of anti-predator displacement to the sea was the most likely explanation of the feeding pattern. A model that included such displacements predicted that 99% of all geese would feed less than 175 m from the sea. As anti-predator displacement put the most severe constraints on the feeding distribution, predation risk and level of disturbance were suggested to be the overall factors, which determine the choice of moult site in wing-moulting geese.     

印度Ladakh地区斑头雁的数量、种群结构和栖息地利用

于 1998、 2 0 0 0和 2 0 0 2年在印度的Ladakh地区进行了野外考察以研究斑头雁的繁殖行为和种群大小。Ladakh地区的斑头雁集小群在淡水湖泊中的小岛上进行繁殖 ,不在树上和悬崖上繁殖。 5月份开始产卵。群内孵化的同步性较低。盐水湖岸上没有观察到进行繁殖或带有幼雏的斑头雁。作者所调查的Ladakh地区有 35 0 - 10 0 0只斑头雁 ,该物种的数量满足了Ramsar公约的有关规定 ,建议将该地区列为国际重要地区     

Predicting Current Reproductive Success of Goose Pairs Anser indicus from Male and Female Reproductive History

A multiple regression analysis of current reproductive success (goslings fledged) on three male and female life-history traits (age, previous breeding periods, previous successes) was carried out for 31 semicaptive pairs of barheaded geese Anser indicus. Of the female variables, age proved positively and the number of previous nesting periods negatively related to current success. The latter relationship suggests that incubation has costs in terms of future fecundity for the female. Of the male variables, age was negatively and the number of previous fledging successes positively related to current reproductive success. Attempts with additional data to explain these findings in the male either by a positive feedback of success on future success or by differences in male quality gave inconclusive results, as did earlier attempts to demonstrate reproductive costs in geese and swans. In monogamous species with long-term pair bonds, where male and female share most of their life history but specialize in different activities, reproduction may affect the sexes in different ways. If the correlations between life-history traits of mates are not accounted for, individual strategies or constraints may be obscured by opposing effects in the mate.     

Effects of wintering greylag geese Anser anser on their Scirpus food plants

Herbivory of Scirpus litoralis and 5 mantimus tubers by wintering greylag geese, Anser anser, was studied at the marshes of the Guadalquivir in southwestern Spain Exclosures were constructed to compare plant growth m grazed and in grazed sites Scirpus luoralis tubers are clustered, with clusters being interconnected by rhizomes Scirpus mantimus tubers develop individually, and are connected by rhizomes The geese forage on individual S mantimus tubers but take entire clusters of S litoralis tubers, from which only one tuber is normally consumed The reproductive mode of S mantimus, the main food plant of the wintering geese, was dependent on tuber size The proportion of tubers whose shoots bear inflorescences decreases with increasing tuber size, and the larger tubers reproduce vegetatively The geese feed on the smaller S mantimus tubers and the smaller S litoralis clusters Reasons for this preference may be that these tubers and clusters are easier to extract and also that small tubers require less time to break down in the gizzard The number of shoots of S litoralis and S mantimus in grazed sites was 88% and 32%, respectively, compared with that in ungrazed sites Nevertheless this difference reflects m part a decrease of 5 litoralis inside some exclosures during a five years period The length of shoots of both species was shorter in grazed than in ungrazed sites The size-related selection of tubers by geese may have a profound effect on the structure and dynamics of these plants populations, and the trade-off between sexual and asexual reproduction However, due to the clonal nature of the plants, interpretation of plant-goose interactions from an evolunonary perspective is difficult because of the elusive unit of selection involved     

Size-related consumption of Scirpus maritimus tubers by greylag geese Anser anser explained by their functional response

To explain the preference of wintering greylag geese Anser anser for small Scirpus maritimus tubers (<10mm) over larger ones, our hypothesis was that the former would provide higher intake rates. This 'consumption rate hypothesis' was tested experimentally by deriving the functional responses of geese feeding on tubers of three contrasting sizes. Goose consumption rates were measured as: (i) feeding rate (tubers/min) and (ii) instantaneous intake rate (g fresh weight/min) on various tuber densities (5-200 tubers/tray). Geese had linear functional responses over the range of tuber densities offered, and tuber size affected their consumption rate. The results were then used to re-examine intake rates according to relative biomass of tubers found in the wild. In support of our hypothesis, the larger tubers allowed the lower intake rates. Foraging mechanisms that possibly control the tuber ingestion rate of geese were explored. After controlling (through chemical analyses) that nutritional components of tubers do not differ between sizes, it was concluded that geese preference is mainly due to size-related constraints (i.e. handling time) on their ingestion rates. Additional limiting factors (tuber extraction, digestion capacity) which are likely to constrain food intake of wild geese are also discussed.     

Pre-nesting feeding selectivity of Pink-footed Geese Anser brachyrhynchus in artificial grasslands

The pre-nesting feeding ecology of Pink-footed Geese Anser brachyrhynchus was studied in southern Iceland in April and May 1989–1992. Extensive surveys showed that prior to movement to their nesting areas in the interior, Pink-footed Geese fed mainly on intensively managed grasslands of the southern lowlands. Faecal analysis showed that geese feeding in hayfields foraged almost exclusively on the most commonly reseeded species, Timothy grass Phleum pratense , which made up the majority (41% by number of green shoots) of new growth in studied hayfields. Dropping counts, as an indicator of goose use, were highly significantly correlated in all years with density of growing Phleum shoots in individual field units. Geese showed a response in feeding patterns to changes in Phleum density as a result of reseeding patterns. Analysis of forage quality in 1991 showed that Phleum shoots had a higher protein content than all other grasses present in hayfields, with the exception of Deschampsia caespitosa. The latter species showed similar levels of protein, but its tussocky nature precluded effective grazing by the geese. Phleum was similar in fibre content to other common grasses. Based on removal of tagged plants, geese grazed predominantly on the youngest leaves of Phleum , which also had higher protein content and lower fibre than older leaves and attached dead leaves, which were rarely taken by geese. Geese grazed shorter length classes of youngest leaves, which showed higher protein content than longer, older terminal leaves. Recently created grassland habitat has increased the opportunities for female geese to supplement their reserves during the crucial prelude to clutch initiation by selecting the highest quality plant species and the most nutritious parts of that forage.     

Climate change,phenology, and habitat degradation: drivers of gosling body condition and juvenile survival in lesser snow geese

Nesting migratory geese are among the dominant herbivores in (sub) arctic environments, which have undergone unprecedented increases in temperatures and plant growing days over the last three decades. Within these regions, the Hudson Bay Lowlands are home to an overabundant breeding population of lesser snow geese that has dramatically damaged the ecosystem, with cascading effects at multiple trophic levels. In some areas the overabundance of geese has led to a drastic reduction in available forage. In addition, warming of this region has widened the gap between goose migration timing and plant green‐up, and this ‘mismatch’ between goose and plant phenologies could in turn affect gosling development. The dual effects of climate change and habitat quality on gosling body condition and juvenile survival are not known, but are critical for predicting population growth and related degradation of (sub) arctic ecosystems. To address these issues, we used information on female goslings marked and measured between 1978 and 2005 (4125 individuals). Goslings that developed within and near the traditional center of the breeding colony experienced the effects of long‐term habitat degradation: body condition and juvenile survival declined over time. In newly colonized areas, however, we observed the opposite pattern (increase in body condition and juvenile survival). In addition, warmer than average winters and summers resulted in lower gosling body condition and first‐year survival. Too few plant ‘growing days’ in the spring relative to hatch led to similar results. Our assessment indicates that geese are recovering from habitat degradation by moving to newly colonized locales. However, a warmer climate could negatively affect snow goose populations in the long‐run, but it will depend on which seasons warm the fastest. These antagonistic mechanisms will require further study to help predict snow goose population dynamics and manage the trophic cascade they induce.     

Costs and benefits of flocking in foraging white-fronted geese (Anser albifrons): effects of resource depletion

This study investigated the costs and benefits of flocking in white-fronted geese Anser albifrons foraging on rice grains in Japan. The time budgets of focal geese were recorded, and the effects of flock size on the proportions of time spent in vigilant and agonistic behaviour were tested. The results showed that the decline in vigilance level and consequent increase in foraging time were beneficial results of flocking whereas agonistic interactions, a potential cost of flocking, did not increase with increasing flock size. However, seasonal variation in flock size suggested that exploitative competition could be a cost of flocking; the sizes of flocks in spring, when resource depletion had progressed, were significantly reduced compared with those in autumn. An experimental increase in rice density resulted in a significant increase in flock size. We conclude that the flock size of foraging white-fronted geese is a result of compromise between a constant benefit of flocking (i.e. decline in vigilance level) and a cost of flocking varying with food abundance (i.e. exploitative competition).     

Lack of competition between barnacle geese Branta leucopsis and pink-footed geese Anser brachyrhynchus during the pre-breeding period in Svalbard

The feeding ecology of barnacle geese and pink-footed geese was studied in Sassendalen, Svalbard during the pre-nesting period (late May) to assess the potential for inter-specific competition. Barnacle geese fed almost exclusively (97%) by grazing above-ground plant material, mostly (79%) along snow edges in moss-mat habitats. Pink-footed geese fed mostly (93%) by excavating below-ground parts of plants, mostly (56%) away from snow and were more evenly distributed between habitat types. Barnacle goose faeces contained mostly (62%) moss, that of pink-footed geese mostly (48%) below-ground plant storage organs (especially Bistorta viviparum L.). Principal components analysis of dropping contents showed no overlap in species diet in allopatry or sympatry. There was little overlap in diet and feeding ecology of the two species at this pre-nesting feeding site. Hence, unless increased goose feeding densities affect future vegetation density and composition, under present circumstances, increasing numbers of either species is unlikely to affect foraging conditions for the other at this important stage in the annual cycle. However, such changes could have local density-dependent intra-specific effects.     

Chewing Lice of Swan Geese (Anser cygnoides): New Host-Parasite Associations

Chewing lice (Phthiraptera) that parasitize the globally threatened swan goose Anser cygnoides have been long recognized since the early 19th century, but those records were probably biased towards sampling of captive or domestic geese due to the small population size and limited distribution of its wild hosts. To better understand the lice species parasitizing swan geese that are endemic to East Asia, we collected chewing lice from 14 wild geese caught at 3 lakes in northeastern Mongolia. The lice were morphologically identified as 16 Trinoton anserinum (Fabricius, 1805), 11 Ornithobius domesticus Arnold, 2005, and 1 Anaticola anseris (Linnaeus, 1758). These species are known from other geese and swans, but all of them were new to the swan goose. This result also indicates no overlap in lice species between older records and our findings from wild birds. Thus, ectoparasites collected from domestic or captive animals may provide biased information on the occurrence, prevalence, host selection, and host-ectoparasite interactions from those on wild hosts.     

Role of hepatic lipogenesis in the susceptibility to fatty liver in the goose (Anser anser)

In response to overfeeding, the Landes goose develops a fatty liver that is twice as large as that of the Poland goose, despite similar food intake. The role of hepatic lipogenesis in the genetic susceptibility to fatty liver was assessed in male overfed geese of the two breeds. For a similar hepatic protein content, total activities of malic enzyme, glucose-6-phosphate dehydrogenase, acetyl-Coa-carboxylase and fatty acid synthase, and specific activity and mRNA level of malic enzyme were about two-fold higher in the Landes goose. In the Poland goose, the weight of the fatty liver was correlated positively with the specific activity of ME and the VLDL concentration, which was not the case in the Landes breed. These results show that: (1) hepatic lipogenesis remains very active until the end of the overfeeding period; (2) the pentose-phosphate pathway may function in birds, contrary to what is assumed usually; (3) the level of hepatic lipogenesis is a major factor in the susceptibility to hepatic steatosis in different breeds of geese; and (4) ME activity may be a limiting factor of lipid synthesis in the less susceptible Poland breed.     

Spring ice formation on goose neck collars: effects on body condition and survival in Greenland white-fronted geese Anser albifrons flavirostris

During sub-zero temperatures and strong winds on 10–11 April 2013, we witnessed ice accumulation on plastic collars of staging Greenland white-fronted geese Anser albifrons flavirostris in Iceland. Ice affected 19 of 77 collared individuals seen, all of which had lost ice by 12 April, despite continuing freezing temperatures. Temperatures exceeded freezing after 14 April; daily observations found no recurrence of ice formation before geese left for Greenland in early May. Abdominal profile scores (a field assessment of accumulated body fat) did not differ significantly between geese with and without ice before departure from Iceland. There was no significant difference in return rates between geese with iced (79 %) or un-iced collars (83 %) reported the following autumn. These first reports of collar icing in over 30 years of the project give cause for concern and vigilance, but we recommend continued use of collars given exceptional weather conditions and lack of effects.     

Effects of Passive Social Support in Juvenile Greylag Geese (Anser anser): A Study from Fledging to Adulthood

In general, support by social allies may reduce stress, increase an individual's status and facilitate access to resources. In Greylag geese (Anser anser), offspring stay with their parents for an entire year or even longer and thereby enjoy social support in encounters with other flock members. We investigated the influence of spatial distance to one's allies on the outcome of agonistic encounters in a natural flock situation for a total of 12 sibling groups after fledging. In addition, we tested two groups of hand‐raised juvenile geese over a time span of 11/2 yr. Passive (i.e. not interfering) human supporters of different familiarity were placed at a standard distance during food provisionings, which produced a tight flock situation. Success in agonistic interactions increased with decreasing distance to members of their social unit. The hand‐raised juveniles were more successful in agonistic interactions and showed increased feeding rates when accompanied by a familiar human than when alone or with a non‐familiar human. The effect of the presence of familiar humans on success in agonistic encounters significantly decreased with increasing age, while feeding rates remained elevated. The positive effects of social support were particularly evident in females. We conclude that social support has similar effects and functions in the highly social greylag geese as reported for social mammals.     

Snow-patch foraging by pink-footed geese Anser brachyrhynchus in south Iceland

The pre-nesting feeding behaviour of pink-footed geese was studied in hayfields in southern Iceland during the late spring of 1989. Persistent snow-patches protected underlying grass from the effects of severe night-time frost. Areas within 1 m of snow-patches had significantly greater amounts of green material than those further away; green material contained more than double the protein of brown, dead material, which predominated in open fields. Geese spent nearly 60 times more time feeding within 1 m of snow patches than expected by chance, and 20 times more time within 2–5 m. Their feeding rates here were faster and their step rate slower than further away. In this way, the geese selected the prime forage as soon as it became available.     

Gene expression profile of estrogen receptor alpha and beta in the ovaries of Zi geese (Anser cygnoides)

The profile of ERalpha and ERbeta gene expression in the ovaries of Zi geese at 1 day and 1,2, 3, 4, 5 and 8 months of age (n=8, respectively) was examined by quantitative real-time PCR (qRT-PCR). The results showed that the expression of ERalpha and ERbeta mRNA was greater at 1 to 5 and 8 months compared with that observed at 1 day. In particular, the level of expression of ERalpha and ERbeta at 8 months was greater, 2.47 +/- 0.23 fold and 29.07 +/- 1.25 fold, respectively, compared with that at 1 day (P<0.05). The expression of ERalpha mRNA was not significantly different at 1, 2, 3 and 4 months (P>0.05). The level of expression of ERalpha mRNA at 5 months was 1.86 +/- 0.17 fold higher than at 1 day (P<0.05). The level of expression of ERbeta mRNA at 2, 3, 4, 5 and 8 months (1.96 +/- 0.13, 2.58 +/- 0.08, 2.08 +/- 0.05, 3.25 +/- 0.11 and 29.07 +/- 1.25 fold, respectively, P<0.05) was significantly higher than at 1 day. In summary, the expression of ERalpha and ERbeta mRNA in the ovaries of geese was increased between newborn and the laying stage. These results suggest that ERalpha and ERbeta mediate the process of ovarian development and egg laying in geese. In addition, ERbeta may play a more important role in regulating the response of the ovary to estrogen during the developmental and egg-laying stages.     

Using habitat selection theories to predict the spatiotemporal distribution of migratory birds during stopover – a case study of pink‐footed geese Anser brachyrhynchus

Understanding how animals select for habitat and foraging resources therein is a crucial component of basic and applied ecology. The selection process is typically influenced by a variety of environmental conditions including the spatial and temporal variation in the quantity and quality of food resources, predation or disturbance risks, and inter‐ and intraspecific competition. Indeed, some of the most commonly employed ecological theories used to describe how animals choose foraging sites are: nutrient intake maximisation, density‐dependent habitat selection, central‐place foraging, and predation risk effects. Even though these theories are not mutually exclusive, rarely are multiple theoretical models considered concomitantly to assess which theory, or combination thereof, best predicts observed changes in habitat selection over space and time. Here, we tested which of the above theories best‐predicted habitat selection of Svalbard‐breeding pink‐footed geese at their main spring migration stopover site in mid‐Norway by computing a series of resource selection functions (RSFs) and their predictive ability (k‐fold cross validation scores). At this stopover site geese fuel intensively as a preparation for breeding and further migration. We found that the predation risk model and a combination of the density‐dependent and central‐place foraging models best‐predicted habitat selection during stopover as geese selected for larger fields where predation risk is typically lower and selection for foraging sites changed as a function of both distance to the roost site (i.e. central‐place) and changes in local density. In contrast to many other studies, the nutritional value of the available food resources did not appear to be a major limiting factor as geese used different food resources proportional to their availability. Our study shows that in an agricultural landscape where nutritional value of food resources is homogeneously high and resource availability changes rapidly; foraging behaviour of geese is largely a tradeoff between fast refuelling and disturbance/predator avoidance.