Upland Goose Chloephaga Picta Research Articles

Habitat use by threatened sheldgeese (Chloephaga spp.) in Austral Patagonia at two spatial scales

Upland Goose Chloephaga picta, Ashy-headed Goose Chloephaga poliocephala and Ruddy-headed Goose Chloephaga rubidiceps are endemic goose-like threatened birds of southern South America. This work aimed to study how sheldgeese are distributed both temporally and spatially and characterize their habitat use in part of their breeding range in Southern Argentina, a little-explored subpolar region. We conducted nine surveys between spring 2013 and summer 2016 across a maximum of 235 km in Santa Cruz and 698 km in Tierra del Fuego per survey. We recorded the presence of non-breeding sheldgoose groups and Upland Goose pairs. We collected data at site-scale (~ 0.8 km2) and extracted data from geographic information systems for landscape-scale (5 km2) analyses. We recorded 2396 non-breeding groups containing one, two or the three species, 788 Upland Goose pairs and 102 solitary individuals. The Upland Goose was present in almost all groups and was the most abundant sheldgoose, followed by the Ashy-headed Goose. The Ruddy-headed Goose was observed only in 15 locations. Poa grasslands, meadows and Festuca grasslands were the habitats in which we detected most individuals. Sheldgoose density was higher in Tierra del Fuego than in Santa Cruz, and increased from spring to autumn and decreased in winter. The largest sheldgoose groups were concentrated in meadows and waterbodies. Sheldgeese selected sites with greater habitat diversity, habitat richness and number of habitats patches. Our results provide information to understand which environmental conditions favour sheldgeese and to aid in the selection of important areas for the conservation of these species.

Evaluating the impacts and benefits of sheldgeese on crop yields in the Pampas region of Argentina: A contribution for mitigating the conflicts with agriculture

Conflicts between waterfowl and agriculture are common in many nations around the world. However, these birds can also provide a variety of benefits that humanity can obtain from nature. There are three migratory and endemic sheldgeese (Ruddy-headed Goose Chloephaga rubidiceps, Ashy-headed Goose Chloephaga poliocephala and Upland Goose Chloephaga picta) which are species of conservation concern in Argentina. Sheldgeese are in constant conflict with the agricultural practices in the Pampas region of Argentina. The objective was to measure possible damages and benefits due to geese grazing on winter wheat crops during different growth stages, in the southeast of Buenos Aires province, Argentina. We established a stratified random plot design in nine fields, where we placed geese exclosure plots and plots without exclosure, allowing sheldgeese to graze. From May to September, we visited each field every two weeks. We performed transects where we counted and collected feces in order to estimate the grazing intensity. We analyzed the total concentration of Nitrogen (N) and Phosphorus (P) in the feces in the period before and after the wheat emergence. We also performed microhistogical analysis to evaluate sheldgeese diet in these two periods. During the crop growth and at harvest, we evaluated possible damages (wheat cover, percentage of eaten plants, percentage of eaten tillers, chlorophyll content, grain yield per plot, harvest index, weight of 1000 grains) and benefits (number of tillers per plant, percentage of weed cover, protein content) of geese grazing. We found that sheldgeese grazing varied along the different visits and among the experimental fields. Geese grazing negatively affected the wheat cover but there was no effect on the final yield. The input of nutrients provided by sheldgeese feces was higher in the period after the crop emergence, when they only ate wheat. Results on the birds’ diet showed that they fed on weeds before wheat emergence thus providing an ecosystem service. In this study, we found elements that could help to shed light on the real impact of sheldgeese in crops and discovered some benefits that these birds could be providing to crops in the Pampas ecoregion.

Niche Overlap Determination Through Habitat Suitability Models: A Management Tool for Native Birds of the Argentinean Pampas

In Argentina, predominantly in the Pampas ecoregion, the natural rangelands have increasingly been replaced by crops. Avifaunal studies have shown that the population density of several species decreased as the proportion of cropland in the landscape increased. The Greater Rhea Rhea americana and two migratory sheldgeese: the Upland Goose Chloephaga picta and Ashy-headed Goose Chloephaga poliocephala, are medium-large native species that have been common and sympatric inhabitants of the Pampas ecoregion. We aimed to analyse and compare the current ecological niches occupied by the three species during the non-breeding season in the southern Pampas of Argentina, the region where their original distributions overlapped, using Ecological Niche Factor Analysis. The three species showed high global marginality values, indicating that they occupied only a specific subset of environmental conditions of those available across the region. Suitable areas for Greater Rhea were located in the west and south of the study area, overlapping grazing lands and native habitats. The three species responded to landscape composition and configuration, as indicated by the low proportion of areas with suitable conditions for these medium-large birds. Suitable areas for Ashyheaded and Upland Geese were especially concentrated in the eastern part of the area and suitable areas for Upland Goose were more widespread than those suitable for the Ashy-headed Goose. We provide compelling evidence of low overlap between the ecological niches of the three species in the southern Pampas, which highlights the need for specific management strategies to ensure the conservation of these emblematic species. —Pedrana, J., Bernad, L., Maceira, N.O. & Isacch, J.P. (2018). Niche overlap determination through habitat suitability models: a management tool for native birds of the Argentinean Pampas. Ardeola, 65: 25–40.

Human–Sheldgeese conflict in agricultural landscapes: Effects of environmental and anthropogenic predictors on Sheldgeese distribution in the southern Pampa, Argentina

Sheldgeese species are currently the subject of serious conservation concern and have been a source of historical conflict with agricultural interests. Here we assess the relative effects of environmental and anthropogenic predictors on Sheldgeese (Ruddy-headed Goose Chloephaga rubidiceps, Ashy-headed Goose Chloephaga poliocephala and Upland Goose Chloephaga picta) distribution in the southern Pampas at different spatial scales. These birds were declared an “agriculture plage” by the government and this conflict with humans has been so far resolved with species persecution. We evaluate whether its current wintering distribution is shaped by anthropogenic disturbances or whether it can be better explained by differences in topography and preference for wetlands, or by landscape composition and configuration. We characterized the study region using 17 potential predictors related to environmental, human and landscape characteristics. We built habitat-suitability models to examine the relative effect of the variables on the regional occurrence of Sheldgeese. We performed vehicle surveys in southern Buenos Aires province, in two years (2011–2012), surveying 9200km of roads and recording 281 Sheldgeese flocks. Generalized additive models were used to model the presence/absence of Geese in 250-m cells. The habitat suitability models of Sheldgeese suggest that: (1) areas of low elevation surrounded by waterbodies are one of the main positive drivers of species distribution, (2) centers of human activity, which are regions with greater road accessibility, have a negative impact on species distribution, (3) heterogeneous landscape composed of croplands and grazing fields are preferred environments.

Primary productivity and anthropogenic disturbance as determinants of Upland Goose Chloephaga picta distribution in southern Patagonia

A species distribution may be determined by its responses to patterns of human distur-bance as well as by its habitat preferences. Here we investigate the distribution of theUpland Goose Chloephaga picta, which has been historically persecuted by farmers andranchers in Patagonia because it feeds on crops and pastures and is assumed to competewith sheep for forage. We assess whether its current breeding distribution is shaped bypersecution by ranchers or whether it can be better explained by differences in habitatprimary productivity and preference for wetlands, or by other anthropogenic distur-bances not associated with ranching. We built species distribution models to examine therelative effect of environmental and anthropogenic predictors on the regional distributionof Upland Goose. We performed vehicle surveys in the province of Santa Cruz, Argen-tina, in two years, surveying 8000 km of roads and recording 6492 Geese. Generalizedadditive models were used to model the presence⁄absence of Geese in 1-km cells. Themodels suggested that Upland Goose distribution is not currently affected by ranchercontrol, as the species is more abundant in areas with high sheep stocking levels, but it ispositively influenced by primary productivity and negatively influenced by urban areas.Anthropogenic disturbance caused by urban areas and oil extraction camps had a greaterimpact in limiting the species distribution than sheep ranching.Keywords: human disturbance, large-scale habitat models, primary productivity, semi-arid steppe,species distribution models, wildlife–livestock conflicts.Anthropogenic impacts are a major factor in deter-mining bird distributions and population trends(Newton 2004, Coombes et al. 2008, Moller2008). Disturbance can take many forms, forexample direct impacts such as habitat alteration,hunting or persecution (Brawn et al. 2001, Thiollay2006), and others of a more indirect nature, suchas additive reactions to human recreational activi-ties (Gill 2007, Kerbiriou et al. 2009). The currentgeographical ranges of many bird species mayreflect not only their habitat preferences but alsohuman disturbance (Caughley & Gunn 1996). Inareas long inhabited by humans, the original birdcommunities may have been trimmed, and therebyreduced to a subset of relatively tolerant species(Blumstein 2006, Devictor et al. 2007). However,the early effects of human disturbance on sensitivebirds could be best detected in protected or remote,recently or scarcely populated areas (Trainor 2007,Lees & Peres 2008).There is empirical evidence that many birdsavoid human disturbance and that their populationsizes can be negatively affected, but little is knownon the real magnitude of human disturbance atthe scale of a species distribution. To estimatethe effects of human disturbance it is necessaryto model the expected distribution of thespecies based on habitat preference, quality andavailability, and then estimate the effect of human

Female-specific colouration, carotenoids and reproductive investment in a dichromatic species, the upland goose Chloephaga picta leucoptera

Although studies on the evolution and function of female ornaments have become more numerous in the last years, the majority of these studies were carried out in cases where female ornaments were a smaller and duller version of the ornaments found in males. There are substantially fewer studies on species with female-specific ornaments. However, no study so far investigated the potential of female-specific colouration as a quality signal in birds with conventional sex roles. We studied female-specific ornamentation in a strongly sexually dichromatic species, the upland goose Chloephaga picta leucoptera, in two consecutive years. Male upland geese have white head and breast feathers and black legs, whereas females have reddish-brown head and breast feathers and conspicuous yellow-orange legs. We found that female-specific colouration in upland geese can reliably indicate different aspects of female phenotypic quality. Females with more orange coloured legs and more red-like head colours had higher clutch and egg volumes than females with a paler leg and head colouration, and a more reddish plumage colouration was related to a higher body condition. These relationships provide the theoretic possibility for males to assess female phenotypic quality on the basis of colouration. Furthermore, the females with a more orange-like tarsus colouration had higher plasma carotenoid levels. Both tarsus colouration and carotenoid concentrations of individual females were highly correlated across years, indicating that tarsus colour is a stable signal. Despite this correlation, small individual differences in plasma carotenoid concentrations between the two study years were related to differences in tarsus colouration. We thus show for the first time in a wild bird and under natural conditions that carotenoid-based integument colouration remains consistent between individuals in consecutive years and is also a dynamic trait reflecting individual changes in carotenoid levels. In this species, where pairs form life-long bonds, the honesty of the carotenoid-based integument colouration suggests that it may be a sexually selected female ornament that has evolved through male mate choice.Electronic supplementary materialThe online version of this article (doi:10.1007/s00265-010-0990-4) contains supplementary material, which is available to authorized users.

Seasonal clutch size decline and individual variation in the timing of breeding are related to female body condition in a non-migratory species, the Upland Goose Chloephaga picta leucoptera

Several studies have shown that waterfowl females in good condition lay larger clutches and start egg-laying earlier in a breeding season. However, most of these studies lack corresponding data on individual condition and timing of breeding in different years. We analysed data on clutch size, egg size, hatching date and female body condition of a non-migratory species, the Upland Goose Chloephaga picta leucoptera, recorded in three seasons on New Island, Falkand Islands. We found a strong seasonal decline in both egg and clutch size. Egg size increased with clutch size. The mean egg volume and total clutch volume increased with female body condition and hatching date was earlier for females in higher body condition. Chicks hatched from nests with higher mean egg volume had higher early body condition. We also compared individual females between different study years and found that individual body condition showed a significant repeatability between years, whereas hatching date did not. While female aging did not systematically affect hatching date, females produced clutches that hatched earlier in years of higher body condition. We could thus show for the first time that the frequently reported negative relationship between female condition and hatching date also holds true on an individual basis. To our knowledge, this is the first study on seasonal clutch size decline in sheldgeese and one of a few in waterfowl comparing condition and timing of breeding within individuals between different years.

Non-invasive measurement of faecal glucocorticoid metabolites in Upland Geese Chloephaga picta

Glucocorticoid (GC) hormones rise in response to stressors, including natural events including weather or predator presence, and human activities, such as hunting, scientific research or recreational visits. However, because blood sampling itself causes stress and is dangerous or even impossible in some wildlife species, feedback-free methods for GC determination are needed to assess stress in these animals. Faecal GC analyses have thus gained interest. Here, we validate a non-invasive method to estimate the physiological stress in the Upland goose Chloephaga picta. An adrenocorticotropin hormone (ACTH) challenge was conducted in captive adults (female and male), and droppings were collected before, during and after the experiment. Corticosterone metabolite (CM) secretion in response to the ACTH challenge was measured with several enzyme immunoassays (EIA) to find the most appropriate test. We used CM levels during the periods before and after the experiment as control data. An EIA for 11-oxoetiocholanolone achieved the highest response to the ACTH challenge and also reflected a stress response to unfamiliar environment. Furthermore, CM concentrations of dry samples were highly correlated with the corresponding non-dried (frozen) samples. The data suggest that this method is appropriate to measure the stress in Upland geese, and that samples can be stored either frozen or dry form.