Winter Home Research Articles

Lifestyle and satisfaction of winter migrants

A large number of seniors migrate to southern, warm climates during the winter, providing a substantial boost to the winter destination's economy. This study of 1443 wintering migrants was designed to provide much needed information about what lifestyle factors and risks are important to the migrants and how satisfied they are with the factors both in their winter homes and in their permanent homes. Effects of gender, age and education level on the lifestyle and risk factors are also identified. Findings should help destination managers to better understand the winter migrants' lifestyle and risk preferences to better attract and retain them.

Winter home range and habitat use by porcupines in Alaska

AbstractHabitat selection results from trade‐offs between availability and use of resources under constraints of predation, competition, or other threats, which can vary spatially and temporally. For northern herbivores, winter food availability and quality can limit population size and may drive habitat preference. North American porcupines (Erethizon dorsatum) are widespread generalist herbivores that range from Mexico to the northern reaches of Alaska. During the long Alaskan winter, porcupines deal with high energetic demands resulting from low ambient temperatures while subsisting on low quality forage. We tracked free‐ranging porcupines over 3 winters in southcentral Alaska to determine habitat selection and home range size in relation to diet. Porcupines maintained larger than expected home ranges, and selected for conifer‐hardwood forests at the home range level. Individual variation among porcupines was too large to determine a pattern of microhabitat selection among trees. Regardless, direct observations revealed that porcupines used only white spruce and paper birch trees for foraging. White spruce may provide some nutritional and thermoregulatory advantage over paper birch; however, porcupines did feed on paper birch cambium, suggesting some nutritional requirement is met by eating paper birch. Porcupines most likely feed on paper birch cambium when detoxification pathways used to process plant toxins in white spruce needles are saturated. Maintaining mixed conifer‐hardwood forests in southcentral Alaska would provide suitable winter habitat for porcupines and may alleviate damage to single species stands of conifers or hardwoods that are preferred by commercial forestry operations. © 2012 The Wildlife Society.

Linking habitat heterogeneity to space use by large herbivores at multiple scales: From habitat mosaics to forest canopy openings

Although habitat selection and home range size of herbivores in forested landscapes are generally related to the composition and spatial arrangement of open and forested habitat categories, it is unclear how herbivores respond to finer habitat mosaics such as more productive canopy openings within forest stands. We aimed to determine the relationships between habitat selection and home range size of 32 white-tailed deer (Odocoileus virginianus) females and spatial heterogeneity in forage and cover at multiple scales. We used GPS telemetry to delineate summer and winter home ranges and to evaluate habitat selection. We used landscape metrics to measure spatial heterogeneity of open and closed habitat categories within each home range and in three circles of radii of 1000, 2000 and 3000m centered on each home range, and field surveys to quantify spatial patterns in canopy openings within forest stands. Deer responded to forage abundance at multiple scales during summer, as they selected peatlands within the landscape, canopy openings within forest stands, and reduced the size of their home range with increasing forbs and deciduous shrubs cover. Deer also responded to forage abundance during winter as they selected areas with high proportions of food-rich balsam fir stands to establish their home range and had a smaller home range size when the density of food sources increased. However, in areas where the proportion of food-rich balsam fir stands was less available, deer selected heterogeneous habitat mosaics to settle their winter home range. Moreover, deer responded positively to edge density of cutblocks only during winter and they did not select canopy openings during that season. Winter forage such as windblown fir trees were highly associated to edges between clear-cuts and balsam fir stands making these large openings an important element of deer winter habitat in ecosystem modified by long-term browsing. Our results emphasize the significance of considering multiple and nested mosaics of openings and continuous cover when assessing habitat selection patterns and home range size of herbivores living in forested landscapes, as the influence of spatial heterogeneity in resources varied with the constraints of seasonal environments.

Seasonal Migration of Sika Deer in the Oku-Chichibu Mountains, Central Japan

Abstract. Movements and seasonal home ranges of 6 GPS collared sika deer were investigated at the Oku-Chichibu Mountains, central Honshu, from April 2009 to March 2010. All deer migrated between discrete summer and winter home ranges. The linear migration distance ranged from 2.5 to 31.9 km. Mean elevation during the summer and the winter ranged from 980 to 1,782 m, and from 1,204 to 1,723 m, respectively. Two deer were upward migrants and 4 deer were downward migrants. Taking into consideration of the relatively small snow accumulation in the summer home range, the possibility of autumn migration to avoid deep snow is low. The percentage of steep slope in the winter home range was higher than that in the summer. Bamboo grass was not found in the summer home range, but was predominant in the winter home range. Road density decreased in the winter home range compared to the summer. Only 2 out of 6 deer stayed mainly in the wildlife protection area during the winter. Our results indicate that the autumn mig...

Linking alternative food sources to winter habitat selection of herbivores in overbrowsed landscapes

AbstractDuring winter, ungulates in boreal forests must cope with high energetic costs related to locomotion in deep snow and reduced forage abundance and quality. At high density, ungulates face additional constraints, because heavy browsing reduces availability of woody browse, the main source of forage during winter. Under these severe conditions, large herbivores might forage on alternative food sources likely independent of browsing pressure, such as litterfall or windblown trees. We investigated the influence of alternative food sources on winter habitat selection, by studying female white‐tailed deer (Odocoileus virginianus) living in 2 landscapes with contrasted browse abundance, recently logged and regenerated landscapes, in a population at high density and on a large island free of predators. We fitted 21 female white‐tailed deer with Global Positioning System (GPS) collars and delineated winter home ranges and core areas. We measured snow conditions in different habitat categories and sampled vegetation in the core areas and in the rest of the home ranges to determine how forage abundance, protective cover, and snow conditions influenced habitat selection within the home range. In both landscapes, deer were less likely to use open habitat categories as snow accumulated on the ground. At a finer scale, deer inhabiting the regenerated landscape intensively used areas where balsam fir cover was intermediate with greater balsam fir browse density than in the rest of the home range. In the recently logged landscape, deer were more likely to be found near edges between clear‐cuts and balsam fir stands and in areas where windblown balsam fir trees were present; the latter being the most influential variable. Although balsam fir browse was sparse and mainly out of reach in this landscape, deer increased the use of areas where it was present. Our results offer novel insights into the resource selection processes of northern ungulates, as we showed that access to winter forage, such as woody browse and alternative food sources, depends on climatic conditions and stochastic events, such as abundant compacted snow or windthrows. To compensate for these scarce and unpredictable food supplies, deer selected habitat categories, but mostly areas within those habitat categories, where the likelihood of finding browse, litterfall, and windblown trees was greatest. © 2011 The Wildlife Society.

Discharge during Winter Does Not Increase Duration of Oxygen Therapy in Preterm Babies with Chronic Lung Disease (CLD)

Background: Preterm babies with significant CLD may require home oxygen after hospital discharge. Due to the risk of winter viral ilnesses we hypothesised that CLD babies discharged home during winter would require oxygen therapy for longer after discharge. Methodology: We reviewed our database of babies with CLD discharged home on oxygen between 1/1/2007 and 31/12/2010. We compared the age at discharge and duration of home oxygen between babies discharged in summer (April - September) with those in winter (October - March). All babies were managed by the Neonatal Outreach Team and oxygen was weaned according to established unit protocols. Results: During the study period a total of 74 babies (38 male, 36 female) were discharged home who weaned off oxygen therapy. Mean (±SD) birthweight was 967±260g and gestation 27.3±2 weeks. The babies were discharged at a mean gestation of 38.7±4.6 weeks and discontinued oxygen at a gestation of 47.7±13.2 weeks. n=31 babies were discharged over winter and n=43 in summer. There were no differences in birthweight and gestation between the two cohorts. Discharge gestation and corrected gestation at discontinuation of oxygen did not differ between the groups. There were no correlations between duration of oxygen therapy and month of discharge or gender. Conclusion: Home oxygen babies discharged home in winter did not have an increase in hospital length of stay and did not require oxygen for a longer. In contrast to our hypothesis the duration of home oxygen therapy in CLD babies was not affected by the season of discharge.

Home on the range: spatial ecology of loggerhead turtles in Atlantic waters of the USA

AbstractAim Although satellite tracking has yielded much information regarding the migrations and habitat use of threatened marine species, relatively little has been published about the environmental niche for loggerhead sea turtles Caretta caretta in north‐west Atlantic waters.Location North Carolina, South Carolina and Georgia, USA.Methods We tracked 68 adult female turtles between 1998 and 2008, one of the largest sample sizes to date, for 372.2 ± 210.4 days (mean ± SD).Results We identified two strategies: (1) ‘seasonal’ migrations between summer and winter coastal areas (n = 47), although some turtles made oceanic excursions (n = 4) and (2) occupation of more southerly ‘year‐round’ ranges (n = 18). Seasonal turtles occupied summer home ranges of 645.1 km2 (median, n = 42; using α‐hulls) predominantly north of 35 ° latitude and winter home ranges of 339.0 km2 (n = 24) in a relatively small area on the narrow shelf off North Carolina. We tracked some of these turtles through successive summer (n = 8) and winter (n = 3) seasons, showing inter‐annual home range repeatability to within 14.5 km of summer areas and 10.3 km of winter areas. For year‐round turtles, home ranges were 1889.9 km2. Turtles should be tracked for at least 80 days to reliably estimate the home range size in seasonal habitats. The equivalent minimum duration for ‘year‐round’ turtles is more complex to derive. We define an environmental envelope of the distribution of North American loggerhead turtles: warm waters (between 18.2 and 29.2 °C) on the coastal shelf (in depths of 3.0–89.0 m).Main conclusions Our findings show that adult female loggerhead turtles show predictable, repeatable home range behaviour and do not generally leave waters of the USA, nor the continental shelf (< 200m depth). These data offer insights for future marine management, particularly if they were combined with those from the other management units in the USA.

Molting, Staging, and Wintering Locations of Common Eiders Breeding in the Gyrfalcon Archipelago, Ungava Bay

The northern common eider (Somateria mollissima borealis) has become a source of concern because of recent declines and possible overharvest. Birds that breed in the Canadian mid-Arctic winter in both Greenland and Canada, but the wintering grounds of birds that breed farther south are unknown. Our objectives were thus to identify the molting and wintering areas of birds breeding in Ungava Bay and to compare their home-range sizes during the pre-molt, molt, post-molt, and winter periods. Using satellite telemetry, we determined that common eiders breeding in the lower Arctic winter in Greenland (67%) and Canada (33%). These proportions are consistent with the split established for common eiders that breed farther north. Females spent their pre-molt period close to their breeding islands and had the smallest home ranges during the molt period. Winter home ranges were larger in Canada than in Greenland, probably because they contained more ice. Once settled, birds wintered in a relatively small area and did not undertake long movements. Distance between molt and winter sites ranged between 1054 and 2173 km. Duration of migration to or from wintering areas varied among individuals from rapid movement in a few days to slow progress over a month. Fall migration occurred in late October or early November, and spring migration, in early to mid-May. This study highlights the importance of Ungava Bay for northern common eiders and the need for international collaboration to ensure sustainable use of the resource.

The Food Preference Paradigm: A Review of Autumn–Winter Food Use by North American Dabbling Ducks (1900–2009)

Abstract Studies describing food use (i.e., diet) of nonbreeding dabbling ducks Anas spp. are essential to understanding physiological needs of and recommending habitat management for these birds. We conducted a review of published autumn and winter food-use studies of dabbling ducks in North America to characterize the current state of knowledge and identify remaining research needs. We initiated our review to determine whether valuations of duck foods and the term “preference” commonly used by researchers and in waterfowl management guides (i.e., the food preference paradigm) were supported by available peer-reviewed literature. We analyzed peer-reviewed literature (1900–2009) on autumn–winter food use of dabbling ducks (n = 59 studies). Most studies (68%) used methods known to contain substantial bias including data from gizzards and hunter-collected ducks. Only 5% of published articles reliably determined food selection by concurrently measuring food use and availability, and no study determined food use at a scale appropriate for winter home ranges of dabbling ducks. In some habitats commonly managed for waterfowl (e.g., agricultural lands), few if any collections of ducks are available to obtain data on food use. The limited geographic and habitat scope of unbiased food use and selection studies for dabbling ducks during autumn and winter suggests that the food-preference paradigm found in waterfowl management literature is not supported by empirical evidence and that managers must continue to use best judgment in managing foraging habitats for waterfowl. Researchers and conservation planners should aim to reduce uncertainty regarding the value of waterfowl foods by conducting contemporary food-selection studies using unbiased collection and processing methodologies. Further, we suggest future researchers conduct concurrent behavioral observations, habitat use, and food selection studies within winter home ranges of dabbling ducks to aid managers in meeting the nutritional requirements of dabbling ducks during autumn and winter in North America.

The Home Environment of Japanese Female University Students - Association with Respiratory Health and Allergy

A study was undertaken to determine the association between the home environment along with the respiratory and allergy symptoms reported among female university students in Japan (N =153). A multiple logistic regression was applied for the determination and the study was controlled based on the age of the students, whether the student smokes and history of asthma/allergy suffering in parents. The characteristics of the population were: 15.7% are diagnosed asthma, 56.9% suffered pollen allergy, 15.7% cat allergy, 11.1% dog allergy, 25.0% wheeze in breathing, 24.2% suffered daytime breathlessness and 9.3% suffered nocturnal attacks of breathlessness. Evaluated characteristics were: 41.2% had a pet at home, 21.6% environmental tobacco smoke (ETS), 20.9% current dampness or moulds, 6.6% recent indoor painting, 7.2% new floor material, and 56.2% window condensation at home in winter. Wheeze was more common in concrete houses (OR = 3.33; p<0.05) and homes with water leakage and moulds infestation in the last 5 years (OR = 3.75; p<0.05), window condensation (OR=2.93; p<0.05) and ETS (OR=3.04; p<0.05). Nocturnal breathlessness was related to current building dampness (OR = 7.48; p<0.05), in particular to floor dampness. Furry pet allergy was more common in newer ( p<0.05) and newly painted homes (OR = 6.59; p<0.05). Airway infections were more common in homes with new floor material (OR=4.19; p<0.05). In conclusion, asthma, airway infections and allergies were common among female university students and related to home environmental exposures.

Keeping Warm: Social Connectedness and Technology - A Case Study of Rotherham, England ‘Technology and Health in the Elderly’

AbstractThe purpose of this paper is to discuss the relationship between social connectedness and modern technology with the ability of older people to keep warm during winter. Findings from previous research in England found that high fuel prices, low income and changing patterns of fuel consumption are key barriers to keeping warm in winter for many families. Living in a cold home increases the risk of winter hospital admissions, especially among the elderly with respiratory problems. This multi disciplinary interview-based project conducted in Rotherham (England) involved social care professionals, public health specialists, and user–representatives, sociologists and medical anthropologists. We have identified many ways in which modern technology is a barrier in heating homes in winter. Using the sociological theory of Symbolic Interaction (SI) we will discuss how social connectedness and use of modern technology influences older people in heating their homes and ultimately how these factors affect their health and well being. This paper is aimed at social care professionals, policy makers, public health specialists and governments.

Factors influencing winter home ranges and activity patterns of raccoon dogs Nyctereutes procyonoides in a high-altitude area of Japan

Between October 2006 and June 2007, we radio-tracked six adult raccoon dogs Nyctereutes procyonoides (Gray, 1834) in a high-altitude area of Japan to determine which factors influenced home ranges, daily movements, and activity patterns of Japanese raccoon dogs, with an emphasis on the winter season. The home-range sizes for the six individuals were smaller in winter than in autumn. In winter, the daily movement distances significantly decreased in response to decreasing temperature and increasing snow depth, suggesting these environmental factors contributed to a decrease in the home-range sizes during this period. Moreover, during daytime, raccoon dogs were more active in winter than in the snow-free periods (autumn and spring), and the proportion of the daytime movement distances to the total daily movement distances significantly increased as the mean daily air temperatures decreased. Therefore, it appears that the raccoon dogs in our study area passed the winter by minimizing their energy expenditure by restricting their movements when temperatures were at their lowest and snow depth was highest, and by moving more during the daytime when temperatures were higher.

Wintering Behavior, Physiology and Site Fidelity in a Partial Migrant, the American Dipper (Cinclus mexicanus)

Foraging behavior, physiological state and site fidelity of resident (sedentary) and migratory American Dippers (Cinclus mexicanus) were compared to assess whether differences in over-wintering behavior or physiology explain the lower annual survival rate of resident individuals. Residents spent more time resting (23 vs. 14% of the time) and less time foraging (71 vs. 81% of the time) than migrants. However, there were no detectable differences in energetic intake (kJ/hr), foraging success (kJ/hr spent foraging), or physiological state (measured as size-corrected mass, hematocrit, leucocrit, total white blood cell count, and heterophil to lymphocyte ratio; immunoglobulin, triglyceride, and free glycerol levels; and total antioxidant capacity and total oxidative status of plasma). Foraging success, size-corrected mass and plasma triglyceride levels increased with date for both migrants and residents, indicating that both groups built up fat reserves as winter progressed. Resident individuals exhibited higher winter site fidelity than migrants (sighted on the same section of the river on 70 vs. 53% of weekly censuses). The lower site fidelity and, hence, greater movement of migrants may increase survival by allowing them to seek more suitable microhabitats during adverse conditions. Further work on the relationship between mortality rates, movement and winter home range size of migrant and resident dippers is needed to test the latter hypothesis.

Source apportionment of indoor residential fine particulate matter using land use regression and constrained factor analysis

Source contributions to urban fine particulate matter (PM(2.5) ) have been modelled using land use regression (LUR) and factor analysis (FA). However, people spend more time indoors, where these methods are less explored. We collected 3-4- day samples of nitrogen dioxide and PM(2.5) inside and outside of 43 homes in summer and winter, 2003-2005, in and around Boston, Massachusetts. Particle filters were analysed for black carbon and trace element concentrations using reflectometry, X-ray fluorescence (XRF), and high-resolution inductively coupled mass spectrometry (ICP-MS). We regressed indoor against outdoor concentrations modified by ventilation, isolating the indoor-attributable fraction, and then applied constrained FA to identify source factors in indoor concentrations and residuals. Finally, we developed LUR predictive models using GIS-based outdoor source indicators and questionnaire data on indoor sources. FA using concentrations and residuals reasonably separated outdoor (long-range transport/meteorology, fuel oil/diesel, road dust) from indoor sources (combustion, smoking, cleaning). Multivariate LUR regression models for factors from concentrations and indoor residuals showed limited predictive power, but corroborated some indoor and outdoor factor interpretations. Our approach to validating source interpretations using LUR methods provides direction for studies characterizing indoor and outdoor source contributions to indoor cocentrations. By merging indoor-outdoor modeling, factor analysis, and LUR-style predictive regression modeling, we have added to previous source apportionment studies by attempting to corroborate factor interpretations. Our methods and results support the possibility that indoor exposures may be modeled for epidemiologic studies, provided adequate sample size and variability to identify indoor and outdoor source contributions. Using these techniques, epidemiologic studies can more clearly examine exposures to indoor sources and indoor penetration of source-specific components, reduce exposure misclassification, and improve the characterization of the relationship between particle constituents and health effects.

Predictors of indoor air concentrations in smoking and non-smoking residences.

Indoor concentrations of air pollutants (benzene, toluene, formaldehyde, acetaldehyde, acrolein, nitrogen dioxide, particulate matter, elemental carbon and ozone) were measured in residences in Regina, Saskatchewan, Canada. Data were collected in 106 homes in winter and 111 homes in summer of 2007, with 71 homes participating in both seasons. In addition, data for relative humidity, temperature, air exchange rates, housing characteristics and occupants’ activities during sampling were collected. Multiple linear regression analysis was used to construct season-specific models for the air pollutants. Where smoking was a major contributor to indoor concentrations, separate models were constructed for all homes and for those homes with no cigarette smoke exposure. The housing characteristics and occupants’ activities investigated in this study explained between 11% and 53% of the variability in indoor air pollutant concentrations, with ventilation, age of home and attached garage being important predictors for many pollutants.

Solving mould and condensation problems: A dehumidifier trial in a suburban house in Britain

High humidity can lead to condensation and mould formation if a house is well sealed and indoor temperatures fall significantly during the night. Solutions that have been offered are to keep heaters on throughout the night, to increase the thickness of insulation, or to install heat-exchange ventilators. These solutions are expensive. The cultural practice of heating homes to around 20 °C during the day and evening has been challenged, but lack of heating will not prevent natural temperature swings. A more direct solution is to remove the moisture from the air using a dehumidifier. This study reports a controlled 28-night trial of a dehumidifier in a suburban UK home in winter. The machine drew an average of 680 ml of water out of the air each night and consumed around 1 kW of electrical energy per night, with a high correlation between volume of water collected and energy consumed. Occupants reported that the previously severe condensation problem was solved, and measurements showed that the latent heat of the collected moisture also increased the ambient temperature. The estimated cost of running the machine for half the nights of the year is €28, an order of magnitude cheaper than other solutions.

Will drivers for home energy efficiency harm occupant health?

The U.K. government has committed to an 80% reduction in carbon emissions by 2050, with housing accounting for 27% of total current emissions. There are several drivers both to reduce emissions from homes and to reduce fuel poverty, promoting a range of building and behavioural measures in homes. The health benefits of warmer homes in winter have been described, but there has been less consideration of the potential negative impacts of some of these measures. We examine the changes in U.K. homes, and the possible consequences for health. The main concerns for health surround the potential for poor indoor air quality if ventilation is insufficient and the possible risks of overheating in heatwave conditions. This paper notes a limited evidence base and the need for further research on the health effects of energy-efficient homes, particularly with regard to ventilation.

Patterns of space and habitat use by northern bobwhites in South Florida, USA

The manner by which animals use space and select resources can have important management consequences. We studied patterns of habitat selection by northern bobwhites (Colinus virginianus) on Babcock-Webb Wildlife Manage- ment Area, Charlotte County, Florida and evaluated factors influencing the sizes of their home ranges. A total of 1,245 radio-tagged bobwhites were monitored for 19,467 radio days during 2002-2007. The mean (±1 SE) annual home range size, estimated using the Kernel density method, was 88.43 (±6.16) ha and did not differ between genders. Winter home ranges of bobwhites (69.27±4.92 ha) were generally larger than summer home ranges (53.90±4.93 ha). Annual and winter home ranges were smaller for bobwhites whose ranges contained food plots compared to those that did not; however, the presence of food plots did not influence summer home ranges. We used distance-based methods to investigate habitat selection by bobwhites at two scales: selection of home ranges within the study site (second-order selection) and selection of habitats within home ranges (third-order selection). Acrossboth scales, bobwhitesgenerally preferred food plots and dry prairie habitat and avoided wet prairies and roads. This pattern was generally consistent between genders and across years. Our data indicate that management practices aimed at increasing and maintaining a matrix of food plots and dry prairie habitat would provide the most favorable environment for bobwhites.

Alternative Strategies of Space use of Female Red Deer in a Mountainous Habitat

Alternative strategies of space use may be present in a species or in a population as a response to different environmental parameters, especially in mountainous habitats, where heavy snowfalls in winter may determine important variations of habitat quality. The spatial behaviour of 20 radiotagged red deer hinds was assessed in a mountainous habitat in the eastern Italian Alps from 2002 to 2004. Two groups of hinds were identified: ‘resident’ females remained in the same area throughout the year; ‘shifter’ females showed separated winter and summer areas. No significant difference was found in seasonal home-range sizes between resident and shifter hinds in 2002 and in 2003. Each year, in summer, home-range quality of shifter hinds was significantly better than that of resident ones, while, in winter home ranges, habitat diversity was similar in the two groups. During the severe winter 2003–2004, 33% of females summering in lower quality habitat died, whereas mild winters did not influence the survival of our collared hinds.

No Other River

It's an annual rite. Sometime between late February and early April, I drive west on Interstate 80. In south-central Nebraska, both the Platte River and the interstate swing low toward the Nebraska-Kansas state line. Somewhere along the bottom of this catenary curve, I pull off the interstate and drive gravel roads south of the river. What I'm looking for is the world's largest gathering of migrating sandhill cranes. They're easy to find. The half-million cranes are concentrated, more or less, within the forty-mile stretch of the river between Grand Island and Kearney, the narrow waist on the hourglass-shaped Central Flyway and the narrowest part of the crane's migratory route. Because this part of Nebraska is relatively flat and open, one doesn't have to look hard or far to see the elegant, leggy, four-foot tall, red-capped, gray birds. I come to watch them feast and dance and drop out of and rise into the sky. Most of the cranes congregating on the Platte are lesser sandhills, the crane with the longest migration. The remaining cranes are greater sandhills and the endangered whooping cranes. After the roughly 600-mile trip from their winter homes in eastern New Mexico, northwestern Texas, and northern Mexico, the sandhill cranes are lean and hungry. Once in Nebraska, they glean corn left from the harvest and slurp up snails, worms, grubs, insects, snakes, and crayfish in the wet meadows near the Platte. Each crane stays in Nebraska about four weeks and adds a pound or so of fat during this time. At night, they return to the shallow river where they sleep standing in water, usually on one leg in roosts of as many as 10,000 to 15,000 cranes per half mile of river. From the air, these sleeping masses, some of which are a mile long, look sandbar-shaped, and the individual cranes are evenly spaced, as if, writes Steve Grooms in The Cry of the Sandhill Crane, positioned on a grid of four-foot squares, each bird staying just beyond the reach of its neighbors' sharp bills. At dawn, the cranes head for the fields near the river. And there, they dance, bowing, strutting, pumping their heads, raising their bills, flapping their wings, tossing corncobs into the air, and gracefully hopping as high as twenty feet. Great bouncing