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546 records · Page 31Linked to original sources
USGS2021

Red-footed Falcon Falco vespertinus

Red-footed falcons (Falco vespertinus) are a small, long-distance and obligate migrant falcon that breeds at the forest-steppe interface in Eurasia and winters in Southern Africa. Research carried out with geolocators and satellite transmitters show that during the southbound migration Central Asian birds migrate through the Caucasus and the Middle East, while those from Eastern Europe cross the Eastern Mediterranean. Once in Africa, they cross the Sahara, the Sahel, where they perform short stopovers, and the Congo rainforest or the Rift valley, heading towards the wintering grounds. Northbound migration involves stopovers in West Africa and long crossings over the Mediterranean Sea. Both visual observations and tracking studies show that at least some populations of the species perform a clockwise loop migration that involves extensive longitudinal movements and. for some sub-populations, crossing the Central Mediterranean only during spring. Pre-breeding migration has a longer duration than post-breeding migration, probably because stopovers are longer and wind assistance lower. Red-footed falcons also face substantial anthropogenic threats along migration, particularly the risk of shooting at migratory bottlenecks.

Book chapter↗
USGS2022

Whooping crane stay length in relation to stopover site characteristics

Whooping crane ( Grus americana ) migratory stopovers can vary in length from hours to more than a month. Stopover sites provide food resources and safety essential for the completion of migration. Factors such as weather, climate, demographics of migrating groups, and physiological condition of migrants influence migratory movements of cranes (Gruidae) to varying degrees. However, little research has examined the relationship between habitat characteristics and stopover stay length in cranes. Site quality may relate to stay length with longer stays that allow individuals to improve body condition, or with shorter stays because of increased foraging efficiency. We examined this question using habitat data collected at 605 use locations from 449 stopover sites throughout the United States Great Plains visited by 58 whooping cranes from the Aransas–Wood Buffalo Population tracked with platform transmitting terminals. Research staff compiled land cover (e.g., hectares of corn; landscape level) and habitat metric (e.g., maximum water depth; site level) data for day use and evening roost locations via site visits and geospatial mapping. We used Random Forest regression analyses to estimate importance of covariates for predicting stopover stay length. Site-level variables explained 9% of variation in stay length, whereas landscape-level variables explained 43%. Stay length increased with latitude and the proportion of land cover as open-water slough with emergent vegetation as well as alfalfa, whereas stay length decreased as open-water lacustrine wetland land cover increased. At the site-level, stopover duration increased with wetted width at riverine sites but decreased with wetted width at palustrine and lacustrine wetland sites. Stopover duration increased with mean distance to visual obstruction as well as where management had reduced the height of vegetation through natural (e.g., grazing) or mechanical (e.g., harvesting) means and decreased with maximum water depth. Our results suggest that stopover length increases with the availability of preferred land cover types for foraging. High quality stopover sites with abundant forage resources may help whooping cranes maintain fat reserves important to their annual life cycle.

Proceedings of the North American Crane Workshop↗
USGS1995

Migratory bird population changes in North Dakota

The status of migratory bird populations in North America has received increased attention in recent years. Much of this consideration has been on Neotropical migrants, especially those associated with eastern forests. The status of migratory bird populations in the Great Plains has received far less attention. During the past quarter-century, populations of many species of birds that breed in the northern Great Plains have increased or declined, as indicated by trends from the North American Breeding Bird Survey. In 1967 Stewart and Kantrud (1972) conducted a survey of breeding bird populations throughout North Dakota. This study offered a rare glimpse of bird populations breeding in the northern Great Plains as well as important baseline data on breeding bird populations. These data help us evaluate relationships between birds and habitat conditions. We repeated the survey to compare bird populations in North Dakota during 1967 with those in 1992 and 1993.

North Dakota↗
USGS1998

Wetland birds in the northern Great Plains

When the Wisconsin glacier retreated about 10,000 years ago, it left innumerable depressions scattered throughout the northern Great Plains. These depressional wetlands, called prairie potholes, contain water for various lengths of time in most years (Kantrud et al. 1989). Their size, permanence, hydrology, water chemistry, plant associations, and invertebrate communities vary widely among wetlands and, within a basin, through time (Cowardin et al. 1979). These diverse wetlands support a breeding avifauna as rich and varied as the wetlands themselves. Johnsgard (1979) listed 72 breeding bird species associated with freshwater pond environments in the Great Plains. Other species, such as the northern harrier, marbled godwit, Le Conte’s sparrow, and Nelson’s sharp-tailed sparrow, are associated with grasslands but extensively use these prairie wetlands. Stewart (1975) identified 63 breeding bird species as wetland associates in North Dakota alone. Since 1975, several species could be added to Stewart’s list (Faanes and Stewart 1982), including the reintroduced Canada goose (Lee et al. 1989) and several herons, egrets, and ibises that have expanded their breeding range into the state (Lokemoen 1979). Most wetland birds are short-distance migrants, wintering primarily north of the United States–Mexico border (Igl and Johnson 1995).

Book chapter↗
USGS1999

Biogeographical profiles of shorebird migration in midcontinental North America

The biogeographic information described here will help identify the uniqueness of different regions of the plains to migrating shorebirds. Although shorebirds migrating along Atlantic and Pacific coastal areas are capable of long jumps between refueling stops, there is evidence that some species move short rather than long distances between refueling sites. Maps of distribution patterns and chronology accounts can lend insight towards understanding migration strategies of the different shorebird species. This report focuses on the distribution patterns of enroute migrants that refuel in interior wetlands during migration. We provide information on the spatial and temporal occurrence and habitat requirements for individual species and groups of species with the intent that this information be used in guiding management efforts.

Alberta, Saskatchewan, Manitoba, Montana, Wyoming,↗