Sandhill Crane Roost Selection, Human Disturbance, and Forage Resources

Sites used for roosting represent a key habitat requirement for many species of birds because availability and quality of roost sites can influence individual fitness. Birds select roost sites based on numerous factors, requirements, and motivations, and selection of roosts can be dynamic in time and space because of various ecological and environmental influences. For sandhill cranes (Antigone canadensis) at their main spring staging area along the Platte River in south-central Nebraska, USA, past investigations of roosting cranes focuse donphysical channel characteristics related to perceived security as motivating roost distribution.We used 6,310 roost sites selected by 313 sandhill cranes over 5 spring migration seasons (2003–2007) to quantify resource selection functions of roost sites on the central Platte River using a discrete choice analysis. Sandhill cranes generally showed stronger selection for wider channels with shorter bank vegetation situated farther from potential human disturbance features such as roads, bridges, and dwellings.Furthermore, selection for roost sites with preferable physical characteristics (wide channels with short bank vegetation) was more resilient to nearby disturbance features than more narrow channels with taller bank vegetation. The amount of cornfields surrounding sandhill crane roost sites positively influenced relative probability of use but only for more narrow channels \u3c100m and those with shorter bank vegetation. We confirmed key resource features that sandhill cranes selected at river channels along the Platte River, and after incorporating spatial variation due to human disturbance, our understanding of roost site selection was more robust, providing insights on how disturbance may interact with physical habitat features. Managers can use information on roost-site selection when developing plans to increase probability of crane use at existing roost sites and to identify new areas for potential use if existing sites become limited

Effects of cold winters and roost site stability on population development of non-native Asian ring-necked parakeets (Alexandrinus manillensis) in temperate Central Europe – Results of a 16-year census

Asian ring-necked parakeets (Alexandrinus manillensis, formerly Psittacula krameri, hereafter RNP) first bred in Germany in 1969. Since then, RNP numbers increased in all three major German subpopulations (Rhineland, Rhine-Main, Rhine-Neckar) over the period 2003–2018. In the Rhine-Neckar region, the population increased to more than fivefold within only 15 years. Interestingly, there was no significant breeding range expansion of  RNP in the period 2010–2018. In 2018, the total number of RNP in Germany amounted to >16,200 birds. Differences in RNP censuses between years were evident. Surprisingly, cold winters (extreme value, −13.7 °C) and cold weather conditions in the breeding season (coldest month average, −1.36 °C) were not able to explain between-year variation. This finding suggests that in general winter mortality is low – with exceptions for winters 2008/2009 and 2009/2010, and a population-relevant loss of broods is low in our study population. Surprisingly, the social behaviour in terms of spatio-temporal stability of roost sites could well explain positive and negative population trends. Years of spatially stable and regularly used roost sites seem to correlate with increasing population sizes. In contrast, known shifts of RNP among different roost sites or the formations of new roost sites by split are related to population stagnation or a decrease in numbers. Climate change may lead to further range expansion as cities not suitable yet for RNP may become so in the near future.

Characteristics and Use of Wild Turkey Roost Sites in Southcentral South Dakota

Ten radio-tagged wild turkeys (Meleagris gallopavo)were monitored to document roost site use and bird movements in the Missouri River breaks complex of southcentral South Dakota during the summer of 1984. Distances between roost sites used by wild turkeys ranged from 0.55 km to 3.09 km. Primary and secondary roost sites were identified. Turkeys used one primary roost site consistently every night during periods ranging from a few days to 2 months, then moved to other primary roost sites. Secondary roost sites were used inconsistently by only a few birds that occupied the roost one night, and did not return on subsequent nights. Vegetative characteristics were sampled in roost plots and compared to control plots using discriminant analysis and analysis of variance. Total basal area explained the most variation between all roost plots and all control plots. Wild turkeys selected forested regions with relatively large basal areas. Roost plots averaged 30.2 m /ha while control plots averaged 13.12 m2 /ha. American basswood (Tilia americana) and eastern cottonwood (Populus deltoides) classifications comprised 81% of roost plots sampled and chi-square analysis indicated strong selection by turkeys for these 2 tree species

Roost availability may constrain shorebird distribution:Exploring the energetic costs of roosting and disturbance around a tropical bay

High tides force shorebirds from their intertidal feeding areas to refuges known as roosts. This paper explores the energetic costs of roost disturbance of great knot (Calidris tenuirostris) and red knot (C. canutus) at Roebuck Bay, North-western Australia, assessing disturbance levels at different roost sites through direct observation and automatic radio-telemetry, and applying physiological equations and predictive roost choice models to estimate energetic costs of disturbance through a complete tidal cycle. The study area had a variety of roosts, but use of each was constrained by conditions of tide and time. The roost most suitable for shorebirds on daytime high tides of intermediate height experienced high levels of disturbance from both natural sources (birds of prey) and humans. Flight costs caused by disturbance at this site exceeded the costs of flying to and roosting at the nearest alternative roost, 25 km away. However, shorebirds did not roost at the alternate site, possibly because of the risk of heat stress in a prolonged flight in tropical conditions. Increases in disturbance levels at just one of the roost sites of Roebuck Bay would increase energetic costs substantially, and could easily reach the point at which feeding areas accessed from this roost cannot be used without incurring a net energy deficit. Roost availability can therefore limit access to feeding areas and hence limit population size. Adequate provision and management of roost sites is accordingly an important consideration in conservation of sites used by coastal shorebirds. (c) 2006 Elsevier Ltd. All rights reserved

Vultures

Black and turkey vultures cause problems in several ways. The most common problems associated with vultures are structural damage, loss of aesthetic value and property use related to offensive odors and appearance, depredation to livestock and pets, and air traffic safety. Management of these diverse problems often can be addressed by targeting the source of the birds causing the problem, namely the roost where the birds spend the night. Often the roost itself is the problem, such as when birds roost on a communication tower and foul the equipment with their feces or when they roost in a residential area. There, droppings and regurgitations create odors and their presence is perceived as a threat by the homeowners. Several methods are available for roost dispersal. As in many other situations, roost dispersal might best be accomplished through the integrated use of more than one damage management method. The details of the situation will dictate which management approach is the most appropriate, and experience has shown that best results are obtained if the source roost can be dispersed

Sandhill Crane Roost Selection, Human Disturbance, and Forage Resources

Sites used for roosting represent a key habitat requirement for many species of birds because availability and quality of roost sites can influence individual fitness. Birds select roost sites based on numerous factors, requirements, and motivations, and selection of roosts can be dynamic in time and space because of various ecological and environmental influences. For sandhill cranes (Antigone canadensis) at their main spring staging area along the Platte River in south-central Nebraska, USA, past investigations of roosting cranes focuse donphysical channel characteristics related to perceived security as motivating roost distribution.We used 6,310 roost sites selected by 313 sandhill cranes over 5 spring migration seasons (2003–2007) to quantify resource selection functions of roost sites on the central Platte River using a discrete choice analysis. Sandhill cranes generally showed stronger selection for wider channels with shorter bank vegetation situated farther from potential human disturbance features such as roads, bridges, and dwellings.Furthermore, selection for roost sites with preferable physical characteristics (wide channels with short bank vegetation) was more resilient to nearby disturbance features than more narrow channels with taller bank vegetation. The amount of cornfields surrounding sandhill crane roost sites positively influenced relative probability of use but only for more narrow channels \u3c100m and those with shorter bank vegetation. We confirmed key resource features that sandhill cranes selected at river channels along the Platte River, and after incorporating spatial variation due to human disturbance, our understanding of roost site selection was more robust, providing insights on how disturbance may interact with physical habitat features. Managers can use information on roost-site selection when developing plans to increase probability of crane use at existing roost sites and to identify new areas for potential use if existing sites become limited

Radar quantification, temporal analysis and influence of atmospheric conditions on a roost of American Robins (\u3ci\u3eTurdus migratorius\u3c/i\u3e) in Oklahoma

Radar observations present a way to monitor large, mobile populations across long temporal scales, and are especially valuable when individual scatterers are challenging to count visually. The focus of this study is a large and relatively homogeneous wintertime roost of American Robins (Turdus migratorius) in central Oklahoma. Radar observations are used to estimate the roost population through winter 2010–2011, and the population time series is related to weather variables and radar beam propagation. Radar-estimated roost population gradually increased to an estimated peak of 1.5–2 million individuals from November 2010 to January 2011, and then decreased in a more stepwise manner through the spring until roost dispersal in early March. Weather conditions did not definitively explain these population decreases leading toward roost dispersal. Birds from the roost were often observed to travel \u3e50 km away during the daytime. About 25–30% of the variability in the radar-derived roost population estimate could be explained by atmospheric variables. This work provides an example of how radar methods may be used to estimate populations and monitor their temporal trends, which may be valuable to conservation efforts by facilitating estimates of population change through time

Seasonal fluctuations in urban roost use by Brazilian free-tailed bats (Tadarida brasiliensis) in a highway overpass, San Angelo, Texas

I surveyed a large population of Tadarida brasiliensis roosting in a highway overpass in San Angelo, Tom Green County, Texas to determine roost use and seasonal patterns of occupancy. I compared occupancy patterns observed in 2014 to those observed when the site was last surveyed in 1995. Population counts and roost use were documented from February 2014 through February 2015. Bat populations ranged from 0 during some winter counts to an estimated high of 191,795 individuals in August. Rainfall affected roosting conditions. During times of precipitation, large numbers of bats temporarily vacated the roost, but they returned when conditions improved. I discovered that this roosting location for T. brasiliensis serves as a maternity roost during the summer. Compared to a previous study conducted on the same roost in 1995, there were similar trends in seasonal occupancy. I concluded that the colony at this roost fluctuates predictably year-round

Man-made maternity roost selection by Scotophilus kuhlii (Lesser Asiatic yellow bat) in two anthropogenically altered habitats

Scotophilus kuhlii is a highly gregarious bat that thrives in anthropogenically altered habitats readily roosting in man-made structures. Although widespread, information on the ecology of S. kuhlii is very scarce in Southeast Asia. We conducted this study to determine if the females used the same day roost as a maternity roost in buildings in an agricultural and suburban habitat from July 2013 to April 2015. The females were found to use the same day roost as a maternity roost as the buildings provided a higher temperature and more stable thermal conditions as compared to the ambient temperature. We found that there was a significant positive relationship between roost microclimate and ambient microclimate. Based on the observation of the external body condition, females were found to be seasonally monoestrous. Our findings are useful for conservation and management of these synantrophic bats where natural roost sites are lacking and in managing human-bat conflicts