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.

Dispersing blackbirds and starlings from objectionable roost sites

Frightening devices and other methods of dispersing roosting blackbirds and starlings are described along with the techniques for their proper application. In a study in the southeastern United States, exploding shotgun shells and noise bombs were used to disperse roosts of up to 1 million birds. Five roosts containing up to 1 million blackbirds and starlings were 96 to 100% dispersed by two to five people during three to eight evenings of harassment. Dispersal cost between $80 and$535 per roost

Iron Age to Medieval entomogamous vegetation and Rhinolophus hipposideros roost in south-eastern Wales (UK)

Karst cave systems are well developed in Wales (UK) and, in some instances, constitute important bat roosts. Ogof Draenen, near Blaenavon in south-east Wales, is the most recent major cave discovery (1994) with already > 70 km of passages explored spanning a vertical range of 148 m. With the exception of one small chamber (Siambre Ddu) located directly above the main Ogof Draenen system, very few bats have been noticed inside. Extensive accumulations of guano, attributable to Rhinolophus hipposideros, are however found in parts of the Ogof Draenen system. In places covering many square meters and sometimes building heaps > 0.5 m thick, these represent volumes not yet found in any other cave system in the British Isles. Although the date of the abandonment of the main Ogof Draenen system as a bat roost remains unknown, six radiocarbon dates on guano from Ogof Draenen place the occupation in the Iron Age to Medieval period at least. Palynological analysis was undertaken on ten samples distributed through the cave. Comparisons were made with a moss polster and a lake mud sample from the area to provide a first approximation of the regional modern pollen rain and with two modern guano samples, one from Siambre Ddu and one from Agen Allwedd cave (5 km to the north-west) to provide a temporal comparison with the fossil guano. Agen Allwedd cave currently is one of the largest active roosts for Lesser Horseshoe bats in Britain and lies close to the present northern limit of this endangered species in Europe. The main results are that the cave appears to have been used both as a summer and a winter roost; most of the Ogof Draenen guano is formed within c.1600 14C years and, if the largest heap is continuous, it has accumulated within 750 14C years, i. e. 0.16 mm.year-1; the fossil guano samples reflect a relatively closed oak forest with more abundant ivy (Hedera) and holly (Ilex) than at present; insect-pollinated plants such as Ilex, Acer, Hedera and Impatiens glandulifera are over–represented in the guano samples; in addition to the usual causes of bat roost decline (pesticides, pollution), in the case of Ogof Draenen, we may add entrance blocked by rock collapse and decline of the local forest cover as well as change in its composition

Grackles

Numbering in the tens of millions of birds, grackle populations in North America can cause a variety of conflicts with people. Grackles eat agricultural crops and livestock feed, damage property, spread pathogens, and collide with aircraft. Their large roosts can be a nuisance in urban and suburban areas. A combination of dispersal techniques, exclusion, and lethal removal may help to reduce grackle damage. Grackles adapt easily to human-dominated environments, and exploit human food and other features of human landscapes. Thus, an integrated damage management approach to grackle damage focuses on reducing and eliminating the damage, rather than simply controlling grackle populations. Three species of grackles are present in North America: the common grackle, the boat-tailed grackle, and the great-tailed grackle. A fourth species, the greater Antillean grackle (Q. niger) is present in Puerto Rico. All are part of the Family Icteridae that includes blackbirds, orioles, cowbirds, meadowlarks, and bobolinks. The population status of all three grackle species is considered common to overabundant

Guided by the light: Roost choice and behaviour of urban Rainbow Lorikeets (Trichoglossus haematodus)

1. The formation of large communal roosts is a conspicuous phenomenon associated with a wide range of bird species successfully exploiting urban environments. In many Australian cities, the abundance of the Rainbow Lorikeet (Trichoglossus haematodus), a native parrot, has increased markedly in recent decades, with the species roosting in very large numbers within suburban sites. These roosting locations are noisy and cause significant fouling of the land beneath, resulting in conflict with humans.2. We investigated the selection of roosting sites in this species in Brisbane, Australia, by comparing characteristics of both the general sites of these roosts as well as individual trees used within roosting sites and trees that were avoided.3. Lorikeets used a wide variety of tree types for roosting but demonstrated a clear preference for clumped trees within sparsely treed areas that received significantly more artificial light at night than otherwise suitable sites  and trees nearby.4. These features of roosting sites may enhance the detection of nocturnal predators by Rainbow Lorikeets, suggesting a potential positive impact of anthropogenic lighting. Our findings provide valuable insights into the management of roost-related conflicts in urban areas. We encourage further investigations into the possible benefits of artificial light

What they do in the shadows : habitat utilisation and diet of brown kiwi (Apteryx mantelli) adults within a high-density island population : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Ecology, Massey University, Palmerston North, New Zealand

Exploring the complex interactions between an animal and its spatial environment can reveal much about its biology and behaviour and identify strategies to improve future management. Despite this, surprisingly little research has been undertaken in this field in respect to one of New Zealand’s most iconic endangered species, the brown kiwi (Apteryx mantelli). This thesis aims to produce the most comprehensive report to date of brown kiwi spatial behaviour, investigating the habitat utilisation of brown kiwi adults within a high-density population while they are active at night and when roosting during the day. Additionally, the study examines how habitat utilisation varies, and explores the likely drivers of brown kiwi spatial behaviour including food availability, social/reproductive cues, population demographics and environmental variables. Forty seven radio-tagged brown kiwi adults were tracked across a 1.2km2 study site on Ponui Island from March 2013 to February 2014. The utilisation of major habitat types (forest, scrub, pasture and swamp) by each bird was measured, plotted upon a generated habitat map, and compared to predicted rates based on habitat availability to assess habitat selection. To assess habitat selection while foraging, brown kiwi were tracked at night using radio telemetry and their positions estimated using a triangulation methodology. Exact bird locations were also recorded during the day to evaluate their roost habitat selection. Roost sites were also classified into four different types of roost (tree burrow, soil burrow, surface, swamp site). Brown kiwi faecal samples were collected over this time and compared with pitfall trap samples to analyse diet and identify spatial patterns in foraging behaviour. As hypothesised, brown kiwi selected forest habitat most often for both foraging and roosting, also choosing the more structurally stable tree and soil burrow shelter sites. Other habitat types were utilised much less than predicted, though rates varied between seasons, gullies, demographics and behaviours. Pasture was identified as seasonally important for brown kiwi, utilised increasingly by study birds over summer and autumn when foraging. Additionally, a relationship between their spatial behaviour while foraging and while roosting was recognised for the first time, suggesting that these behaviours are not independent. Invertebrate availability was identified as the primary driver of brown kiwi spatial behaviour, with foraging behaviour trends closely matching nocturnal spatial behaviour. Social and breeding behaviours were discussed as other potential drivers, though further research is required to fully understand these relationships. Research findings confirmed that brown kiwi have an opportunistic diet, appearing to select those invertebrate groups that provide the highest protein input more often in their diet. Foraging strategy changed between seasons and locations, likely driven by a combination of changing invertebrate lifecycles, environmental conditions and dietary requirements. This study has improved our understanding of brown kiwi spatial behaviour, introducing new information and refining previous knowledge. The findings provide valuable information for managers as they work to conserve remaining brown kiwi populations, and will become increasingly relevant in the future as population densities begin to rise

Resilient ecological solutions for urban regeneration

There is a need for biological conservation at the global scale, and urban conservation has the potential to support the delivery of this wider goal. Despite historic trends, efforts are underway to protect and enhance the quality, quantity and accessibility of green infrastructure within cities, including biodiversity features within new developments. However, there are questions over their long-term persistence and function. This paper applies an urban futures resilience analysis to a case study site to illustrate how such concerns may be explored and addressed in practice. The analysis identifies vulnerable sustainability solutions and clarifies the aspects that may be improved. The results suggest that the resilience of these solutions is questionable, even though resilience has clearly been considered. In particular, future compliance with, and enforcement of, planning conditions is questionable. The resilience of these ecological solutions may be improved by including some redundancy, designing for low maintenance, incorporating microclimate buffers and locating features in areas unlikely to be subject to future disturbance. The establishment of endowment funds or other dedicated funding mechanisms should also be explored. The paper also recommends that a futures-based resilience analysis be included within the development planning process

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