Avian

We examined the occurrence of six species of meadow birds (four wader species and two songbird species) in relation to the distance to the nest location of an avian predator (three species). We related our findings to the degree of openness of the landscape in which this avian predator nest was located. The degree of openness varied from very open to very closed, depending on the number of view-obstructing landscape elements in the landscape (none or very few in open ones, but completely covered with forest or built-up area in very closed landscapes). We used a dataset containing nesting locations of meadow birds and predators in the province of Gelderland, the Netherlands, allowing us to perform the analysis on three grid cell sizes (100 )100 m, 250)250 m and 500)500 m). Our results show that, for each grid cell size, all meadow bird species showed highest nesting densities in open landscapes. Lowered densities were found around occupied nests of avian predators, irrespective whether the predator's nest was situated in an open or closed landscape. The preference of meadow birds for open landscapes away from predator's nests suggests that a large visibility, that allows them to scan for predators to be able to chase them away in time, is an important habitat requirement for meadow birds to select a nest site. It also suggests that openness of the landscape, independent from the presence of occupied predator's nests, is a factor in selecting a nest site. In contrast, for two out of three species of avian predator, we found that they chose more closed landscapes to nest because these species nest in landscape elements like wood lots and lone trees which make the landscape more closed by definition. For the third avian predator species, the grid cell size was probably too small to find a consistent result, as that species has territories larger than even the largest grid cell size we used.

Clostridium colinum is the causative agent of ulcerative enteritis (UE), a serious disease of bobwhite quail (Colinus virginianus) and sporadically of young chickens. The aim of the present study was to develop a polymerase chain reaction assay specific for C. colinum identification. The 16S rDNA sequence of C. colinum was analyzed and two species-specific primers were designed. The specificity of these primers was tested with closely related Clostridium species and the expected amplified product (935 bp) was observed only with DNA from samples containing C. colinum. Results from performing PCR assays on faecal samples from quails spiked with different concentrations of C. colinum showed that the detection limit of the assay was 1.6 x 10 4 colony-forming units per gram of faecal material. This PCR assay can be used in diagnostic laboratories to confirm the presence of C. colinum in pure cultures and could be used to screen enriched samples or faecal samples for the presence of this pathogen.

To evaluate the use of xylazine/ketamine and isoflurane for the induction and maintenance of anesthesia in adult ostriches (Struthio camelus), 7 healthy adult ostriches (weight 100-130 kg) were deprived of food for 12 hours and then given an injection of xylazine (4 mg/kg IM), followed 20 minutes later by an injection of ketamine (8 mg/kg IV). After intubation, each bird was maintained on isoflurane anesthesia, and physiologic and hematologic parameters were measured. The respiratory rate and the systolic, diastolic, and mean blood pressures decreased significantly 10 minutes after delivery of isoflurane, and these decreases continued until the isoflurane was discontinued. Jaw and pedal withdrawal reflexes were useful indicators for evaluating muscle relaxation and depth of anesthesia in the ostriches while under general anesthesia. Recovery from anesthesia was relatively smooth, with minimal complications, and was complete at mean (SD) 50 6 24 minutes after discontinuing isoflurane. From these results, we concluded that induction of anesthesia with xylazine-ketamine followed by maintenance with isoflurane produced sufficient anesthesia for performing surgical operations with relatively smooth recovery in adult ostriches.

Arctic breeding shorebirds travel thousands of kilometres between their wintering and breeding grounds, yet the period over which they arrive and begin to initiate nests spans only several weeks. We investigated the role of local conditions such as weather, snow cover and predator abundance on the timing of arrival and breeding for shorebirds at four sites in the eastern Canadian arctic. Over 11 years, we monitored the arrival of 12 species and found 821 nests. Weather was highly variable over the course of this study, and the date of 50% snow cover varied by up to three weeks between years. In contrast, timing of arrival varied by one week or less at our sites, and was not well predicted by local conditions such as temperature, wind or snow melt. Timing of breeding was related to the date of 50% snow melt, with later snow melt resulting in delayed breeding. Higher predator abundance resulted in earlier nesting than would be predicted by snow cover alone. We hypothesise that when predation risk is high, the value of potential re-nesting exceeds the energetic risks of early breeding. Synchrony of breeding was significantly higher in late breeding years suggesting a relatively fixed date for the termination of nest initiation, after which nesting is no longer profitable.

Poyang Lake is situated within the East Asian Flyway, a migratory corridor for waterfowl that also encompasses Guangdong Province, China, the epicenter of highly pathogenic avian influenza (HPAI) H5N1. The lake is the largest freshwater body in China and a significant congregation site for waterfowl; however, surrounding rice fields and poultry grazing have created an overlap with wild waterbirds, a situation conducive to avian influenza transmission. Reports of HPAI H5N1 in healthy wild ducks at Poyang Lake have raised concerns about the potential of resilient free-ranging birds to disseminate the virus. Yet the role wild ducks play in connecting regions of HPAI H5N1 outbreak in Asia is hindered by a lack of information about their migratory ecology. During 2007-08 we marked wild ducks at Poyang Lake with satellite transmitters to examine the location and timing of spring migration and identify any spatiotemporal relationship with HPAI H5N1 outbreaks. Species included the Eurasian wigeon (Anas penelope), northern pintail (Anas acuta), common teal (Anas crecca), falcated teal (Anas falcata), Baikal teal (Anas formosa), mallard (Anas platyrhynchos), garganey (Anas querquedula), and Chinese spotbill (Anas poecilohyncha). These wild ducks (excluding the resident mallard and Chinese spotbill ducks) followed the East Asian Flyway along the coast to breeding areas in northern China, eastern Mongolia, and eastern Russia. None migrated west toward Qinghai Lake (site of the largest wild bird epizootic), thus failing to demonstrate any migratory connection to the Central Asian Flyway. A newly developed Brownian bridge spatial analysis indicated that HPAI H5N1 outbreaks reported in the flyway were related to latitude and poultry density but not to the core migration corridor or to wetland habitats. Also, we found a temporal mismatch between timing of outbreaks and wild duck movements. These analyses depend on complete or representative reporting of outbreaks, but by documenting movements of wild waterfowl, we present ecological knowledge that better informs epidemiological investigations seeking to explain and predict the spread of avian influenza viruses.