Journal of Ornithology

West Nile virus (WNV) is an emerging Flavivirus dispersing throughout the American continent. It has emerged in the United States as an important medical and veterinary pathogen. It was introduced into Argentina late in 2004 with reported activity in human, wild birds and equines. Field evidence supports the hypothesis of an enzootic transmission cycle between free ranging birds and mosquitoes. The aim of this research was to analyze the role of autochthonous birds as maintenance hosts. Bay-Winged Cowbirds, Picui Ground Doves and Shiny Cowbirds were subcutaneously inoculated with an Argentinean isolate of WNV. Bay-Winged and Shiny Cowbirds developed relatively low mean peak viremias (102.7 and 103.5 PFU/mL serum, respectively). Picui Ground Doves had the highest peak viremia titers of the longest duration [104.8 log PFU/mL serum (range 102.9–6.2; 4–5 days duration)]. No mortality was observed during the study. The reservoir competence index for each species suggests that an infected Picui Ground Dove leads to ten times more infectious mosquitoes than one infected Shiny Cowbird, and that Bay-Winged Cowbird do not represent a source of infectious virus for mosquito vectors. This is the first study carried out in the region regarding the avian host of WNV in Argentina. However, additional studies, including seroprevalence and reservoir competence of resident birds as well as vector competence, are needed to shed light on the ecology of this pathogen in Argentina.

Two hundred reels of 16-mm film, containing records of a variety of behavior patterns, mostly of dabbling ducks and geese, were discovered in the spring of 2010 in the attic of the Lorenz mansion in Altenberg––original footage, most of them taken by Konrad Lorenz himself, between 1950 and 1958 at his research station in Buldern (Westphalia, Germany) and at the Severn Wildfowl Trust in Slimbridge [Great Britain (now The Wildfowl and Wetlands Trust)]. These films are now available for further analysis at the Konrad Lorenz Institute for Evolution and Cognition Research, Altenberg Austria.

We quantified nocturnal vocal behaviour in a North American temperate mixed-forest community using automated recording. We recorded for 2–4 nights at 32 locations and identified 18 species singing at dawn or dusk. Of those 18 species, only two sang at night (White-throated Sparrow, Zonotrichia albicollis, and Ovenbird, Seiurus aurocapilla). We show that automated recording is a useful tool for studying nocturnal vocalisations.

When early breeding is advantageous, migrants underway to the breeding areas may be time stressed. The timing of sequential events such as migration and breeding is expected to be correlated because of a “domino effect”, and would be of particular biological importance if timings are repeatable within individuals between years. We studied a colour-marked population of Black-tailed Godwits Limosa l. limosa both on staging areas in Portugal and on breeding areas in The Netherlands. For each individual, we measured the timing of the staging period, the arrival date on the breeding area and the egg laying date. We measured average egg volume as a measure of reproductive investment. The date of departure from the staging areas, the arrival date on the breeding areas, and the egg laying date were repeatable among years in individual Black-tailed Godwits. The arrival dates of paired males and females and the average annual male and female arrival dates were correlated. The dates of departure from Portugal, arrival in The Netherlands, and egg laying were not correlated. Earlier clutches had larger eggs than late clutches. If the length of the individually available pre-laying period is accounted for, early arriving birds spent more time on the breeding grounds before laying than late arriving birds. The repeatability of the itineraries and the correlation between arrival timing of males and females are consistent with observations in other migrants. Despite evidence for early breeding being advantageous, we found no evidence of a “domino effect”.

This review covers 40 years of migration studies of the Swiss Ornithological Institute with the tracking radar “Superfledermaus”. Since 1968, this pencil-beam radar was—according to its (military) capacities of surveillance and tracking—applied for two different tasks: (I) To record the intensity of migration at various heights (either based on densities recorded by conical scanning, or frequencies of passage recorded with fixed beams at various elevation angles); densities (birds km−3) and frequencies (birds km−1 h−1) are averages per height intervals of 200 m and do not refer to the position of single targets; they are suited to show average height distributions. (II) Tracking individual birds or flocks provides information on the exact position and flight behaviour of single targets over time. Part I: 16 (among 22) study sites with data from 1991 onwards are chosen to visualize and explain the vertical distribution of nocturnal bird migration according to regionally shaped environmental conditions in the Western Palaearctic and in the trade-wind zone. Average distributions at sites devoid of important orographic or persistent meteorological distortions usually show 20–30% of nocturnal migration in the lowest 200-m interval, 50% below 700 m above ground level (agl), and the 90% quantile reaching heights between 1400 and 2100 m agl. The remaining 10% of migrants are usually scattered up to about 4000 m above sea level (asl). The lower parts of migration are forced upwards when crossing mountain ridges and often remain high after such crossings; at subsequent observation points, migration is often high above ground. Particularly high altitudes prevail where wind conditions are improving with altitude, as e.g. during spring migration in the trade-wind zone. Part II deals with the seasonal and diurnal variation in the spatial distribution of particular bird targets. Birds were on average higher up at night compared to daytime and avoided flights close to the ground in hot desert areas. Highest flights were recorded during diurnal migration above desert areas. The highest 0.3% of the tracked birds were found between 3500 m and 4900 m asl at most sites, but at 5000–6870 m in spring migration of the Mediterranean and the trade-wind zone. The most extreme tracks were at altitudes between 4500 and 6600 m asl above the European mainland, and between 6000 and nearly 9000 m above the Balearic Islands and in the trade-wind zones. A concluding discussion deals with the reasons for generally low flight levels and the particular conditions and requirements of high-altitude migration. Flight conditions in the lower atmosphere deteriorate with altitude. Cost of climbing may impose additional restrictions (specifically for large non-passerines). Decreasing oxygen density imposes limits to high-altitude flight, and compensatory ventilation may induce increased water loss, if no physiological countermeasures are available. High flights are compulsory when crossing high mountain ranges and favoured when wind support increases with altitude. This is particularly true when long non-stop flights lay ahead, when turbulences and/or high temperatures at lower levels can be avoided, and possibly when time for homeward flights in spring can be minimized.

Petrels are among the most threatened group of birds. On top of facing predation by introduced mammals and incidental bycatch, these seabirds have to deal with an emerging threat, light pollution, which is increasing globally. Fledglings are disoriented and attracted to artificial lights in their maiden night flights from their nests to the sea. Once grounded, they are exposed to multiple threats leading to high mortality. We report on numbers of three petrel species (Balearic shearwater Puffinus mauretanicus, Scopoli’s shearwater Calonectris diomedea, and European storm-petrel Hydrobates pelagicus) rescued on the Balearic Islands, Mediterranean Sea, in the period 1999–2013. We assessed the proportion of grounded fledglings in the population and colonies impact based on radiance levels measured from a nocturnal satellite image. We also calculated the radius of light pollution impact. At least 304 fledgling birds were found stranded due to attraction to artificial lights, fatally affecting 8.5 % of them. The proportion of grounded fledglings ranged between 0.13 and 0.56 % of the fledglings produced annually. The body mass of Balearic and Scopoli’s shearwater fledglings decreased with rescue date. Light-induced mortality increased during the fledging period for Scopoli’s shearwaters. Birds were rescued at a mean distance of 4833 m from the nearest colony, and between 30 and 47 % of colonies were exposed to light-polluted areas. Although impact seems to be low for all species, urban development and, consequently, the increase in light pollution in the proximity of the colonies should be taken into account to reduce as much as possible this emerging source of mortality.