scholarly journals How hazardous is the Sahara Desert crossing for migratory birds? Indications from satellite tracking of raptors

2009 ◽  
Vol 6 (3) ◽  
pp. 297-300 ◽  
Author(s):  
Roine Strandberg ◽  
Raymond H. G. Klaassen ◽  
Mikael Hake ◽  
Thomas Alerstam
Keyword(s):  
Migratory Birds ◽  
Satellite Telemetry ◽  
Satellite Tracking ◽  
Sahara Desert ◽  
Annual Cycles ◽  
Marsh Harrier ◽  
Circus Aeruginosus ◽  
Course Changes ◽  
Carry Over ◽  
Migrating Birds

We investigated the risk associated with crossing the Sahara Desert for migrating birds by evaluating more than 90 journeys across this desert by four species of raptors (osprey Pandion haliaetus , honey buzzard Pernis apivorus , marsh harrier Circus aeruginosus and Eurasian hobby Falco subbuteo ) recorded by satellite telemetry. Forty per cent of the crossings included events of aberrant behaviours, such as abrupt course changes, slow travel speeds, interruptions, aborted crossings followed by retreats from the desert and failed crossings due to death, indicating difficulties for the migrants. The mortality during the Sahara crossing was 31 per cent per crossing attempt for juveniles (first autumn migration), compared with only 2 per cent for adults (autumn and spring combined). Mortality associated with the Sahara passage made up a substantial fraction (up to about half for juveniles) of the total annual mortality, demonstrating that this passage has a profound influence on survival and fitness of migrants. Aberrant behaviours resulted in late arrival at the breeding grounds and an increased probability of breeding failure (carry-over effects). This study also demonstrates that satellite tracking can be a powerful method to reveal when and where birds are exposed to enhanced risk and mortality during their annual cycles.

Close to the Madding Crowd: How Resilient are Imperilled Mediterranean Urban Wetlands?

2021 ◽  
Author(s):  
Abdallah Aouadi ◽  
Farrah Samraoui ◽  
Laid Touati ◽  
Riad Nedjah ◽  
Lynda Souiki ◽  
...  
Keyword(s):  
Land Use ◽  
Land Use Planning ◽  
Substantial Reduction ◽  
Anthropogenic Pressures ◽  
Conservation Action ◽  
Marsh Harrier ◽  
Long Term Study ◽  
Circus Aeruginosus ◽  
Ixobrychus Minutus ◽  
The Impact

Abstract Investigating how Mediterranean wetlands respond to adjacent land use conversion, is an important first step in mitigating the impact of human encroachment and other environmental stressors. We monitored the composition and structure of waterbird assemblages, in a Mediterranean urban marsh, subjected to severe anthropogenic pressures. Remote sensing indicated that in the last two decades Boussedra Pond was subjected to landfill, resulting in a substantial reduction (~ 50%) of the marsh, while due to a lack of urban planning urban built-up and agriculture areas expanded considerably in its surroundings. Seasonal changes in the diversity of waterbirds, including the globally Endangered (EN) White-headed Duck Oxyura leucocephala and the Near-Threatened (NT) Ferruginous Duck Aythya nyroca, reflected the importance of the site as a staging and wintering area for many migratory species. The long-term study also suggested that breeding waterbirds species respond differentially to the loss and degradation of habitats, as highlighted by the resilience of the synanthropic Moorhen Gallinula chloropus and the disappearance of several breeding marsh specialists, like the Little Bittern Ixobrychus minutus and the Western Marsh Harrier Circus aeruginosus. The study points out the need for both a coordinated cross-sectorial land use planning and an immediate, affordable and sustainable wetland conservation action.

scholarly journals Factors influencing fall departure phenology in migratory birds that bred in northeastern North America

The Auk ◽  
2019 ◽  
Author(s):  
Émile Brisson-Curadeau ◽  
Kyle H Elliott ◽  
Pascal Côté
Keyword(s):  
North America ◽  
Short Distance ◽  
Migratory Birds ◽  
Breeding Habitat ◽  
Temperature Changes ◽  
Migration Timing ◽  
Warm Weather ◽  
Breeding Grounds ◽  
Timing Of Migration ◽  
Migrating Birds

Abstract The phenology of migrating birds is shifting with climate change. For instance, short-distance migrants wintering in temperate regions tend to delay their migration in fall during spells of warmer temperature. However, some species do not show strong shifts, and the factors determining which species will react to temperature changes by delaying their migration are poorly known. In addition, it is not known whether a slower migration or a postponed departure creates the observed delays in fall migration because most studies occur far south of the boreal breeding areas making it difficult to separate those 2 mechanisms. We used 22 yr of data at a northern observatory in eastern North America, at the southern edge of the boreal forest, to examine how 21 short-distance migrants responded to changing temperatures. We investigated if those species responding to temperature share life-history features (i.e. diet, size, total migration distance, breeding habitat, timing of migration). The period of migration in each species was, by far, the most important factor predicting the response of a species to temperature. Eight of the 13 species migrating in October changed their migration onset with temperature (usually by delaying migration by 1–2 days/°C), while the migration timing of none of the 8 species migrating in September was dependent on temperature. Furthermore, the absence of a greater migration delay by birds breeding farther from the study site (i.e. Arctic-breeding birds) suggests the mechanism is a postponed departure rather than a slower migration. We conclude that temperature variations in late fall influence the conditions on the breeding grounds, so that birds still present at that time benefit more from postponing their departure in warm weather.

scholarly journals Detoured flight direction responses along the southwest coast of Lake Erie by night-migrating birds

The Auk ◽  
2019 ◽  
Vol 136 (3) ◽  
Author(s):  
David V Gesicki ◽  
Erica L Cech ◽  
Verner P Bingman
Keyword(s):  
Lake Erie ◽  
Migratory Birds ◽  
Western Basin ◽  
Good Opportunity ◽  
Infrared Observations ◽  
The North ◽  
Flight Direction ◽  
Breeding Grounds ◽  
Topographical Feature ◽  
Migrating Birds

Abstract Migratory birds encounter the Great Lakes while moving through eastern North America toward breeding grounds to the North, which offers a good opportunity to study variation in migratory behavior as birds face a potentially influencing topographical feature. Using passive infrared technology, we documented the direction of relatively low-flying, nocturnal, mostly passerine migration in spring along the southern coast of Lake Erie’s western basin. We examined the extent to which spring migrants flew across Lake Erie as a continuation of the inland, northeasterly broad front migratory direction, as determined by weather radar and infrared observations, or displayed a tendency to deviate to more closely follow the direction of the coastline. We found that an estimated 62% of all low-flying migrants deviated their flight directions toward the coast of Lake Erie at 2 coastal sites, Cedar Point and Ottawa, which were characterized by northwest–southeast oriented coastlines. Migrants at a third coastal location, Maumee Bay, which has a more east–west oriented coastline, did not display similarly deviated flight directions. We found that even when winds were energetically favorable for a lake crossing, many migrants still routinely displayed deviated flight directions that approached paralleling the coastline. Further, the mean flight direction at one site, Ottawa, shifted more in the direction of the coastline as the night progressed, suggesting that time of night could influence the shift to a more coastal flight direction. The data indicate that the western basin of Lake Erie acts as a salient topographical feature influencing the flight directions of nocturnal migrants. The data further suggest that birds are making active decisions while in flight, based on current environmental and physiological conditions, about whether to continue to cross Lake Erie or take a coastal detour.

scholarly journals Changes in the waterbird community of the Parc National du Banc d’Arguin, Mauritania, 1980–2017

2020 ◽  
Vol 30 (4) ◽  
pp. 618-633 ◽  
Author(s):  
THOMAS OUDMAN ◽  
HANS SCHEKKERMAN ◽  
AMADOU KIDEE ◽  
MARC VAN ROOMEN ◽  
MOHAMED CAMARA ◽  
...  
Keyword(s):  
East Atlantic ◽  
The Past ◽  
Marsh Harrier ◽  
Circus Aeruginosus ◽  
Atlantic Flyway ◽  
Banc D’Arguin ◽  
East Atlantic Flyway ◽  
Red Knot ◽  
Made In ◽  
Banc D'arguin

SummaryThe Parc National du Banc d’Arguin in Mauritania hosts the largest concentrations of coastal waterbirds along the East Atlantic Flyway. In spite of this importance, a review of the changes in the numbers of waterbirds in the area is lacking since the first complete count in 1980. Here we analysed the seven complete waterbird counts made since then, and the additional yearly counts made in one subunit (Iwik region) since 2003. We present evidence for changes in the community composition of waterbirds over the past four decades. Total waterbird numbers showed a decrease between 1980 and 2017, with only Great White Pelican Pelecanus onocrotalus showing a significant increase in numbers. Five species showed significant declines: Long-tailed Cormorant Phalacrocorax africanus, Red Knot Calidris canutus, Bar-tailed Godwit Limosa lapponica, Eurasian Curlew Numenius arquata, and Western Marsh Harrier Circus aeruginosus. In the remaining species, the variation in numbers between counts was too large, and the number of complete counts too small, for trends to be detected. The yearly counts at Iwik region also showed sharp decreases in the numbers of Red Knot, Bar-tailed Godwit, and Marsh Harrier, but not of Long-tailed Cormorant and Eurasian Curlew. A multivariate analysis revealed a significant change in species composition over time, which was caused mainly by changes in the species depending on the intertidal mudflats for feeding (generally in decline) vs. the species depending on fish and crustaceans in the sublittoral and offshore zones (often showing increases).

scholarly journals Polychlorinated biphenyls in raptor and owl eggs in the Czech Republic

2012 ◽  
Vol 48 (No. 12) ◽  
pp. 363-368 ◽  
Author(s):  
I. Kustova ◽  
M. Vavrova ◽  
ILiterak
Keyword(s):  
Czech Republic ◽  
Tyto Alba ◽  
The Czech Republic ◽  
Pcb Congeners ◽  
Milvus Migrans ◽  
Marsh Harrier ◽  
Black Kite ◽  
Circus Aeruginosus ◽  
Lipid Weight ◽  
Aquila Heliaca

In 2001, raptor and owl eggs were collected for the purpose of detection of contamination by poly­chlorinated biphenyls (PCBs) at 15 sites in the southeastern area of the Czech Republic. In total 31 unhatched eggs of 4 raptor species and 3 owl species were examined. PCB determination was carried out by high-resolution gas chromatography. PCB content was expressed in μg per 1 kg of lipid weight for the major PCB congeners 28, 52, 101, 118, 138, 153 and 180, serving as indicators. In all examined eggs the indicator PCB congeners were found. The ranges of total values of indicator PCB congeners found in different raptor and owl species were as follows: kestrel (Falco tinnunculus) 37.0 and 44.3 (n = 2), black kite (Milvus migrans) 28.3–40.5 (n = 3), imperial eagle (Aquila heliaca) 66.4 (n = 1), marsh harrier (Circus aeruginosus) 45.1 (n = 1), barn owl (Tyto alba) 20.6–46.1 (n = 17), long-eared owl (Asio otus) 32.0–41.9 (n = 6) and tawny owl (Strix aluco) 47.5 (n = 1) μg/kg of lipid weight. PCB congener 153 was the one most frequently found.

scholarly journals Geographical and temporal flexibility in the response to crosswinds by migrating raptors

2010 ◽  
Vol 278 (1710) ◽  
pp. 1339-1346 ◽  
Author(s):  
Raymond H. G. Klaassen ◽  
Mikael Hake ◽  
Roine Strandberg ◽  
Thomas Alerstam
Keyword(s):  
Wind Direction ◽  
Bird Migration ◽  
Satellite Telemetry ◽  
Pandion Haliaetus ◽  
Behavioural Responses ◽  
Circus Aeruginosus ◽  
Flexible Response ◽  
Geographical Regions ◽  
Temporal Flexibility ◽  
Direction Of Movement

Wind and ocean currents may potentially have important effects on travelling animals, as an animal which does not respond to lateral flow will be drifted from its intended direction of movement. By analysing daily movements of migrating ospreys Pandion haliaetus and marsh harriers Circus aeruginosus , as recorded by satellite telemetry, in relation to global wind data, we showed that these raptors allow on average 47 per cent drift. Furthermore, our analyses revealed significant geographical and temporal variation in the response to crosswinds. During some parts of the migration, the birds drifted and in other parts they compensated or even overcompensated. In some regions, the response of marsh harriers depended on the wind direction. They drifted when the wind came from one side and (over)compensated when the wind came from the opposite side, and this flexible response was different in different geographical regions. These results suggest that migrating raptors modulate their response to crosswinds at different places and times during their travels and show that individual birds use a much more varied repertoire of behavioural responses to wind than hitherto assumed. Our results may also explain why contrasting and variable results have been obtained in previous studies of the effect of wind on bird migration.

scholarly journals Summer pre-breeding movements of Eleonora’s Falcon Falco eleonorae revealed by satellite telemetry: implications for conservation

2013 ◽  
Vol 23 (4) ◽  
pp. 487-494 ◽  
Author(s):  
UGO MELLONE ◽  
PASCUAL LÓPEZ-LÓPEZ ◽  
RUBÉN LIMIÑANA ◽  
VICENTE URIOS
Keyword(s):  
Migratory Birds ◽  
Satellite Telemetry ◽  
Population Level ◽  
Western Mediterranean ◽  
Breeding Period ◽  
Long Distance ◽  
Priority Species ◽  
Wintering Areas ◽  
Eleonora’S Falcon ◽  
Falco Eleonorae

SummaryRecent advances in bird tracking technologies are revealing that migratory birds use temporal staging sites other than breeding and wintering areas, and these areas deserve conservation efforts. Eleonora’s Falcon Falco eleonorae is a long-distance migratory raptor that breeds colonially on islands and is considered a priority species for conservation. Anecdotal observations indicate that during the pre-breeding period, Eleonora’s Falcons stay in inland areas far away from the colonies, but, to date there are no detailed data concerning the connectivity between these areas and breeding colonies. Using satellite telemetry, we analysed data from four summering events belonging to three individuals breeding in two colonies in the Western Mediterranean (Spain). All of them made inland movements in areas up to c.400 km distant from the respective breeding colonies, visiting several habitats, from forests to arable lands, probably taking advantage of high densities of insects. Perturbations occurring in these areas could threaten Eleonora’s Falcons with serious consequences at the population level. We suggest that conservation measures implemented at breeding and wintering grounds may not suffice and that temporary staging areas should be identified at a larger scale and deserve protection as well.

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