Is there a connection between weather at departure sites,onset of migration and timing of soaring‐bird autumn migration in Israel?

Aims Different aspects of soaring‐bird migration are influenced by weather. However, the relationship between weather and the onset of soaring‐bird migration, particularly in autumn, is not clear. Although long‐term migration counts are often unavailable near the breeding areas of many soaring birds in the western Palaearctic, soaring‐bird migration has been systematically monitored in Israel, a region where populations from large geographical areas converge. This study tests several fundamental hypotheses regarding the onset of migration and explores the connection between weather, migration onset and arrival at a distant site. Location Globally gridded meteorological data from the breeding areas in north‐eastern Europe were used as predictive variables in relation to the arrival of soaring migrants in Israel. Methods Inverse modelling was used to study the temporal and spatial influence of weather on initiation of migration based on autumn soaring‐bird migration counts in Israel. Numerous combinations of migration duration and temporal influence of meteorological variables (temperature, sea‐level pressure and precipitable water) were tested with different models for meteorological sensitivity. Results The day of arrival in Israel of white storks, honey buzzards, Levant sparrowhawks and lesser spotted eagles was significantly and strongly related to meteorological conditions in the breeding area days or even weeks before arrival in Israel. The cumulative number of days or cumulative value above or below a meteorological threshold performed significantly better than other models tested. Models provided reliable estimates of migration duration for each species. Main conclusions The meteorological triggers of migration at the breeding grounds differed between species and were related to deteriorating living conditions and deteriorating migratory flight conditions. Soaring birds are sensitive to meteorological triggers at the same period every year and their temporal response to weather appears to be constrained by their annual routine.     

Blackaps Sylvia atricapilla stopping over at the desert edge; physiological state and flight-range estimates

Migrating Blackcaps Sylvia atricapilla were mist netted at the desert edge in northern Israel and in Elat (southern Israel) during spring and autumn migrations between 1970 and 1991. Birds in spring in northern Israel were representative of birds that had completed the crossing of the Sahara, while those in Elat still had to cross the 150 km of the Negev Desert, which separates Elat and northern Israel. In autumn, birds captured in northern Israel were representative of those about to cross the Sahara Desert, while those in Elat had already started to cross the desert. The data allowed analysis of seasonal and location differences in the physiological state of Blackcaps before and after crossing the Sahara. Data analysed included body mass, visible fat score and calculated fat content. Autumn migrants were in better physiological condition than spring migrants at both locations, probably as a consequence of their migration route through fertile areas in autumn compared with the crossing of the Sahara in spring. Body mass was less variable after the Sahara crossing in spring than before the crossing in autumn. In spring, 71% and 67% of the birds were fat depleted (fat scores 0 and 1) at Elat and in northern Israel, respectively, while in autumn 34% and 42% were fat depleted. Blackcaps at Elat were 1.6 g lighter than those in northern Israel in autumn and 1.9 g lighter in spring. Potential flight ranges were estimated on the basis of meteorological conditions and flight altitude of passerines above the Negev in Israel (northern Sahara edge) during migration and on a simulation model that considered both energy and water as potential limiting factors for flight duration and distance. The simulation model predicted that half of the Blackcaps that stopped over in Elat and the majority of those that stopped over in northern Israel could not make a nonstop flight over the Sahara Desert in autumn without the assistance of at least an 8 m per s tailwind. Such a wind would still not be sufficient for 34% of the birds in Elat and 42% in northern Israel, and clearly they had insufficient fat reserves to cross the Sahara in a single flight. Although the fattest Blackcaps had accumulated sufficient fat to enable them to traverse the Sahara in a single flight, they probably faced dehydration by at least 12% of their initial body mass when they reached the southern Sahara edge. These birds should use intermittent migration with stopovers at sites with drinking and feeding potential. Their decision to stop over during the day in the desert at sites with shade but without food and water would be beneficial if the meteorological conditions during daytime migration imposed greater risks of dehydration than at night. Spring migrants could not reach their breeding areas in Europe without feeding, but those examined in Elat could cross the remainder of the desert in a single flight.     

The energetic demand of the Great White Pelican during migration in Israel and its implication to the conflict between fish industry and pelicans

Shmueli, M., Arad, Z., Izhaki, I. & Crivelli, A. 2000. The energetic demand of the Great White Pelican during migration in Israel and its implication to the conflict between fish industry and pelicans. Ostrich 71 (1 & 2): 1.

The Great White Pelican Pelecanus onocrotalus is a migrating bird, which is an endangered species. The majority of the western Palaearctic populations stopover in Israel during their autumn migration (71 421 ± 127 individuals per year). Although most of these birds are transient over Israel, an increasing number of individuals (1 142 ± 882, between 1990–1994) stay and winter in the northern part of Israel. The natural feeding sites for pelicans diminished during recent decades due to human activities, and the aquaculture sites of intensive fishery became their favourite feeding places either during migration or during winter. The fish industry reports huge damages to fish yield. This study tried to assess ecophysiological needs of the White pelicans during migration and wintering in Israel, and to evaluate the necessity for pelicans to feed in Israel on their route to east-central Africa. The study combines laboratory measurements of energy consumption of captive pelicans, and field observations of migrant and wintering pelicans, and satellite tracking of migrating pelicans. The mean mass-specific metabolic rate (BMR) of the pelican was 236 kJ/(kg*day), without significant differences between sexes or diets (fish or chicks) and seasons: digestible energy intake (DEI) was 490–730 kJ/(kg*day) also without significant differences between sexes and diets. Wet food consumption (WFC) was greater on the fish diet (1.120 kg/day per bird) than on the chick diet (0.970 kg/day). Digestive efficiency was higher on the fish than on the chick diet (86% and 77%, respectively). Fat deposition in dead migrant pelicans during autumn, was 290 g (3.4% + 2.6% of body mass, n = 81). Fat deposition in wintering pelicans was significantly higher (5.4% ± 3.4% of body mass, n = 21). From these data, the average flight range of transient pelicans was estimated as 1 120 km without refueling. Although satellite records gave us information on the northward migration routes of pelicans from Israel, we need further information about the precise area of the pelicans in Africa. Nevertheless it is concluded that pelicans need to feed during their stopover in Israel, or at some unknown feeding sites along their southward migratory route, to complete their journey to their wintering grounds in east-central Africa. The results of this research should contribute to the establishment of new management policies, to the solution of conflict with the fish industry and to the conservation of pelicans in Israel.     

Moult Strategies Affect Age Differences in Autumn Migration Timing in East Mediterranean Migratory Passerines

Adult passerines renew their flight feathers at least once every year. This complete moult occurs either in the breeding areas, just after breeding (summer moult), or, in some long-distance migratory species, at the non-breeding areas, after arrival to the southern wintering area at the end of autumn migration (winter moult). The aim of this study was to relate moult strategies with the DMD, the difference in median migration date, through Israel, between juveniles and adults. Our data on autumn migration timing in juveniles and adults was based on ringing data of 49,125 individuals belonging to 23 passerine species that breed in Europe and Western Asia and migrate through Israel. We found that DMD was associated with moult timing. In all species that perform a winter moult, adults preceded juveniles during autumn. Among migrants who perform a summer moult, we found evidence of both migration timing patterns: juveniles preceding adults or adults preceding juveniles. In addition, in summer moulters, we found a significant, positive correlation between mean breeding latitude and DMD. Although previous studies described that moult duration and extent can be affected by migration, we suggest that moult strategies affect both migration timing and migration strategy. These two moult strategies (summer or winter moult) also represent two unique migration strategies. Our findings highlight the evolutionary interplay between moult and migration strategies.     

Clutch size of passerines at mid-latitudes: the possible effect of competition with migrants

The clutch sizes of the passerines of Israel and the Cape Province, South Africa, which lie at similar latitudinal range, were compared. Mean clutch sizes in Israel and the Cape Province are 4.09 and 2.87, respectively. Mean clutch size of Israeli migrants is larger than that of residents (4.45 and 3.93, respectively), but no such difference exists in the Cape Province.
It is suggested that the larger clutch size in Israel is a result of two factors: (1) the higher proportion of wintering birds in Israel in comparison with the Cape Province and the presence of many transients there which may compete with resident birds and cause high winter mortality among them and (2) a higher proportion of migrants in the Israel avifauna, which suffer heavy losses during their trans-Saharan migration in comparison with Cape Province migrants, which travel shorter routes. The resulting reduced competition for food during the breeding season in Israel enables passerines there to lay larger clutches as predicted by Ashmole (1963) and Ricklefs (1980).     

The physiological state of captive and migrating Great White Pelicans (Pelecanus onocrotalus) revealed by their blood chemistry

The Great White Pelican Pelecanus onocrotalus is an endangered migratory bird, threatened by diminishing natural feeding sites and by persecution by fishermen. The majority of the migrating White Pelican (71000) stop-over in Israel during their autumn migration to Africa. As part of a larger study, aimed to assess the necessity of feeding during the stop-over in Israel, we examined the blood chemistry of captive and migrating White Pelicans. Blood was sampled from captive birds maintained on a fish diet, after food deprivation for 48 h and from wild birds brought from the field during migration. Food deprivation resulted in increased plasma levels of triglycerides and in lower levels of urea, potassium and calcium. In migrating birds, increased plasma levels of urea and CPK and lower levels of creatinine were revealed. In general, the coefficient of variation in the blood chemistry of migrating pelicans was higher than in the captive birds, that is to say, that these birds were in a variable physiological condition. The blood profile of migrating and wintering pelicans did not indicate a state of dehydration but did indicate energy deficiency. The less extreme changes in blood chemistry of the 48 h food-deprived compared to migrating pelicans suggest that the former did not reach a state of starvation. We conclude that for White Pelicans the stop-over in Israel is a must in order to rest and replenish their fuel reserves for completion of their autumn migration to Africa.     

PRELIMINARY DATA ON THE IMPORTANCE OF ISRAEL FOR THE CONSERVATION OF THE WHITE PELICAN PELECANUS ONOCROTALUS L.

Izhaki, I. 1994. Preliminary data on the importance of Israel for the conservation of the White Pelican Pelecanus onocrotalus L. Ostrich 65:213-217.

The majority of the western Palaearctic populations of the Great White Pelican Pelecanus onocrotalus stop over in Israel during their autumn migration. The annual average number of pelicans observed over Israel in autumn was 71,421±5,027. Although most of these birds were transient over Israel, increasing numbers of individuals (1130±303, between 1990 and 1993) stay and winter in the northern part of Israel. The natural feeding sites for pelicans were diminished during recent decades due to human activities such as the drainage of the Hula swamp in northern Israel 40 years ago. However, intensive fishery and aqua-culture sites became their favourite feeding laces either during migration or in winter. The fish industry complained that the birds seriously affect fish yield. The pelicans not only cause direct damage to the fix industry by predation, but they also transfer nematodes to fish (Oreochromis sp.). As et. there is no solution to the problem of these parasitic nematodes. This preliminary study revealed that the average daily fish consumption per individual was 0,52kg and the small sample size did not indicate any selection for certain fish species or size. Flight range estimation indicated that the pelicans, especially the weak individuals, nee xo feed during their stopover in Israel or in the relatively rare appropriate feeding sites along their southward migratory route over the desert in order to reach their wintering areas in eastern central Africa.     

Genetic characterization of populations of the golden jackal and the red fox in Israel

The golden jackal and red fox are among the wildlife species protected by Israeli law as enforced by the Israel Nature and Parks Authority. In 1964, as a part of a management program to control rabies in Israel, a poison eradication campaign was launched to exterminate golden jackals, considered to be the main reservoir of the disease. The program resulted in the near-complete extermination of jackals in Israel, while foxes were only mildly affected. Jackals have since regained their original numbers and have recolonized southern Israel. We here examined the population structure of the golden jackal and red fox in Israel, 48 years after the poison eradication campaign. DNA from 88 golden jackals and 89 red foxes representing five different geographic regions was extracted and amplified at 13 microsatellite loci in order to characterize the populations on a genetic level. High genetic diversity was found among the jackal and fox populations. A possible migration route through the Jordan Rift Valley was suggested for both species by the genetic similarity of populations in northern and southern Israel. However, in both species, the animals from the center of Israel were distinctive from those north or south, indicating the relative isolation of central populations, likely due to fragmentation or a high abundance of food resources. Genetic profiles obtained for the golden jackal and the red fox in Israel may aid in their conservation management and in the study of zoonotic diseases.     

Spatial and Temporal Distribution of West Nile Virus in Horses in Israel (1997–2013) - from Endemic to Epidemics

With the rapid global spread of West Nile virus (WNV) and the endemic state it has acquired in new geographical areas, we hereby bring a thorough serological investigation of WNV in horses in a longstanding endemic region, such as Israel. This study evaluates the environmental and demographic risk factors for WNV infection in horses and suggests possible factors associated with the transition from endemic to epidemic state. West Nile virus seroprevalence in horses in Israel was determined throughout a period of more than a decade, before (1997) and after (2002 and 2013) the massive West Nile fever outbreak in humans and horses in 2000. An increase in seroprevalence was observed, from 39% (113/290) in 1997 to 66.1% (547/827) in 2002 and 85.5% (153/179) in 2013, with persistent significantly higher seroprevalence in horses situated along the Great Rift Valley (GRV) area, the major birds'' migration route in Israel. Demographic risk factors included age and breed of the horse. Significantly lower spring precipitation was observed during years with increased human incidence rate that occurred between 1997–2007. Hence, we suggest referring to Israel as two WNV distinct epidemiological regions; an endemic region along the birds'' migration route (GRV) and the rest of the country which perhaps suffers from cyclic epidemics. In addition, weather conditions, such as periods of spring drought, might be associated with the transition from endemic state to epidemic state of WNV.     

Energy requirements of migrating Great White Pelicans Pelecanus onocrotalus

The Great White Pelican Pelecanus anocrotalus is the largest migrating bird in Israel and is an endangered species. The Palearctic populations of the Great White Pelican breed in eastern Europe and Asia and most of them pass through the ‘bottleneck’ of Israel to wintering grounds in Africa. Natural feeding sites for pelicans have diminished during recent decades due to human activities, and sites of extensive aquaculture have become the favourite feeding places for wintering and migrating Great White Pelicans. The fish industry has reported a significant impact on fish yield and the conflict between pelicans and fishermen has escalated so that hundreds of pelicans have died in recent years from shooting or accidental electrocution. We approached this management problem by studying the energy requirements of the Great White Pelican during migration and while wintering in Israel, under different feeding regimes (fish or chicks) and in different seasons, in captivity. The results show that a captive bird consumes 1.1 kg of fish per day. The basal metabolic rate and apparent metabolized energy of the Great White Pelican are both higher than predicted from allometric equations. Energetic demands were quite stable on both diets (fish and chicks) and during both seasons (winter and summer). The fat deposits of migrating pelicans averaged 313.5 g compared with 480 g in wintering birds (3.4% and 5.4% of body mass, respectively). Based on these fat contents and on the measured daily energy consumption, we calculated that birds that do not feed in Israel can fly only up to 1620 km from Israel southward and could not cover the distance to their likely wintering grounds in the Sudd area in southern Sudan. However, birds that replenish their fuel reserves could fly up to 2460 km and hence could reach this area. Therefore, we conclude that Great White Pelicans must feed in Israel during the autumn migration in order to complete their journey to Africa. One solution to the conflict between pelicans and fishermen could be to combine deterrents preventing pelicans from feeding in fish‐ponds with the provision of attractive alternative reservoirs, to ensure regular food supplies during autumn.     

Do Levant Sparrowhawks Accipiter brevipes also migrate at night?

Flight paths of visually identified Levant Sparrowhawks Accipiter brevipes on autumn migration were analysed with a tracking radar in the Arava Valley, Israel. This time of the year there are no significant numbers of other species with a similar wing-beat pattern. This wing-beat pattern was found not only in daytime but also frequently at night. It is suggested that the Levant Sparrowhawk uses two strategies of migration: (1) soaring and gliding to reduce energy consumption; (2) flapping flight to reduce time spent on migration. The latter may be more important towards the end of the migratory season and/or when birds have become separated from the main migratory stream.     

The magnitude and timing of migration by soaring raptors, pelicans and storks over Israel

The magnitude and timing of the autumn and spring migrations of 35 species of medium-and large-sized raptors, White Pelicans Pelicanus onocrotalus and White Storks Ciconia ciconia were studied in Israel. Observations were carried out from the ground by a line of observers covering most of the width of Israel across the line of migration and by radar. There was a high correlation between the counts obtained by ground observers and by radar. On average, about half a million raptors (mainly Lesser Spotted Eagles Aquila po-marina, Honey Buzzards Pernis apivorus and Levant Sparrowhawks Accipiter brevipes), 250,000 White Storks and 70,000 White Pelicans passed during autumn, and about a million raptors (mainly Honey Buzzards, Steppe Buzzards Buteo vulpinus, Steppe Eagles Aquila nipalensis and Black Kites Milvus migrans) and 450,000 White Storks passed during spring. Peak numbers were higher–over a million raptors and half a million White Storks. There was high interyear variation in the number of migrants recorded during the study, probably caused by weather and counting efforts. For some species, the whole world (Lesser Spotted Eagle and Levant Sparrowhawk) or Palaearctic (White Pelican) population passes over Israel during migration, allowing an estimate of the world populations of these species. Mean dates of arrival of most raptors are highly predictable, with confidence limits ranging between 1.5 and 5.5 days. The migration periods of White Storks and White Pelicans are longer and their mean day of appearance is less predictable (confidence limits range from 4.2 to 13.8 days). During autumn, 90% of the migrating populations of nocking species, such as Levant Sparrowhawk, Lesser Spotted Eagle, Honey Buzzard and Red-footed Falcon Falco vespertinus, pass within 13, 15, 16 and 18 days, respectively, while nonflocking species, such as Egyptian Vulture Neophron percnopterus, Marsh Harrier Circus aeruginosus and Short-toed Eagle Circaetus gallicus, generally take twice as long to pass. Similar passage periods were recorded in spring. For most species, the autumn migration period was longer than the spring migration period, probably because in autumn adults move before the young birds. Three factors affected the timing and spread of the migration wave: age at first breeding, diet and size of the breeding area.     

On rhythmic movement of the diatom Amphora ovalis

The vertical migration, motility and cell division rhythms of the diatom Amphora ovalis Kütz from Lake Kinneret, Israel, have been studied under laboratory conditions and results compared with comparable rhythms of other unicellular algae. The vertical migration rhythm exhibits two peaks during the light period, both when the cells are kept in continuous light or continuous dark. There is a single peak of motility occurring in the first half of the natural light period and a single peak of cell division in the latter half of the dark period. Rephasing of the rhythm by means of delayed start up time is illustrated and the possible interaction of phototactic and geotactic rhythms discussed.     

Mitochondrial DNA variation, but not nuclear DNA, sharply divides morphologically identical chameleons along an ancient geographic barrier

The Levant is an important migration bridge, harboring border-zones between Afrotropical and palearctic species. Accordingly, Chameleo chameleon, a common species throughout the Mediterranean basin, is morphologically divided in the southern Levant (Israel) into two subspecies, Chamaeleo chamaeleon recticrista (CCR) and C. c. musae (CCM). CCR mostly inhabits the Mediterranean climate (northern Israel), while CCM inhabits the sands of the north-western Negev Desert (southern Israel). AFLP analysis of 94 geographically well dispersed specimens indicated moderate genetic differentiation (PhiPT = 0.097), consistent with the classical division into the two subspecies, CCR and CCM. In contrast, sequence analysis of a 637 bp coding mitochondrial DNA (mtDNA) fragment revealed two distinct phylogenetic clusters which were not consistent with the morphological division: one mtDNA cluster consisted of CCR specimens collected in regions northern of the Jezreel Valley and another mtDNA cluster harboring specimens pertaining to both the CCR and CCM subspecies but collected southern of the Jezreel Valley. AMOVA indicated clear mtDNA differentiation between specimens collected northern and southern to the Jezreel Valley (PhiPT = 0.79), which was further supported by a very low coalescent-based estimate of effective migration rates. Whole chameleon mtDNA sequencing (∼17,400 bp) generated from 11 well dispersed geographic locations revealed 325 mutations sharply differentiating the two mtDNA clusters, suggesting a long allopatric history further supported by BEAST. This separation correlated temporally with the existence of an at least 1 million year old marine barrier at the Jezreel Valley exactly where the mtDNA clusters meet. We discuss possible involvement of gender-dependent life history differences in maintaining such mtDNA genetic differentiation and suggest that it reflects (ancient) local adaptation to mitochondrial-related traits.     

Dates of first arrival and song of birds during 1974–99 in mid-Deeside,Scotland

We studied the wing-length and body mass of the two populations of Reed Warblers (summer breeders and transients), and that of the resident Clamorous Reed Warbler, which exist in Israel. We found that, in all three groups, wing-length increases significantly with age for several years. Body mass also increased slightly (but significantly) with age. These differences were not caused by differential survival of juveniles, but appear to be a general phenomenon, possibly related to better nutrition of the adults. The autumn migration of transient Reed Warblers lasted from August until November, but no adults were captured during October and November, while 29.3% of the first-year birds were captured during these months. This suggests that adults can afford to start migration earlier, perhaps due to their greater experience.     

Routes of migrating soaring birds

Soaring migrants travelling through Israel use three principal routes which are used in the opposite directions during the spring and autumn: (1) the Western Route lies mainly along the western edge of the central mountain range, (2) the Eastern Route lies mainly along the Jordan Valley, crossing the mountain range during part of the day, continuing southward along the Dead Sea towards the Sinai, and joining the Western Route in autumn and (3) the Southern-Elat Mountains Route. The geomorphological structure of Israel, with a central mountain range dividing the country roughly into three landscape units, plays a central role in route selection. In the autumn, the Western Route migration axis is deflected at the beginning of the day from east to west for 10–25 km, depending on weather conditions and the flock's roosting locations. Between 10.00 h and 11.00 h, the daily breeze blowing from the Mediterranean Sea influences the migration axis, which is slowly deflected back to the east. A parallel deflection of the migration axis occurs in the Eastern Route in the autumn. The route moves southwest over the eastern slopes of the central mountain range during the morning hours and over the slope, which absorbs direct radiation from the sun, creating good soaring conditions. Towards late afternoon, when the breeze from the sea starts, the axis is deflected to the east, to the Jordan Valley. In the Elat Mountains, the wind flow plays a similar role, but because the topography of the southern Arava Valley causes a change in wind direction, the axis moves during the day in a north-south direction. In addition to the axis movement on a daily scale, a seasonal deflection of the migration axis from east to west also exists. During autumn migration, early migrants (e.g. White Storks Ciconia ciconia) tend to travel on an eastern route, while late migrants (e.g. White Pelican Pelecanus onocrotalus) travel along the Mediterranean coast. This fluctuation was probably because of sub-optimal soaring conditions along the coastal plain during August. In September, temperature differences between the sea and land decrease and the influence of the marine inversion gradually declines, until its influence disappears completely in October. A comparison of the numbers of soaring birds seen over Israel in the autumn and spring shows significant seasonal differences in the use of the various routes. For example, only one species, the Steppe Eagle Aquila nipalensis, flies over the Elat Mountains in the autumn, compared to more than 30 species in the spring. In the autumn, White Storks pass over only along the Jordan Valley axis, whereas in the spring, about half the migrating storks also pass over the western edge of the central mountain range. Honey Buzzards Pernis apivorus fly along the Western Route in large numbers in the autumn, while concentrating almost totally over the Elat Mountains in the spring. These differences are related to the global migration routes between the breeding and the wintering grounds in relation to the Red Sea, which birds avoid crossing, thus causing them to follow different routes in autumn, and spring.     

African Odyssey project – satellite tracking of black storks Ciconia nigra breeding at a migratory divide

The African Odyssey project focuses on studying the migration of the black stork Ciconia nigra breeding at a migratory divide. In 1995–2001, a total of 18 black storks breeding in the Czech Republic were equipped with satellite (PTT) and VHF transmitters. Of them, 11 birds were tracked during at least one migration season and three birds were tracked repeatedly. The birds migrated either across western or eastern Europe to spend the winter in tropical west or east Africa, respectively. One of the juveniles made an intermediate route through Italy where it was shot during the first autumn migration. The mean distance of autumn migration was 6,227 km. The eastern route was significantly longer than the western one (7,000 km and 5,667 km respectively). Important stopover sites were discovered in Africa and Israel. Wintering areas were found from Mauritania and Sierra Leone in the west to Ethiopia and Central African Republic in the east and south. One of the storks migrating by the eastern migration route surprisingly reached western Africa. Birds that arrived early in the wintering areas stayed longer than those arriving later. On the average, birds migrating via the western route spent 37 d on migration compared to 80 d for birds migrating via the eastern route. The mean migration speed in the autumn was 126 km/d and the fastest stork flew 488 km/d when crossing the Sahara. The repeatedly tracked storks showed high winter site fidelity.     

Biometry and phenology of two sibling Phylloscopus warblers on their circum-Mediterranean migrations

The Mediterranean Sea is known as an ecological barrier for numerous migratory birds flying from European breeding grounds to African wintering sites. Birds generally avoid migration over open sea and fly over land. In the Mediterranean Basin, few land bridges or bottlenecks for migratory birds exist. The narrowest are at the western and eastern extremes: the Strait of Gibraltar and Israel. Comparative studies between these locations are extremely rare to date. Therefore, in order to elucidate the differences between the two flyways, we compared data collected simultaneously for two sister leaf warbler species, the Bonelli’s Warbler complex, Phylloscopus bonelli and Phylloscopus orientalis, at ringing stations in the western Mediterranean Basin Gibraltar, and the eastern Eilat, Israel. Data on biometrics and passage dates of individuals trapped at Gibraltar and Eilat were used, and it was found that mean arrival date of Western Bonelli’s Warblers at Gibraltar was 15 days later than Eastern Bonelli’s Warblers at Eilat. Furthermore, Western Bonelli’s Warblers had shorter wings than Eastern Bonelli’s Warblers. On the other hand, birds in Eilat were in poorer body condition than individuals in Gibraltar. The comparison between geographically distant stop-over sites contributes to furthering our understanding of the development of migration strategies across ecological barriers in sibling species. Our study showed that populations that breed in southwestern Europe migrate through Gibraltar and winter in West Africa are able to accomplish migration in comparatively good body condition. This is in contrast to those that winter in East Africa, migrate through Israel and have to endure the combined challenge of crossing the Sahel, Sahara and Sinai deserts before reaching their breeding grounds across southeast Europe and southwest Asia. Hence, the discrepancies described between the western and the eastern flyway suggest that individuals in the west, in general, migrate shorter distances, have a physiologically less demanding crossing of the North African deserts and appear to stage before their crossing the Strait of Gibraltar, a privilege unavailable to the migrants of the eastern flyway.     

Predation of migratory Little Stint (<Emphasis Type="Italic">Calidris minuta</Emphasis>) by Barbary Falcon (<Emphasis Type="Italic">Falco pelegrinoides</Emphasis>) is dependent on body mass and duration of stopover time

Shorebird (Charadriiformes) migration phenology is critically synchronised with prey availability at traditional staging sites that allows the birds to stage and complete the migrations. These stopovers, usually in large concentrations, make the migrants vulnerable to local predators. The body mass gained or maintained is considered to be the result of the trade-off between the risks of starvation and predation. Theoretically, heavier birds should be less adept at escaping predators, and experimental evidence showed that flight performance is impaired in heavier birds. During three migration seasons we searched pellets and prey remains taken by a pair of Barbary Falcons (Falco pelegrinoides). We discovered that many pellets contained rings from the ringing program in Eilat, Israel, and the overwhelming majority belonged to Little Stints (Calidris minuta). We checked if the body mass and length of the stopover as expressed by ringing status of the Little Stints in a particular migration season was related to the risk of predation by Barbary Falcons. We found the chance that a heavier bird would be predated was lower than that of a lighter individual, and that Stints retrapped during the same migration season were significantly more endangered by predation than those recorded only once.     

The benthic phase of the life cycle ofParapenaeus longirostris (Crustacea,Decapoda, Penaeidae) along the Mediterranean coast of Israel

The population ofP. longirostris along the Mediterranean coast of Israel spends the benthic phase of its life cycle (from body size over 15 mm) on muddy bottom deeper than 45 m. New age groups are recruited within the depth zone of 45–300 m and migrate in both inshore and offshore directions. Inshore migration is limited by unsuitable sandy ground. The limiting line for offshore migration was not found.An age group could be detected during one year within a body size range of TL = 40 mm to TL = 84.5 mm for males and to TL = 102.5 mm for females. Reproductive activity in shallow water, down to a depth of 73 m, takes place during the whole year, while in depths of 150–300 m there is an arrest of reproductive activity from June to August.