Consistency in long-distance bird migration: contrasting patterns in time and space for two raptors

Vardanis, Y., Nilsson, J.-Å., Klaassen, R. H. G., Strandberg, R. & Alerstam, T. (2016). Consistency in long-distance bird migration: contrasting patterns in time and space for two raptors. Animal Behaviour 113: 177–187. doi: 10.1016/j.anbehav.2015.12.014
PDF in ResearGate.net

Abstract :

As the evolutionary responses to environmental change depend on selection acting on individual differences, disentangling within- and between-individual variation becomes imperative. In animal migration research, multiyear tracks are thus needed to estimate the individual consistency of phenotypic traits. Avian telemetry studies have recently provided the first evidence of individuality across space and time in animal migration. Here, we compare repeatability patterns of routes and timing between two migratory birds, the marsh harrier, Circus aeruginosus, and the osprey, Pandion haliaetus, as recorded by satellite tracking. We found interspecific contrasts with low repeatability in timing and duration and a high repeatability in routes for ospreys, but the reverse pattern for marsh harriers. This was mainly caused by (1) larger between-individual variation in routes for ospreys (broad-front migration) than for marsh harriers (corridor migration) and a higher degree of repeated use of the same stopover sites among ospreys, and (2) higher within-individual consistency of timing and duration among marsh harriers, while individual ospreys were more flexible. Our findings suggest that individuality in space and time is not a shared trait complex among migrants, but may show adaptive variation depending on the species’ life history and ecology.

Voir aussi:

Trierweiler, C., Klaassen, R. H. G., Drent, R. H., Exo, K.-M., Komdeur, J., Bairlein, F., & Koks, B. J. (2014). Migratory connectivity and population-specific migration routes in a long-distance migratory bird. Proc. R. Soc. B 281: 20132897.

Maps showing the routes of eight adult ospreys (first row) and six adult marsh harriers (second row) that completed at least one round trip between the breeding grounds in Sweden and the wintering quarters in West Africa during 1996–2012

Maps showing the routes of eight adult ospreys (first row) and six adult marsh harriers (second row) that completed at least one round trip between the breeding grounds in Sweden and the wintering quarters in West Africa during 1996–2012. Each panel highlights the three individuals with most repeated journeys of each species (a: OM1; b: OM2; c: OF1, d: MHM1; e: MHF1, f: MHF2; see Table 1 for details) in blue (autumn) and red (spring), as well as the trips of all other individuals of the species in grey

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The migration of the Great Snipe (Gallinago media): intriguing variations on a grand theme

Lindström, Å., Alerstam, T., Bahlenberg, P., Ekblom, R., Fox, J. W., Råghall, J., & Klaassen, R. H. G. (2016). The migration of the great snipe Gallinago media: intriguing variations on a grand theme. Journal of Avian Biology 47: 321–334.
Free access (now)

Abstract:

The migration of the great snipe Gallinago media was previously poorly known. Three tracks in 2010 suggested a remarkable migratory behaviour including long and fast overland non-stop flights. Here we present the migration pattern of Swedish male great snipes, based on 19 individuals tracked by light-level geolocators in four different years. About half of the birds made stopover(s) in northern Europe in early autumn. They left the breeding area 15 d earlier than those which flew directly to sub-Sahara, suggesting two distinct autumn migration strategies. The autumn trans-Sahara flights were on average 5500 km long, lasted 64 h, and were flown at ground speeds of 25 m s−1 (90 km h−1). The arrival in the Sahel zone of west Africa coincided with the wet season there, and the birds stayed for on average three weeks. The birds arrived at their wintering grounds around the lower stretches of the Congo River in late September and stayed for seven months. In spring the great snipes made trans-Sahara flights of similar length and speed as in autumn, but the remaining migration through eastern Europe was notably slow. All birds returned to the breeding grounds within one week around mid-May. The annual cycle was characterized by relaxed temporal synchronization between individuals during the autumn–winter period, with maximum variation at the arrival in the wintering area. Synchronization increased in spring, with minimum time variation at arrival in the breeding area. This suggests that arrival date in the breeding area is under strong stabilizing selection, while there is room for more flexibility in autumn and arrival to the wintering area. The details of the fast non-stop flights remain to be elucidated, but the identification of the main stopover and wintering areas is important for future conservation work on this red-listed bird species.

The autumn (a) and spring (b) migration of great snipes travelling between the breeding site in Sweden and their winter quarters in central Africa

The autumn (a) and spring (b) migration of great snipes travelling between the breeding site in Sweden and their winter quarters in central Africa. Green dots show the breeding site according to the light geolocators, orange and yellow dots show stopover sites in Europe/northern Africa and sub-Saharan Africa, respectively, and blue dots the final wintering sites. Red solid lines mark the nonstop flights, and grey thin lines show shorter flights.

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Assessing the extinction risk of the great bustard Otis tarda in Africa

Palacín, C., Martín, B., Onrubia, A. & Alonso, J. C. 2016. Assessing the extinction risk of the great bustard Otis tarda in Africa. Endang Species Res 30: 73–82. doi: 10.3354/esr00726 (Open Access)

Abstract:

We studied the dynamics and trend of the last extant population of great bustards Otis tarda in Africa. Moroccan great bustards are the southernmost population of this species, and thus show the characteristics of a peripheral population: small size, isolation and low gene flow. Available counts indicate a severe population decline (62% in the last 15 yr), as well as a contraction of the species’ distribution. We used a population viability analysis (PVA) to evaluate the quasi-extinction risk and to identify the most important threats. The estimated geometric growth rate of the more realistic of a set of possible scenarios was 0.87 (95% CI: 0.85, 0.89). This implies a 13% annual decline over 50 yr. However, projections derived from these results should be interpreted with caution, because models have a great deal of uncertainty and vital rates from Iberian populations may be different from those of the Moroccan population. PVA showed the negative consequence of human-induced mortality. According to the model that best fits our census data and if present threats remain in the coming years, this peripheral population could go extinct in ca. 20 yr. Agricultural intensification, infrastructure developments and new power lines in rural areas where the species occurs are causing habitat destruction and fragmentation and increasing artificial mortality. Urgent conservation measures, especially to reduce human-induced mortality, are needed to save African great bustards from extinction. We suggest that these findings can be generalized to other peripheral great bustard populations living in highly humanized landscapes.

Great Bustard (Otis tarda): a vulnerable species

Great Bustard (Otis tarda): a vulnerable species (Andrej Chudý, via Wikipedia Commons)

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Environmental factors affecting the foraging behavior of herons in Ichkeul National Park, Tunisia

Nefla, A. & Nouira, S. 2016. Environmental factors affecting the foraging behavior of herons in Ichkeul National Park, Tunisia. Waterbirds 39: 99–103. doi: 10.1675/063.039.0112

Abstract:

This study was carried out at Ichkeul National Park, Tunisia, during 2009 and 2010. The influence of environmental variables on the foraging behavior of three Ardeid species was studied. Grey Herons (Ardea cinerea) were the least active of the three species, having the greatest resting percentages in 2009 (55.0%) and 2010 (64.9%); they primarily used the “standing and wait” hunting behavior (68.5%). Great Egrets (A. alba) (93.6%) and Little Egrets (Egretta garzetta) (86.5%) primarily adopted a “walking slowly” strategy. Little Egrets also frequently used the “walking quickly” behavior, a more active hunting technique. Both Little and Great egrets varied their hunting behaviors according to water depth. In shallows, they used the “walking quickly” behavior, while in deeper waters they used the “standing and wait” behavior (Little Egret: r = -0.26, P < 0.001; Great Egret: r = -0.44, P < 0.01). For Little Egrets only, high temperature (F = 42.77, df = 1, P < 0.001) and high wind velocity (F = 63.81, df = 1, P < 0.001) promoted an active “walking quickly” hunting behavior, while high light intensity frequently promoted the “standing and wait” and “walking slowly” behaviors (F = 5.48, df = 1, P < 0.05).

Grey Heron (Ardea cinerea) foraging, Ain Yagout, north-east Algeria

Grey Heron (Ardea cinerea) foraging, Ain Yagout, north-east Algeria (Raouf Guechi Nature & Wildlife Photography)

 

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Significant population of Egyptian Vulture (Neophron percnopterus) found in Morocco

Amezian, M. & El Khamlichi, R. (2016). Significant population of Egyptian Vulture Neophron percnopterus found in Morocco. Ostrich 87: 73–76. doi: 10.2989/00306525.2015.1089334

Abstract:

The Egyptian Vulture Neophron percnopterus population in Morocco has undergone a marked decline since the 1980s to the point of nearing local extinction in the twenty-first century. A field study of some possible sites for Egyptian Vultures was carried out over six days during June 2014 in the Middle Atlas Mountains, Morocco. We counted a total of 48 Egyptian Vultures at three different localities: two occupied breeding sites and one communal roost that hosted 40 vultures of different ages. A (probable) singe adult bird at the breeding site was located and a previously occupied site was also visited. A preliminary survey amongst local people indicated that threats faced by this species are predator poisoning in some areas, and the use of vulture parts for traditional medicine. Given that the species is considered globally Endangered and populations continue to decline in many areas, the discovered population reported here, although relatively small, is of national and regional (North-west Africa) importance. We expect this new situation will revive the hopes for studying and conserving this and other vulture species in Morocco and North-west Africa in general.

Plus de détails:

The plight of the Egyptian Vulture and hopes for the futureBritish Ornithologists’ Union blog.


Sur le sujet des vautours:

Egyptian Vulture (Neophron percnopterus) in Algeria.

Le Vautour percnoptère (Neophron percnopterus) est-il en expansion en Algérie?

Griffon Vultures (Gyps fulvus) at Tikjda (Djurdjura), Algeria (photos + videos).

Adult Egyptian Vulture (Neophron percnopterus), Middle Atlas, Morocco

Adult Egyptian Vulture (Neophron percnopterus), Middle Atlas, Morocco (Rachid El Khamlichi)

Videos of the communal roost of Egyptian Vultures,  Morocco / Dortoir de Vautours percnoptères:

 

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Breeding ecology of Turtle Doves (Streptopelia turtur) on intensively cultivated farmland

Hanane, S. (2016). Effects of location, orchard type, laying period and nest position on the reproductive performance of Turtle Doves (Streptopelia turtur) on intensively cultivated farmland. Avian Research 7: 4.  doi: 10.1186/s40657-016-0039-0 (Open Access)

Abstract

Background
Until recently little was known about factors affecting reproductive parameters of the Turtle Dove (Streptopelia turtur) on intensively cultivated farmland in the Mediterranean area. In this study, the reproductive parameters of this game species were evaluated in relation to location, orchard type, laying period and nest position in central Morocco.

Methods
A total of 317 nests were found and analyzed across five breeding seasons (2004–2008) in the Haouz and Tadla regions, over two major agro-ecosystems made up of olive and orange orchards. Nest position, laying period, clutch size and the number of chicks hatched and fledged per nest were determined on 120 study plots. I used Generalized Linear Models (GLMs) with a Poisson distribution and a log link function, including the logarithm of the number of eggs in each clutch as an offset to model the number of chicks hatched and fledged per nest.

Results
Clutch-size was not affected by location, orchard type, laying period or nest position. The number of chicks hatched per nest differed between orchard types; they were greater in olive orchards (1.33 ± 0.06) than in orange ones (1.03 ± 0.08), whereas the number of chicks fledged per nest consistently differed with laying period and orchard type, which were higher in the early laying period (1.22 ± 0.07) than in the late period (0.93 ± 0.08) and higher in olive orchards (1.22 ± 0.06) than in orange orchards (0.90 ± 0.06). Neither location nor nest position were related to variation in the fledging success of the Turtle Dove.

Conclusions
Olive orchards and the early laying period confer better nesting conditions than orange orchards and the late laying period. Although nest position could be different in each orchard type, it did not affect the breeding success of the Turtle Dove, suggesting that factors other than tree characteristics are influential. Further studies are needed to improve our understanding of the effects of anthropogenic disturbance, especially agricultural activities and hunting, on the productivity of Turtle Dove nests.

 

Turtle Doves: nest with two eggs, newly hatched chick, and adult at nest with its chicks

a) A nest of a Turtle Dove with two eggs on an olive tree. b) A nest of Turtle Dove with a newly hatched chick on an orange tree. c) A Turtle Dove at nest with its chicks on an orange tree (Saâd Hanane)

 

 

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Food from dumps increases the reproductive value of last laid eggs in the White Stork Ciconia ciconia

Djerdali, S., Guerrero-Casado, J. & Tortosa, F. S. (2016). Food from dumps increases the reproductive value of last laid eggs in the White Stork Ciconia ciconia. Bird Study 63: 107–114.  doi: 10.1080/00063657.2015.1135305

Abstract:

Capsule: Accessing extra food from waste dumps increases egg volume and hatching mass in White Storks.

Aim: To test how White Storks vary their investment in egg size, especially in last laid eggs, in relation to food availability, and to improve our understanding of the importance of extra feeding on intra-clutch variation.

Methods: The study was carried out in three White Stork breeding colonies in northern Algeria. Breeding performance was recorded in 70 nests over three years. White Stork colonies situated close to chicken farms were considered to be part of a ‘pseudo experiment’ where parents had access to extra food. Egg volume, laying order, hatching order and hatching weight were recorded.

Results: Egg volume and hatching mass in White Storks was significantly greater when they had access to extra food. The reproductive value of last laid eggs (fourth and fifth) doubled when females had access to extra food.

Conclusion: Laying smaller last eggs within a clutch provides a mechanism to facilitate early brood reduction in the White Stork, and so should be advantageous when food is scarce. On the contrary, when females had access to extra food, last laid eggs were as big as first eggs which suggests egg size variation is adaptable to local conditions.

White Storks (Ciconia ciconia) at nest, Algeria

White Storks (Ciconia ciconia) at nest, Algeria (Ali Mehadji, flickr)

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