Autumn migration of Montagu’s harriers Circus pygargus tracked by satellite telemetry

Although there is a general understanding of Montagu’s harriers migration routes and wintering areas, detailed information on the species’ migration is still lacking. However, improvements in satellite tracking technology in recent years, have enabled the study of medium-sized species by means of satellite telemetry. In 2006, ten adult Montagu’s harriers were fitted with satellite transmitters in northeastern Spain and tracked during their autumn migration to their wintering grounds in sub-Saharan Africa. The migration took between 10 and 30 days, and the end point was determined using breakpoint regressions. Whereas some birds had stopovers of more than a week, others stayed at the same site for only 1 or 2 days at the most. The tagged birds ultimately established at wintering grounds located along the border of Mauritania with Mali and Senegal, a distance of nearly 3000 km from the breeding sites. These sites are situated within a small range of latitudes (14° and 17°N), although distributed over a wider range of longitudes (−15°E and −4°E), with some birds occupying sites more than 1000 km apart. The distance covered in 1 day during the migration ranged between 93 and 219 km, with peaks of traveling speed of up to 65 km/h. Harriers were recorded traveling only during daytime, covering the longest distances in the late afternoon, suggesting that they are daytime migrants. Most of the distance was covered between 1500 and 2000 hours, and no traveling was recorded between 2000 and 0500 hours. During migration, harriers flew close to the ground (40–100 m on average). Improved knowledge of the harriers’ exact wintering sites may provide insights on the problems Montagu’s harriers face during the winter, highlighting the need to take into account what happens in both the breeding and wintering grounds to implement successful conservation measures.     

Seasonal distribution and dive behaviour of harp seals (<Emphasis Type="Italic">Pagophilus groenlandicus</Emphasis>) of the White Sea–Barents Sea stock

Eight adult female harp seals (Pagophilus groenlandicus) of the White Sea–Barents Sea stock were tagged with satellite-linked dive recorders during the nursing period and followed from breeding in late February 1995 until moulting in late April 1995. Another ten adult harp seals of both sexes were tagged and followed from moult in early May 1996 until breeding in late February the following year. Between breeding and moult the seals were distributed along the coasts of Kola of Russia and eastern Finnmark of Norway, coinciding in time and space with the spawning capelin (Mallotus villosus). Between moulting and breeding they encircled the entire Barents Sea, mostly in open water, using the water column from 20 to 300 m, and in so doing by and large reflecting the annual migrations of the capelin. Capelin is therefore assumed to be the main source of prey for the White Sea–Barents Sea stock of harp seals, to be substituted, in part, by amphipods (e.g. Themisto libellula) in mid-summer and polar cod (Boreogadus saida) and herring (Clupea pallasii) in late autumn and winter. These data provide a baseline for the evaluation of the effects of future climatic change in the rich Barents Sea ecosystem.     

云南大山包越冬黑颈鹤迁徙路线的卫星跟踪

2005年2月26日和3月1日在云南省昭通大山包黑颈鹤国家级自然保护区,分别为4只越冬黑颈鹤佩戴卫星信号发射器(PTTs),跟踪研究其迁徙路线和迁徙停歇地。2005年春季迁徙中,有2只跟踪黑颈鹤到达繁殖地,其中1只黑颈鹤在2005年11月和2006年3月分别完成从繁殖地返回越冬地和从越冬地再次到达繁殖地的迁徙过程。2只春季迁徙黑颈鹤的迁徙路线大致相同——沿着长江上游金沙江、大渡河一直向北到达黄河上游白河及黑河沿岸若尔盖湿地内。春季迁徙过程中,途中停歇3—4次,总迁徙距离是674—713km,迁徙全程所用时间3—4天。秋季迁徙全程所用时间8天。在4个PTTs工作期间,共确定有13个黑颈鹤迁徙停歇地,其中11个停歇地在河流滩地;其他2个停歇地在高山湖泊附近。总体上,黑颈鹤一般选择海拔在1900m以上湖泊、河流等湿地内,距离耕地较近且人、畜干扰较少的栖息地停歇。     

Long-distance migration and homing after displacement in the green turtle (Chelonia mydas): a satellite tracking study

Four green turtle females were tracked by satellite during their post-reproductive migration in the South China Sea. Three of them reached their feeding grounds 923–1551 km distant. During nesting activity, a female was displaced twice, and her return trips to the nesting beach from 11 and 284 km were tracked by a direction-recording data-logger and by satellite, respectively. Part of the journeys occurred coastwise, indicating that leading geographical features had been utilised. The straightness of the turtles' tracks in open seas, both over shallow and deep waters, and their ability to pinpoint distant targets and home after displacement off their usual routes, provides circumstantial evidence for a true navigation mechanism.Abbreviation PTT platform transmitter terminal     

Satellite tracking and avian conservation in Asia

Using satellite tracking, we have followed the migration of birds in Asia for more than 10 years. We have investigated the migration patterns of around 15 species of birds, focusing on, but not limited to, cranes (Gruidae) and storks (Ciconiidae). To relay bird locations, we employed platform transmitter terminals in combination with ARGOS satellites. Location data were then utilized in a variety of applications, from determining migration routes, stopover patterns and wintering sites, through more advanced analyses including using various data overlays to examine habitat use, occupation of nature reserves, differential migration patterns between adults and juvenile birds, and the connectivity and network structure of migration pathways. We have also developed recommendations for spatial improvements to nature reserves. We emphasize the importance of continued empirical research and development of analytical methodologies involving satellite location data in concert with effecting conservation outcomes using satellite-derived data.     

Spatio-temporal overlap between the at-sea distribution of Southern Giant Petrels and fisheries at the Patagonian Shelf

The interactions between seabirds and fisheries pose significant threats for the seabird species such as incidental capture. In contrast, several species of seabirds meet part of their energetic requirements through the use of fisheries discards. Knowledge about the relationship between at-sea distribution of Procellariiformes and fisheries is a key tool in marine ecosystem management. We analysed the spatio-temporal relationship between the areas used by 16 satellite-tracked breeding adults of the Southern Giant Petrel and fisheries distribution and catch at the Patagonian Shelf. We also determined the time spent by adults in different marine jurisdictions. Results indicated a marked spatio-temporal association between birds and fisheries, mainly trawlers. The Southern Giant Petrels concentrated their foraging effort over Argentinean waters. The use of an abundant and predictable food source provided by the fisheries discards may be one of the factors affecting the dynamics of the Southern Giant Petrel populations in Patagonia, Argentina.     

Satellite tracking reveals distinct movement patterns for Type B and Type C killer whales in the southern Ross Sea, Antarctica

During January/February 2006, we satellite-tracked two different ecotypes of killer whales (Orcinus orca) in McMurdo Sound, Ross Sea, Antarctica, using surface-mounted tags attached with sub-dermal darts. A single Type B whale (pinniped prey specialist), tracked for 27 days, traveled an average net distance of 56.8 ± 32.8 km day⁻¹, a maximum of 114 km day⁻¹, and covered an estimated area of 49,351 km². It spent several days near two large emperor penguin (Aptenodytes forsteri) colonies, a potential prey item for this form. By contrast, four Type C killer whales (fish prey specialists) tracked for 7–65 days, traveled an average net distance of 20 ± 8.3 km day⁻¹, a maximum of 56 net km day⁻¹, and covered an estimated area of only 5,223 km². These movement patterns are consistent with those of killer whale ecotypes in the eastern North Pacific where mammal-eating ‘transients’ travel widely and are less predictable in their movements, and fish-eating ‘residents’ have a more localized distribution and more predictable occurrence, at least during the summer months.     

卫星跟踪技术在鸟类迁徙研究中的应用及展望

综述了利用人造卫星跟踪技术进行鸟类迁徙研究的现状和利用卫星遥感技术对鸟类栖息地环境进行分析研究的现状。指出了这两项技术目前存在的问题，提出将这两项技术结合起来将有助于弄清候鸟迁徙定向、迁徙路径选择的机理，揭开候鸟迁徙策略之谜，有助于从景观生态学和保护生物学的角度研究并预测环境变化给候鸟带来的影响。     

地理信息系统及其在动物空间行为研究中的应用

空间属性是动物行为的重要特征,也是行为生态学研究中必须要面对的难题之一。地理信息系统(Geographic Information System,GIS)具有强大的空间分析功能,它在动物行为生态学研究中得到了越来越广泛的应用,如生境选择、领域分析、迁徙路线、活动节律等。本文较系统地阐述了GIS的原理以及在行为生态学研究中所涉及的基本概念和原理,对近年来利用GIS进行的行为生态学研究做了回顾和总结,并对其未来的发展进行了展望。     

Travelling to breed

Traditionally, investigation of the dynamics of avian migration has been heavily biased towards the autumn return trip to the wintering quarters. Since the migratory prelude to breeding has direct fitness consequences, the European Science Foundation recently redressed the balance and sponsored a workshop on spring travels. We here survey the findings elucidating the complications arising during migration directed towards the breeding quarters. The evidence that early nesting confers advantage is overwhelming, hence demands of reproduction pose a constraint on both time and energy resources during spring. Both during migration and upon arrival there must therefore be strong selection in favour of saving time. Experimental results (e.g. using supplementary feeding) show that the date of laying is generally proximately constrained by the inability of the female to find sufficient nutrients. A key question thus concerns the implementation of the ‘capital’ strategy for breeding, the female accumulating nutrient stores along the way to bridge periods of shortage upon arrival on the breeding grounds. Eight studies on waterfowl (geese and eiders) and shorebirds (turnstones and knots) nesting in the arctic combine tracking of individuals (satellite telemetry) with direct observation (marked birds) and reconstruction of the origin of nutrients laid down in the eggs or in the form of body stores of the female parent (stable isotope signatures of tissues compared to potential food sources). The consensus emerges that in most cases a mixed strategy prevails, with nutrients garnered locally supplementing ‘imported’ body stores. The species concerned face a shortage of feeding time during incubation and suffer an energy deficit. Successful breeding thus depends on adequate fat depots that form part of the ‘capital’ the parents bring with them. Some headway has been made in predicting the extent of dependence on body stores for breeding in relation to body mass and length of migration from rates of fat deposition during stopover and fat consumption during flight for waterfowl. This work poses a challenge to refine field studies accordingly. The pressure to save time en route highlights the need to effectively exploit rich food resources. Several case studies underline the crucial significance of a very limited set of stopover sites, each with a narrow time window of optimal harvest. The influence of man at such sites often verges on the disastrous, and ongoing climate change may unhinge the finely tuned timing long-distance migrants depend on. There is a real need to extend this work to provide the scientific basis to underpin adequate conservation actions.