Archived 2010-2011 topics: Steppe Eagle (Aquila nipalensis): information requested.

Steppe Eagle Aquila nipalensis breeds widely from Eastern Europe through Central Asia to the steppes of Mongolia. It winters in Africa and western Asia and is currently considered Least Concern on the IUCN Red List because of its large range and population; population trends are not well understood but it is not thought to be declining by >30% over three generations (50 years based on a generation time of 16.6 years).

While population trends have not been assessed for the global population, anecdotal sources suggest it is declining. A large proportion of the global population passes through several migration bottlenecks during spring. Trends in numbers passing through Eilat, Israel in spring reported in the 3rd Symposium on Asian Raptors suggest the average count of absolute numbers of Steppe Eagles has declined from c. 35,000 pre 1987 to c. 9,000 post 1989 (Yosef 2003). Populations in European Russia and Turkey are in decline (BirdLife International 2004), but these constitute <5% of the global population. In Africa in winter (Dowsett et al. 2008) report no apparent change in the number of wintering birds from Zambia.

To ascertain global trends data are needed from the Asian breeding grounds and African wintering grounds. Comments on likely population trends are invited.

BirdLife International (2004) Birds in Europe: population estimates, trends and conservation status. Cambridge, U.K.: BirdLife International (BirdLife Conservation Series 12).

Dowsett, R.J., D.R. Aspinwall, and F. Dowsett-Lemaire. 2008. The birds of Zambia. Tauraco Press and Aves, Liége, Belgium.

Yosef, R. (2003) Raptor visible-migration monitoring, banding and conservation at Eilat on the westernmost Asiatic flyway. Asian Raptor Research and Conservation Network. 3rd Symposium on Asian Raptors, Kenting, Taiwan, 2003.

(This discussion was first started as part of the 2010 Red List update)

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One Response to Archived 2010-2011 topics: Steppe Eagle (Aquila nipalensis): information requested.

  1. Andy Symes says:

    Comments received as part of 2010 update:

    Prof. Reuven Yosef (October 2009):
    this just to notify you that the brunt of the Steppe Eagles has passed Eilat and Major (rtd.) Henk Smit, Holland, undertook the survey at Eilat. This is his 11th year with me doing these surveys. FYI – this has been the worst season ever for the eagles with only 2773 counted to date.

    Johannes Kamp (October 2009):
    Some comments on the situation in Central Kazakhstan, the species’ stronghold (data JK, Maxim Koshkin, Alexei Koshkin et al.) below.

    – in a 30,000 km^2 study area E and S of Lake Tengiz, Akmola oblast’, Central Kazakhstan, anecdotal evidence suggests a stable breeding population 2004-2009, with 20-25 nests found annually without special search (breeding population is larger). Most of the sites were occupied in all of the years. Breeding success was apparently high with most chicks recorded in the nest subsequently fledging (informed guess 80%?) fledging, even in ground and power-line nests close to roads.
    Post-breeding flock size did not decrease 2000-2009 with regular concentrations of up to 50 birds.

    Limiting factors:

    1) Mortality: annually, some juveniles and fewer immatures/adults are killed by road traffic and through electrocution, mostly in July just after fledging. Semi-quantiative studies on electrocution, but without rigorous sampling design, in the above mentioned study area suggest varying temporal and spatial patterns in powerline-related mortality. While there are only very few powerlines which show a dangerous construction (usually Soviet 10kV), some of those claim high death tolls of birds of prey: 7 Steppe Eagles on 29 km walked transect in Sept/Oct 1999 (T. Heinicke unpublished report), but only three unidentified eagles (most probably steppe eagles) were found among 179 buzzards and kestrels at three powerlines surveyed in May and August 2006 (total of 43 km,Lasch et al. in press, download via http://www.afsv.de/download/literatur/waldoekologie-online/waldoekologie-online_heft-9-2.pdf )

    The importance of electrocution is likely to have strongly declined since Soviet times, since many rural settlements were abandoned and power lines dismantled in times of economic hardship, especially the dangerous medium voltage lines which provided precious metal that was often stolen along kilometres and sold for cash.

    2) Habitat and food availability: habitat and food availability for the species have probably increased massively due to significant changes in land use since 1991, namely to two processes (all raw data downloadable at http://www.stat.kz ):

    -collapse of the Soviet cereal farming system in the 1990s (23 Mio ha. cereals sown in 1990, only 11 Mio ha. in 1999, but since then steadily increasing again) with currently still 31% (7 Mio ha.) of the Soviet arable land abandoned and reconverting into steppe

    -collapse of the Soviet livestock system after 1991, with livestock numbers first sharply declining, but strongly increasing again since 2000. Spatial changes in grazing, mostly concentration of livestock around villages due to reduced mobility of their owners, created massive areas of short grazed steppe swards, which were absent or very localized during Soviet times in many regions. These are preferred by a number of bird and mammal species, amongst others the sousliks (ground squirrels) Citellus pygmaeus and Spermophilus major, the latter being the main and key prey of Steppe Eagles. Numbers of these sousliks have seen a rise after 1991 and a range expansion of S. major is currently observed in Central Kazakhstan (spreading around 10-20km north every year, unpubl data JK and Maxim Koshkin). This leads to regular post-breeding congregations of 80-130 steppe eagles within 3 km radius around small villages at the moment (observed 2009 at three villages in Karaganda oblast’, JK et al. unpublished data).

    -stong decrease of Steppe marmot Marmota bobac (major prey species) hunting since 1991, with Marmot numbers currently increasing and recolonizing abandoned fields

    However, it is observed that land use changes again towards an intensified agriculture since the year 2004 with massive areas of abandoned fields to be ‘reactivated’ during the coming years, so a likely decrease in habitat availability is apparent.

    Summary: In Central Kazakhstan numbers probably stable, fledging rates high, habitat and food availability favourable and probably better than in Soviet times. Influence of electrocution unclear, probably having a varying (regionally high) effect on survival. Habitat and food availability expected to decline in near future on Soviet time levels or below.

    Possibly useful action: Abundance estimates and population monitoring across larger areas, statistically sound studies of electrocution-related mortality in combination with population modelling, satellite tracking of birds caught on the breeding grounds.

    ______________________________
    Johannes Kamp
    International Research Section
    Conservation Science Dpt.
    RSPB
    The Lodge
    Sandy
    Bedfordshire SG19 2DL
    UK

    ++44 (0)1767 69-3498
    johannes.kamp@rspb.org.uk

    operations (November 2009):
    The following abstract provides a plausible hypothesis as to why Steppe Eagle numbers may have declined at Eilat:

    The Condor 105:219–227: MIGRATION ROUTES OF STEPPE EAGLES BETWEEN ASIA AND AFRICA: A STUDY BY MEANS OF SATELLITE TELEMETRY. BERND-U. MEYBURG, PATRICK PAILLAT AND CHRISTIANE MEYBURG

    Abstract. We trapped 16 Steppe Eagles (Aquila nipalensis) on migration and on their wintering grounds and fitted them with satellite transmitters, 15 of them in Saudi Arabia and one in South Africa. Seven of the 14 Steppe Eagles trapped in Arabia in autumn did not migrate to Africa but spent the winter in the Arabian Peninsula. One adult migrated to southern Africa. The other six wintered in northeastern Africa, in some cases north of Babel-Mandeb, the straits at the southeastern end of the Red Sea, which they had crossed to reach the African continent. On their spring migration all eagles wintering in Africa migrated via the Suez, Egypt–Eilat, Israel, area at the northern tip of the Red Sea. This loop migration around the Red Sea is probably caused by east winds that blow from October until April, making the return migration difficult via Bab-el-Mandeb. This finding should help to explain the difference in eagle numbers between spring and autumn at such migration bottlenecks as Eilat, Suez, and Bab-el-Mandeb. Unlike eagles coming from Sudan and Ethiopia, eagles wintering in southern Africa must make a considerable detour of over 1200 km to complete this loop. The increase in Steppe Eagles overwintering in Arabia has probably contributed to the decline in the number of birds passing through Eilat in spring during recent years.

    Praveen J (November 2009):
    Recent sightings of Steppe Eagle in South India indicate a likely range extension of this species. It was previously (pre-2000) unrecorded in almost the whole of South India but now recorded sporadically or regularly from several localities in South India during winter.

    Nyambayar Batbayar in 2005:
    according to Mongolian ornithologists, the number of encountering steppe eagles seems to be less than it was 5-10 years before.

    Also there are reported reductions in breeding success and changes in nesting places at some places in central Mongolia in 2004-2005. All of these are explained by low rodent population and consequence of poisons being used against field voles. Again, it is very difficult to properly asses the population status of this species in Mongolia due to lack of reliable scientific data.

    Andrew Dixon (November 2009):
    In Mongolia a significant area of steppe grassland has become degraded. Causes are believed to be climate change, weather conditions and grazing. A symptom of degraded steppe is an increase in rodents esp. Brandt’s Vole and Mongolian Gerbil. These rodents can occur in huge numbers over vast areas providing a significant food resource for birds of prey such as steppe eagle. Degraded steppe grasslands may be beneficial for raptors. There has been no noticable decline in steppe eagles in the central mongolian steppe zone since 2005-09 but quantitative data is limited. Many steppe eagles remain in Mongolia until at least October.

    Johannes Kamp (November 2009):
    This seems to be pretty consistent with the situation in Central Kazakhstan (see above). Is there any quantitative data on trends in vole and gerbil numbers in Mongolia?

    Colin Richardson (January 2010):
    David Stanton & I took a short drive to the outskirts of Sana’a, in Yemen on 22nd & 23rd December 2009 and found at least 150 Steppe Eagles scavenging off chicken remains at a dump.David who is the chairman of the Yemen ornithological society says that this is a regular occurrence and the species is relatively abundant at these slaughterhouse dumps in Yemen.

    Igor Karyakin (January 2010):
    Status Steppe Eagle is rather stable only in the zone of dry steppes of Kazakhstan and in the Altai Mountains during last 10 years. As a result of a high rate of deaths through electrocution noted in all the territory of the range there are too many young birds in breeding pairs in populations. The main reason of the decreasing in the Steppe Eagle number in Russia is the extinction of sousliks as a result of collapse of the soviet system of pasturable livestock breeding. In different regions of the European part of Russia, a number of the species decreased in 5-10 times and in Northern and Southern Kazakhstan – in 2-3 times during 1989-2009. Probably the western populations of the species have yet existed due to young birds emigrating from Steppes of Kazakhstan (because death rate exceeded birth rate in that populations in some years).
    A total of 2304 – 3403 pairs are estimated to breed in Russia in 2009 (data of counts in 2002-2009).
    European part of Russia 1071-1745
    Rostov region 10-30
    Republik of Kalmykia 400-600
    Astrakhan region 50-100
    Volgograd region 300-500
    Saratov region 100-200
    Samara region 11-15
    Orenburg region 200-300
    Republik of Bashkortostan extinct
    Chelyabinsk region extinct
    Asian part of Russia 1233-1658
    Altai Kray 270-280
    Republic of Altai 400-600
    Republic of Khakassia 100-150
    Republic of Tyva 300-400
    Irkutsk region 5-10
    Republic of Burjatia 58-68
    Chita region 100-150

    Igor Karyakin has made the following contribution (February 2010):
    According my surveys during last 10 years, Greater Spotted Eagle in Russia is rather successful and the decreasing of its number seems to be unlikely. The Imperial Eagle and especially the Steppe Eagle are in the more threatened situation. The Steppe Eagle has catastrophically decreased in number for last 10 years, more than in 10 times in some territories, and has become extinct in 3 regions

    Virag has made the following comment from India (March 2010):
    As a part of our project on “Ecological study of Chhari Dhandh- A wetland in Greater Rann of Kachchh (Gujarat, India), we carry out frequent field visits to the area. During the last visit November-2009 we sighted about 7-8 Steppe eagles soaring around this wetland. The species is regularly seen in good numbers every year during winters.

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