Migration has started!

by Faisal Al Lamki, Mike McGrady, Andrew Spalton and Bernd Meyburg

Some of the Steppe eagles we have been tracking have started to migrate!

So far at least three of the tagged Steppe eagles have moved away from the wintering area, and headed north (See map below).  This includes 105, which was first fitted with a tag in January 2017, and has spent the last two winters in SW Saudi Arabia.  A fourth eagle is likely on its way as it has not reported in since 25 February.  At that time it was almost at the Oman-Saudi Arabia border.

First movements of three satellite tracked eagles away from their wintering locations.

The gaps in locations are due to the lack of GSM networks in that area, so the tags were not able to upload their data.  They will fill in those gaps, if they stay within a network.  The difference between 105 and the others, is that 105 logs a location every hour.  The others were logging every 10 minutes, though we have now switched those to also log a location every hour.

Consistent with the start of migration documented by these tracked birds, counts of Steppe eagles at the Raysut dumpsite being conducted by biologists at the Office for Conservation of the Environment are declining

Should I stay or should I go?

by Mike McGrady, Bernd Meyburg, Andrew Spalton and Faisal Al Lamki.

Below are maps of Steppe eagles exhibiting the extremes of ranging behaviour (so far... only about a month).  The ranging of the other birds we are tracking, have been something in between these extremes.  For both birds over 2000 locations have been recorded.

185 has been a real stay-at-home eagle, having moved in a limited areas around Raysut, and up onto the escarpment.

Movements of a Steppe eagle (185) during January and February 2019.

182 has headed west into western Yemen.  At its furthest westerly location it was about 30 km south of the town of Taizz.  Below are a map and a photo from the area.

Movements of a Steppe eagle (182) during January and February 2019

Some of the views Steppe eagle 182 might be having.

Steppe eagle 186 during 12-14 February

by Faisal Al Lamki, Andrew Spalton, Bernd Meyburg, and Mike McGrady

The Steppe eagles we are tracking are displaying a variety of ranging behaviours.  Some have moved off to Yemen, some have gone to Yemen and come back, some have wandered away from Salalah but stayed in Oman, and some have stayed fairly close to Salalah, moving only between the rubbish dump at Raysut and night time roosts on the escarpment. 

The map below is of an eagle fitted with a transmitter numbered 186.  Since it was tagged, this bird has travelled to Yemen and returned, and visited the chicken farm north of Thumrayt (green line). 

Movements of a Steppe eagle fitted with a transmitter on 15 January 2019 at Raysut.  Green line is the movement since release, and the white dots are where it was during 14-15 February 2019.

In the last few days  (white dots) it has been about 120 km NW of Salalah.  I can't really make out any features that might cause this bird to dwell there, but something is attractive.  We'll see what happens.

Movements of Steppe eagle 186 during 14-15 February 2019.

In the near future we'll try to post examples of birds of birds that have behaved a bit differently, so check back for new postings

So far...

by Mike McGrady, Bernd Meyburg, Faisal Al Lamki and Andrew Spalton

In January we fitted transmitters to 13 Steppe eagles wintering in southern Oman, and feeding at the rubbish dump at Raysut, near Salalah.  So far the movements of those birds have fallen into three broad groups. 

First, some birds move in a rather limited area south of the escarpment, making regular use of the Rayut rubbish dump, and roosting mostly in forested areas on the escarpment, or nearby.  The map below is an example of this type of movement pattern.

A Steppe eagle's movements during January 2019. This bird has moved in a fairly limited area, feeding during the day at the rubbish dump at Raysut, and roosting at night at various locations on the escarpmet.

Other birds have wandered more widely, including visits to Yemen, but have stayed mostly within about a 100 km radius around Salalah.  Birds in this group also mostly made continued use of the rubbish dump at Raysut, but some seem to have settled farther north. The map below is an example of this type of movement pattern.

A Steppe eagle's movement during January 2019.  This bird moved immediately away from Salalah and flew into Yemen, then returned, and has recently settled near a chicken farm north of Thumrayt,Oman

A third group of birds have flown deeper into Yemen, and have not (yet) returned. See map below.

A Steppe eagle's movement during January 2019.  This bird spent about 10 days around Salalah before moving into east-central Yemen.  The gap in the track is due to a lack of GSM coverage.  When the bird moves into an area of better coverage for an extended period that gap will be filled with logged data.

At first glance, one might be surprised by the differences in movements.  Why do some birds wander so widely or apparently leave southern Oman when there is a reliable source of plentiful food at the rubbish dump at Raysut?  However, in the case of the Steppe eagles, one needs to remember that these birds are migratory, and their journeys back to breeding areas can start in January (ref. migration counts at Eilat).  Also, because the Steppe eagles wintering in southern Oman are surviving as scavengers, and not active hunters, their movements at that time might mimic more those of obligate scavengers (i.e. vultures) rather than active hunters (e.g. Steppe eagles in summer).  So, what we have been seeing over these few short weeks of tracking may be "surprising" simply because these birds are scavenging, and some may be initiating migration.  The fact that we have only been tracking these birds for a few short weeks contributes to the "surprising" nature of the movements, mostly because we know so little about them. 

It is an essential part of the scientific enterprise to admit ignorance, even to exult in ignorance as a challenge to future conquests. - Richard Dawkins