Update on 7H in Morocco

It’s been a while since a migration update so it’s clear nothing dramatic has happened!

Although, if you take the long view, there is something very significant. Just look at these two heatmaps prepared by Paul Wildlifewriter.

7H Winter 2014:15 heatmap7H heatmap Spring 2015

Seeing the data presented in this innovative way truly highlights 7H’s shift of focus. We don’t believe heatmaps have been used in Europe on bird tracking data before now; Paul wrote an article in his own blog with more about the work involved. He has to process literally thousands of fixes from a GSM tracker. His presentation of results of data analysis in highly accessible graphics including the heatmaps is greatly appreciated.

Apart from the obvious reduced activity near the mouth of the river (although ironically 7H did go there yesterday!) what else can we learn?

Firstly, 7H is tending to travel further each day than over her first few months near Azemmour. She is still favouring roosts on or near the pylons to the west, yet her hunting focus is further east. The heatmap is red near her roosts because of the daily movement in that area.

Secondly, her trips further upstream are far from daily but are frequent enough to show red on the heatmap. As noted previously, she is often flying at too high an altitude to be hunting during on these outings. The next image shows her heights ASL on a flight upstream on 4 May.

7H upstream early on 4 May

7H upstream early on 4 May

Most upstream outings end roughly where this one did, or just a little further upstream. You can see she flew out at altitude but not in a straight line, then she flew lower as she tracked back along the river. Is she assessing water levels, perhaps – dropping at this time of year – to identify areas which will be shallower for fishing? And then taking a closer look for fish on the return journey? Because she seldom behaves as if she is hunting when on these trips reconnaisance appears the most probable reason for them.

Thirdly, on the Spring heatmap the ‘spike’ from the area around the weir to the farmland she likes to sit in is very prominent. Quite why the farmland is so attractive is a mystery, but it definitely appeals to 7H even more than the wood by the weir.

To end – something not visible on the heatmap is 7H’s choice of a good place to sit early on the morning of 13 May.

The railway bridge south of Azemmour

The railway bridge south of Azemmour

Here is a photo of the railway bridge where she was on top of one of the poles enjoying a panoramic view!

This entry was posted in Abroad, Blue 7H, Osprey updates and tagged , . Bookmark the permalink.

5 Responses to Update on 7H in Morocco

  1. Vic Paine says:

    Thank you Paul, those two graphics distil a vast amount of data into a comprehensive view that conveys 7H’s seasonal movements in an instantly understandable way. It will be interesting to see how the pattern changes again over time.

  2. Vic Paine says:

    Just been having another look at the graphics. One possible interpretation is that the winter range is restricted by higher Osprey population density at this time. Any chance of a similar analysis of UV’s movements.

    • joannadailey says:

      In an earlier post on here we acknowledged that a factor in 7H’s move could be the disappearance of overwintering dominant adult ospreys. It does seem very likely that the main influence is migratory fish, though.

      In Senegal UV has roamed around so much that a heatmap would be of limited value. Also he only arrived there in late January, so fewer seasons to compare.

  3. Vic Paine says:

    I’d agree with you on the hotspots (I presume main fishing areas) but it seems to me that the blue, outer limits cover a much larger overall area when breeding adults are absent. It’s interesting that UV’s movement pattern is so different. I think it will be much more informative if/when we have data sets from more individuals (as long as Paul Wildlife Writer can cope with the amount of data). I can only applaud him for his dedication to analysis of the data, I’ve not seen anything like it anywhere else.

    • joannadailey says:

      Paul is indeed pushing the boundaries. I’m not sure how thrilled he’ll be at your suggestion of a greater workload, Vic!

      In fact, we can’t think of any UK juvenile who has exhibited the level of ‘exploring’ that both 7H and UV undertake. The heatmap for say, Breagha, would have a large red blob with a small blue ring as far as the images on the Loch Garten site show. The same would apply to Lake District’s Number 14 on Bioko. Tweed Valley’s FK8 does range a bit more.

      An update has just been posted on UV; he would have a very large blue outer limit and one squash ball size ‘hotspot’ if you mapped the last month!

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