If a bird should use a vessel to recover during migration over sea I guess there is an easy way to detect this. If you have frequent enough GPS signals, you would then expect to have periods (longer or shorter) with speeds that equal or are lower than the speed of a large vessell and are much lower than the normal speed (or even the medium speed) outside this periods. But I have no idea how frequently migrating birds would use vessels anyway. Could the track of the bird that you mention be the result of exceptional good weather and wind conditions? Did you check this?

Unfortunately the presentation I was given has not been published. But for the red kite it has been confirmed that the GPS track of the bird and a specific vessel were identical and even a picture has been taken with the bird sitting on board.

This is interesting but maybe an exceptional case? How long did the bird "stay" on the ship (distance, time)?

I am sorry not being able to answer that. You might get in touch with Rainer Raab. He is as well on Researchgate.

OK, thanks Jürgen, I will contact Rainer.

all the best

Anny

Dear Jürgen Berlin,

Contrary to other species, Montagu’s Harriers often cross the Mediterranean at wide points in long flights. There are individuals that use short crossings at e.g. Gibraltar, but many just cross where they reach the coast. The flights can be prolonged into the night or even next day and normally only take place in favorable weather conditions. We have not yet observed in our data that a bird uses vessels to cross the sea, but it might happen occasionally.

Kind regards,

Almut Schlaich / Tonio Schaub / Raymond Klaassen

We had a young Lesser Spotted Eagle (Clanga pomarina) crossing the Mediterranean Sea from Greece to Egypt which is very unusual. They are soaring birds which normally go arround the Mediterranian via the Bosphorus.

This bird stopped on a ship for one hour late in the evening/night not very far from the African c oast. Unfortunately this bird had a 2D GPS transmitter not giving speed, altitude and direction. Nevertheless was it easily visible because of the change of direction and lower average speed.

We mention one case of a ship-assisted honey buzzard in a recent paper on juvenile honey buzzard migration: Article Wind conditions and geography shape the first outbound migra...

Here is a quick and dirty map showing that event in more detail with each location coloured according to the time of the day, 00:00 being blue and 23:59 being red. This particular bird died shortly after in North-Africa, one of few juveniles to die on the first autumn migration, indicating it may have stopped on a ship because it was in poorer condition than other birds. However, we cant exclude the possibility that it was still in good condition at least before it started its unusually long and risky crossing. Because this bird flew in a WSW direction for most of its flight between Italy and Tunesia it flew a much longer distance over water than it could have done by following a more SW travel direction like other juveniles. Wind conditions dont account for the odd travel direction of this bird. Why the bird flew WSW instead of SSW remains unknown.

The one event described in our paper and above is exceptional within our sample. Although adults continue flying overland to the southern tip of Greece before crossing more than juveniles, repeatedly tracked adult honey buzzards also crossed the Mediterranean at seemingly risky places, where the crossing is long, in some years. Once out of mainland Europe adults ignored most islands near their flight path. Out of 30+ juveniles and 5 adults from Finland that crossed the sea during autumn not one drowned. It seems they can afford to cross the eastern Mediterranean in autumn thanks to prevailing winds that are not too disadvantagous for travel. In spring, however, adults almost never make such long crossings over the Mediterranean as a result of oppossing winds in that season. We are currently working on a new manuscript describing how juveniles learn the strategic detours around the sea throughout their life-time.

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It would be neat to collect all the raptor tracking data of cases where birds stop on ships, quantify their occurence, and couple it to ship tracking data for a short review!

I guess a bird might only use ship when exhausted by unexpected storm or wind. This has been witnessed (although not necessarily for birds on migration), and can be demonstrated using hourly GPS tracking data.

A peregrine fitted with a satellite transmitter that encountered a hurricane, apparently rode a ship into port, then out again once the storm had passed.

McGrady, M. J., Young, G. S. and Seegar, W. S. 2006. Migration of a peregrine falcon Falco peregrinus over water in the vicinity of a hurricane. Ringing and Migration 23, 80 – 84.

I got one track of Eleonora's falcon heading to Madagascar in which possibly it landed on a ship before dying.

One of our GPS-tagged Lesser Black-Backed Gulls used a ship during night when having past Britanny during autumn migration. However, when he woke up in the morning he noted that the ship had brought him in the wrong direction and he (the gull was a male called Eric) continued his flight southward.

An Eurasian Spoonbill marked with colour rings in Italy as chick was observed in Brasil. That bird moved next to ships in Brasilian coast, and it was reported that it used a ship to cross the Atlantic Ocean. Probably, it has lost its way, and it has no other chance to survive in the middle of the Ocean, just to travel on ship. (info via Stefano Volponi)

The biologist, Joseph Szent-Ivány wrote a short article about some Passer domesticus traveling on his sip from Bremerhaven, Germany to Melbourne, Australia (stopping only in Port Said and Suez, Egypt). He noticed the group of birds in ine Suez Canal, and they landed at Australia at the end of the journey.

Szent-Ivány J. (1959): A háziveréb újabb behurcolása Ausztráliába - Aquila, 66: p. 300.

http://epa.oszk.hu/01600/01603/00055/pdf/Aquila_EPA-01603_1959_278-326.pdf

It is also available in english ( The House Sparrow being shipped to Australia.) at the pages 324-325.

According to GPS data, a saker falcon fitted with satellite transmitter in Hungary likely landed on a fishing vessel while being on migration over the Adriatic and encountered severe weather. Two days later she left the vessel when it came near Greek coast.

Also there is a number of articles about peregrines on ships crossing oceans and seas. If you look at this map: https://www.marinetraffic.com/

you will see that the number of vessels on seas is so high that they can easily form "stepping stones" for good flying species between continents.

Yes, birds can sometimes use ships for long sea crossings and that is accidental use, most often because of bad meteorologic conditions. During January 2014, a lot of ornithologists could observe a female of Snowy Owl Bubo scandiacus in France (Ré island). This bird came very probably from North America by ship. In fact, a container ship welcame 7 Snowy Owls near Newfoundland on 9 december 2013 and the birds left the ship near Europe (Spain, France, Netherlands) between 12 and 15 december. Birds can also rarely use ferry-boats to nest. There is a record in Hong Kong of a pair of Barn Swallows Hirundo rustica successfully nesting on a Ferry in 2013 and 2014 (G Welch, com. pers.) and another older record of Northern House-Martin Delichon urbicha in Europe ( DUBOIS P., 1976.- Hirondelle de fenêtre Delichon urbica nichant sur un bateau. Alauda, 44 : 335.).