Why do bumblebees follow ferries?

Sejero - 20160910_180359.png

A few years ago I mentioned in my post “Garlicky archipelago” that I had seen bumblebees (Bombus spp.) following the ferry from Southampton to the Isle of Wight, a distance of about 1.5km across water.  If I remember correctly it was my colleague Scott Armbruster who first mentioned this to me: he lives on the Isle of Wight and commutes regularly to the mainland.

I’ve not thought much about this since then as 1.5km is a fairly modest distance for a bumblebee to fly.  But then a few weeks ago I saw the same thing in Denmark, but this time over a much longer distance.

Karin and I were visiting friends on the small island of Sejerø, which (at its closest point) is about 8km from the mainland of Zealand.  To get there you have to catch a ferry which takes about an hour to cross this stretch of water.  About half-way across,  whilst looking over the stern of the ship, I spotted a bumblebee following the ferry.

So that’s twice, on two different ferries and under very different contexts, that I’ve seen this phenomenon.  A pattern is starting to form….  Has anyone else observed this?  Please do comment.

I can think of a few explanations/hypotheses for what’s going on here (some of which are not mutually exclusive):

  1.  Clearly bumblebees do fly across significant stretches of open seawater.  Perhaps all I’m seeing is bees that do this, but spotted from the only vantage point where it’s viewable (i.e. the ferry).
  2. These bumblebees are taking advantage of the slipstream created by the ferry to reduce the energy required to fly these long distances.
  3. The bees are hitching a lift on the ferry and I only observe them as they arrive or depart.
  4. The bees are following the wake of the ship to navigate between the island and the mainland, in order to exploit significant flower patches.  Work by one of my PhD students, Louise Cranmer, a few years ago showed that bumblebees follow linear features such as non-flowering hedgerows to navigate – see Cranmer et al. (2012) Oikos.  Perhaps something similar is happening here?

There’s probably other possibilities I’ve not thought of.  But whatever the explanation, it looks to me as if there’s some potential for interesting experiments marking and recapturing bees on islands/mainland, releasing bees on ferries to see if they follow the wake, etc.  If only Northampton wasn’t so far from the coast….

 

 

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21 Comments

Filed under Bees, Biodiversity

21 responses to “Why do bumblebees follow ferries?

  1. Fascinating. It would be interesting to see conclusions in the future.

    Liked by 1 person

  2. Really interesting post/question! I’ve observed this recently while taking a medium sized passenger boat out to the Isle of Staffa from the Isle of Mull. Although all surrounding land masses were visible and this particular bee seemed to be going in the opposite direction from the boat – so most likely your first explaination applies here. On land bumblebees use land marks to navigate to and from their nest sites so would be interesting to find out how island hopping bees find their way home. A ferry is probably a pretty good ‘water mark’ for a bumblebee to use while navigating across a big stretch of water, especially if it has regular sailings but in my experience they generally fly faster than a ferry sails… It would be great to somehow track new queens from island colonies as they disperse to see how far they get.

    Liked by 1 person

  3. Reblogged this on Bad Beekeeping Blog and commented:
    This is a fascinating observation. Bees appear to ‘follow’ ferries across long stretches of open water. Shared at Bad Beekeeping Blog…

    Liked by 1 person

  4. Amazing – I thought bees avoided crossing water. It must be incredibly risky for them. If bees follow ferries, do Asian hornets too?

    Liked by 1 person

  5. I saw a bumblebee when on a ferry to Jersey last year – that is a 3 hour journey. I presumed it had ‘boarded’ the ferry in/on a car and had then flown off but maybe not.

    Liked by 1 person

  6. Because they don’t have satnavs 🐝🐝🐝

    Liked by 1 person

  7. Very interesting from an Australian perspective! Bumblebees are invasives here, currently restricted to Tasmania (an island)…there is a regular ferry service to the mainland, but with a distance of over 200 km, probably not an issue! 🙂 Although could they have hitched a ride on the ferry from port & then were just stretching their legs somewhere out in the ocean?

    Liked by 1 person

  8. peggyclarke

    I am an ocean kayaker and often experience bumble bees flying out to investigate me when paddling around islands. I always assumed they were attracted to the colour of my kayak, like a bright red flower in a sea of blue. Hummingbirds do the same!

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  9. Some more ideas:
    – The bumblebees might have their home on the ferry, where it is dry and warm.
    – The bumblebees might follow not (only) the slipstream, but the warmth of the ferry.
    – The bumblebees are attracted by anything smelling nice on the ferry, maybe even food / flowers, ore dry spaces to lick salt.
    – The bumblebees are accidently on the ferry and you see them when they took of and then try not to be over water and thus follow the ferry.
    – Bumblebees might always have used drifting wood or other objects to reach new places, and a ferry is only a pretty large and fast one.

    It would be interesting to find out if these bumblebees are female, male or both. Any significant size?

    Liked by 1 person

  10. Pingback: Bumblebees, ferries, and mass migrations: an update | Jeff Ollerton's Biodiversity Blog

  11. Pingback: Spiral Sunday #5 | Jeff Ollerton's Biodiversity Blog

  12. I have seen bumble bees on the ferry between Poole and Guernsey. Also one of those large black bees following a ferry between Tangier in Morocco and Spain. I think they get a free ride on the slip-stream and get better nectar from father afield. Its like dolphins who follow boats – they use much less energy.

    Liked by 1 person

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