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Climate Change
To be sure of definitions, Global Warming is as the name suggests – a climate that is steadily warming. Climate change, again is as the name suggests – changing wind speeds, rainfall, air temperatures etc. Global warming can refer to sea temperature rises too, which the Met people tell me can drive a changing climate, so in some respects the two are linked.
Cheri Lea and Claire Morgan asked which species have shown distinct changes in migration patterns as a result of warming. And linked to this, Penny Cooper asked how long it would be before climate change would conspicuously impact of animal migration. Sue Adams wanted to know whether birds specifically were changing their pattern of migration.
Talking to the experts it’s hard to attribute climate change and warming to any one particular species. But in countries like the UK both non-governmental organisations and governmental research institutes are seeing resident species of butterfly settling in more northerly locations. Indeed the European migrant species, the Painted Lady Butterfly, is going further and further north as average temperatures rise.
Both the RSPB and the British Trust for Ornithology suggest that some species of migrant bird (such as the Sand Martin) might be establishing populations north of the Sahara. The Centre of Ecology and Hydrology (CEH) have observed a northward change in distribution of marine species in the North sea of about 1000km. Most recently, the abundance of snake fish (a type of pipe fish) has soared in the North Sea, so much so that seabirds are feeding this species to their chicks rather than sand eels. The down side here is the chicks cannot swallow the snake fish because of their tough scaly skin and the chicks are dying.
You can find out more in "About WotM", where all our collaborators have their own research on climate change and its impacts on animal migration and distribution.
One important conservation note. Without exception, all the research groups that we talk to, many of whom contribute to World on the Move, imply that climate change shouldn’t be regarded as the only conservation issue. Climate change will have impacts on animal and plant survival in time, but habitat loss, over exploitation of natural resources and pollution are impacting on biodiversity right now. Many organisations are reporting dire species loss and extinction rates, and much of this can be attributed to our impact on our surroundings right now.
Animal Navigation & a bit more
We have lots of questions about animal navigation. Do all species use the same mechanism? How do bull elephants find their way around (from Savanna Banks and Beth Hayward)? I have spoken to many experts in the field of animal navigation and all I can do here is summarise where they are at. It seems that all animals have some sort of direction sense, including us! And all life on earth has an on-board sense of time. A sense of time is used for many life history events, and biologists agree that a clock is needed for animals to use celestial cues to find their way around (using the sun, moon and stars to get a direction - these bodies in the sky move, you need a sense of time to know what time of day it is and therefore be able to compensate for the movement of the sun, moon and stars in the sky).
Many animals can detect the earth's magnetic field over its surface – others have an extraordinary sense of smell, sense of sight and use hearing too. The up sum seems to be that animals can use one or more of the senses above and “choose” which one is best at any one time. It seems they can switch from one to the other on a single migration – so called “cue redundancy”.
Steve Robinson and Helen Ware asked whether light pollution can upset animal navigation, especially in moths. I’m told the answer is yes. Moths avidly use the sun (by the way, there are more day time flying moths than there are species of butterfly!) and the moon to orientate – and bright lights distract them (night time moths are attracted to bright lights – this is how moth traps work and you can see moths around street lights). Jane Lacey asked whether the earthquake in China affected animal migration. The answer here is probably not on the grand scale of things, but locally of course there would be lots of disruption as water courses and habitats are thrown into chaos.
Simon Rushton asked how baby Swallows know their way back to Africa. This is a huge question. It seems likely that the baby Swallow remembers a star map of where it was born, the smell and what the nearby landscape looks like. It’s also clear that they have a genetic pre-disposition to head south and head north at the right time each year. And that is probably it. They know where they have to return to in the spring – and head south during the autumn learning a route south as they go. There’s much debate about this. The Cuckoo is another splendid example of a chick that just seems to know what to do!
John Keith asked where House Martins come from and whether they carry bird flu (presumably the much publicised H5N1 strain). House Martins come from sub-Saharan Africa (both West, East and Southern Africa). Little is known about what wild bird species carry H5N1. Wildfowl have been well publicised for carrying the virus. As to whether you can catch it, our understanding is that this is very unlikely. Although bird to bird infection can be quite virulent crossing to a different animal group remains a rare occurrence.
Elly Daughtry asked whether Swift, Swallow and House Martin numbers are down this year. The British Trust for Ornithology (BTO) have long term records for many British species, and this year want to do a House Martin survey – which we are going to help launch. Following Logie the Osprey this year, we got the strong impression that the spring migration from Africa was a tough one (strong northerly winds in northern Europe). Whether this has impacted on Swallows will become apparent later. Listeners of World On the Move tell me there are less about. Go to our Swallow section in "Species" and you can find sightings by other WOTM listeners.
And Nikki Edwards asked if Eels were entirely dependent on the gulf stream to get back to Europe. Watch this Space. Our Hay Festival special guest Julian Metcalfe (CEFAS) says they are trying to understand the importance of the gulf stream with respect to Eel migration. As an event, World On the Move are going to keep up with this research and we’ll let you all know. Go to the Eel page and have a look around.
Thank you for all your interest! And keep it up, we love hearing from you.
Julian Hector,
Editor of World On the Move