The Case of the Missing House Martins

I love summer in Norfolk. My childhood memories are full of lazy summer days playing in the garden with my little brother. There is one animal which to me just seems synonymous with blue skies and perfect summer days, and that is the house martin. These little birds traveled thousands of miles each summer all the way from Africa to nest outside my bedroom window, bringing with them the promise of some of the sun that they left behind. 
This year I finished my university year and set off on my journey home, feeling much akin to the house martins. I was excited, knowing that they would have beaten me to it, would already be chirping outside my window every morning.

Flying in the sky with their playful flight

But they had not arrived.

They still haven’t. In fact, I have not seen a single house martin this summer. I miss their swooping flight and their chattering outside my window that greeted me every morning. It actually feels like part of summer is missing.

So where are they?

It could be that the birds just decided our house was rubbish and went elsewhere. But having not seen a single bird even flying past, I think this is unlikely.

It is not known where exactly in Africa these little birds overwinter. It is therefore possible that a factor at their overwintering grounds, or even a stopover on the migration route, drastically decreased their numbers. This could be a lack of food, probably linked to climate or some direct human intervention. Either way it looks like we are probably responsible for preventing their return. 

Lastly, there is a possibility that they are just late. If the insect food in the habitat in Africa lasted longer than normal due to a change in climate, then the cues for migrating might come later. I dearly hope that this is the case.

The eaves of the house are covered in nests like this one, empty of any birds.

Whether the birds appear later in the summer, when their breeding success will be reduced, or do not come back at all, this is a timely reminder of our influence on our environment and its far reaching consequences. How many children will have to be denied the wonderful wildlife that I experienced before something is done about it?

The case of the house martin also highlights the need for more research into the complex mechanisms behind migration, and how these are likely to be affected by changes in temperature, food availability and food timing.  The need to discover where the birds go in the winter using tracking devices such as geolocators is also really important, because it is then much easier to conserve the winter habitat. The birds do not just disappear when they leave us in the autumn, and knowing exactly where they go is vital for ensuring that they are back the next summer. I hope we are not too late.

Have you seen any house martins this summer? I would love to know, especially if you have! There is also a link to a survey here if you fancy helping to keep a record of these wonderful birds. If you have never really noticed them before then next time you go outside, look up and see if you can spot them in graceful, swooping flight. I really hope you can.

My Summer Migration

I am currently travelling through the rolling green fields on my journey south for the summer. This is the opposite direction to most summer migrations, and the only preparation I had to make was packing my stuff up. Migrating birds, on the other hand, have to go through a lot more preparation, including building up flight muscles and fat reserves. 

Birds migrate to avoid harsh weather and move to areas with plenty of food (this is also one of my motivations, thanks mum!) Migration is dangerous, exhaustion and predators ready to take advantage of the large numbers of animals all in one place mean that surviving can be a challenge. There is also the possibility that the place the birds are migrating to may not be able to support them. This is an increasing problem with climate change, as insects emerge earlier than they used to and so are not at their peak when the birds arrive. The benefits of migration must be huge for the birds to take all of these risks. My train journey on the other hand, contained no such risks. Aside from the extortionate ticket price and the chance of sitting next to someone a bit weird, of course.

My migration was triggered by the end of my third year at university, and so I have three months to relax before I get back to work. I guess the benefits will be seeing my lovely family and friends. And the free food. Definitely worth the cost of a ticket and nine hours of boredom! 

My navigation home was pretty simple (which is just as well because geography was never my strong subject). I just bought the right tickets, got on a train and hoped for the best. Navigation for migrating birds is much more challenging. They use the sun as a compass alongside an internal clock, which guides them towards their destination. Some birds also use magnetic fields to guide them (it is useful to have more than one method of navigation in case the sun goes in and that method cannot be used). The magnetic field of the earth is stronger towards the north and south poles, and by sensing it using specialised molecules the birds can navigate.

Obviously, all of these methods only work if you know where you are going. So birds need maps, compasses and clocks to find their way to their destination. Much more impressive than me trying to catch a train!!

So now that I am in Norfolk for the summer this blog will hopefully become more frequent. I have swapped the rugged cliffs and mountains of Scotland for the pretty river and marshes of Norfolk, so let the summer commence!