Some birds can’t wait to get back to Africa, and it seems the cuckoos are leading the race. Unfortunately, the reality here is that many species have advanced their migration departure dates due to climate change; it’s warmer, so it seems like the season is more advanced, so off they go.
A couple of years ago I happened upon an amazing website that tracks Common Cuckoos via GPS. Micro-transmitters are attached to the birds and their daily movements are logged. The website uploads daily updates on the cuckoos’ migration progress, providing fascinating insights into the mechanisms of migration.
The crux of the route for many bird species is that rather large tract of inhospitable land known as the Sahara Desert. Barren, to say the least, it’s imperative that birds like cuckoos spend as little time as possible moving through this area of limited resources, and the cuckoos get around the problem by simply flying across the whole thing in as little as 24 hours. A two or three day hop at the most sees them south of the desert lands and into areas of higher resources where they can replenish what can only be severely depleted energy reserves after such a taxing flight. This is an absolutely staggering feat when you consider that the Sahara is wider than 2000km along its western edge, where the majority of these cuckoos are flying.
Most of the cuckoos are spending time in southern Europe to fatten up before flying rapidly over the arid wastes of the Sahara Desert.
Studies have shown that cuckoos favour one of two routes down to Africa; the western route which brings them down through Spain and further south through Morocco or Algeria, and an eastern route which has them descending through Italy and the Balkans and then making a slightly longer hop across the Mediterranean into Libya before heading further south across the desert.
Owing to declines in the cuckoo population in the UK, the study aimed to determine which route was more dangerous for the birds, and where most fatalities were occurring. Interestingly enough, it was before the hazardous desert crossing that most deaths were recorded, which pointed strongly towards changing conditions in the areas in which the cuckoos were stocking up on food supplies before the big leg to West Africa. The main food source of cuckoos is the caterpillars of certain moth species, and it may well be a decline in these numbers that is having a knock-on effect on the cuckoo populations.
Fewer caterpillars ultimately means fewer cuckoos, sure proof that conservation needs to happen on all levels.
I’m a bit irritated with myself, as every year I try to remember to start tracking the individuals before they begin their arduous journey, but I keep missing it. I’ll give myself a little leeway by assuming it’s because they are leaving earlier, but in fact I just assumed they would only be departing around the northern hemisphere Autumn (September). If you visit the website you will see that there are still a fair number of birds that are still in Europe, so we’ll be following their progress with interest.
Down at the opposite end of Africa, we’ve already had the first wave of migrants start to pop up at Londolozi.
This pair of Wahlberg’s eagles has occupied the same nesting area in central Londolozi for the last 10 years.
It’s usually the Wahlberg’s Eagles and Yellow-Billed Kites that are the first to arrive here, but this year we’ve seen a slight change up with Lesser Striped Swallows, Greenshanks and some Sandpipers already being recorded. Maybe they’re also starting their migrations early.
The cuckoos will still take a couple of months to get here, but given their unbelievable cross-Sahara prowess, maybe we should expect some of them next week…
Definitely going to have a look at the website. I can’t wait for the migrants to arrive each year. Is it early for the Walbergs?
Unbelievable migratory pattern–thanks!
James, I love birds. Like you, I would love to follow the migration of the cuckoos. Please keep us posted.
So you are saying that the tracks shown in the map are simply the beginning of a greater cuckoo migration all the way to the Cape? Wow! Another amazing migration story!!! Thank you!
Hi Guys,
Interestingly enough, none of the cuckoos in this study seem to have made it all the way down to South Africa. It seems that the UK individuals only go as far as West and Central Africa. Maybe the ones tht make it to Londolozi start a bit closer, ie. southern Europe. I’ll dig around a bit and see what I can find…
Great article, James. Once again, I am thrilled with the diversity and range of your thought.
James, absolutely fascinating. I’ve read articles and watched documentaries on the migration patterns of other birds and it’s amazing how many survive their brutal journeys.
Good luck with following your cuckoos!!
The Cuckoo (common cuckoo), arrives at our farm in Co. Kerry, Ireland on April 25th. This is a give or take ETA, but he is remarkably consistent. Its lovely hear the first cuckoo on a fine spring morning, and its also lovely to hear the the silence when he’s gone. His favourite perch is just a few meters from our bedroom window and he rises at first light, around 4am. So we are happy to see him go by the 1st July (much earlier this year).
We still have reasonable numbers of cuckoo (I often see competing males), but yes they are declining. However, the decline is more notable amongst our earlier arrivals, the swallow (Barn Swallow), who normally and very consistently arrives two weeks before the cuckoo. This year there were no swallows in April, apart from one or two transients. Of the six or eight pairs that normally nest in our various outbuildings only two pairs eventually arrived, very late in May, and then they only raised one brood. Whereas we would normally see them until well into September, they are already departing for warmer climates. Look after them well down south, we need more numbers back next year!
I very much enjoyed your response and the information shared about the migratory birds in your country, Alan. Thanks!
Thanks Joanne, I did get one thing wrong. The cuckoo only stays with us for 6 weeks and is usually gone by early June (Not July). I have been writing about the swallow migration in Europe all summer and eventually have some response from Birdwatch Ireland. They believe that storms in Southern Europe during Spring have impacted this years migration, causing a drastic reduction in numbers reaching us.
Bird migration has always fascinated me and I am amazed at the tenacity these little creatures have. Jaw dropping trip across the Sahara!! Unbelievable!