Taxi-ing onto the runway – Ranger Mel takes a look at the pre-flight preparations our ducks, geese and waders are undertaking as we head towards spring.

As we Bird Wise rangers approach the end of our seasonal contract we aren’t the only ones getting our house in order. It’s that time of year when the vast array of over-wintering birds begin their circadian countdown to fly back to their Arctic breeding grounds.

Birds are light-sensitive so as spring approaches here in the northern hemisphere, our longer days and shorter nights will be one of the signals for them to begin their pre-flight checks and start carb loading.  In fact you could say that their complete stay here in the relatively warmer climes of the north Kent coastline over winter has been in preparation for them to get back to the northerly latitudes safely and in good enough shape to breed successfully.

Their migratory journeys are long and perilous requiring them to survive storms and turbulence amongst other things. Unsurprisingly then, migration is the highest cause of mortality in adult birds as well as juveniles. Flight is without a doubt the most energetically expensive mode of locomotion and birds don’t fly unless they absolutely have to.  The energy they need to continually operate their flying muscles during long flights comes from the fat reserves acquired here during our winter, especially in the run up to take-off (known as hyperphagia).

They need to have just the right amount of stored lipid fat. Too much will increase their chances of overheating – and weigh them down unnecessarily. Too little will mean they could run out of fuel reserves on the way – with a likelihood of this happening over the ocean. Other physiological changes will also occur before they leave:  changes to their flight muscles and metabolic rates to allow them to deposit fat more efficiently.

Along with their migration routes, these fine checks and balances of fat gain and body changes are inscribed into their genetic evolution over millions of years.

If they make it, the Arctic regions can be bountiful. Not only do predator numbers decrease (in the higher latitudes mammalian predators will mainly be Arctic foxes and the odd polar bear) but…there will also be zero human induced disturbance.  All of which are important factors for the survival of ground nesting birds. The land of the midnight Sun will allow for non-stop foraging and the fresh vegetation growth will not only provide shoots for the herbivorous birds, such as Geese, but habitat for insects to thrive – ready to be eaten by the insectivorous waders.

Closer to home, along the Swale estuary we have had some impressively high bird counts this winter. Regularly occurring birds included about 20 species of wader, 10 species of duck, not to mention the various geese, herons and swans: some of these numbering in the low 1000’s: Brent Geese, Dunlin, Lapwing, Mallard, Oystercatcher, Redshank, Teal and Wigeon.

More than 40% of the world’s bird population are migrants but where exactly are the ones we see on our marshes heading? The dark-bellied Brent Geese will fly back to Siberia – a distance of around 3,800 miles.  Their strong dependence on certain food types makes them more vulnerable than other types of geese. You will recognise them as they fly by in loose V formations making their very distinctive ‘cronking’ call.

Our most numerous small wader is the Dunlin and you may have seen these birds swirling in huge acrobatic flocks, flashing dark and light as they flip in unison. These little birds will fly 800 miles or so back to their Norwegian breeding grounds. No mean feat for such a tiddler.

In the medium sized category we have the Redshanks – known as the “wardens of the marsh” due to their flighty temperament. Some might migrate 400 or so miles within the UK to their breeding grounds in the north of the UK but within any flock you might see, half of them will be from Iceland

The Grey Plovers we see here in winter are not so easy to spot to the untrained eye but, like all plovers, they are ‘visual’ feeders and out of necessity have large eyes and short, stubby beaks.  They also have black armpits which can only be seen in flight or when they are having a stretch. Also from western Siberia, as spring ends they will moult into their smart breeding plumage ready to leave during May.

Lapwing (also a plover), Woodcock and Curlew (our largest European wader) do breed in the UK but winter numbers of each are dramatically swollen by north eastern arrivals during Autumn – and of course these birds will return there to breed. UK estuaries are incredibly important over-wintering sites for Curlews who are globally threatened and on the Red List. These are such beautiful birds – and feature on our Bird Wise logo, being one of our main birds of conservation concern.

Our Kent Turnstones are here in internationally important numbers. They are extremely site faithful to a particular bay or beach throughout their life and very sensitive to human induced disturbance. You probably won’t notice them foraging amongst the beach pebbles as they have excellent camouflage – but keeping your eyes peeled will help you keep your distance. Come spring most will migrate to the Canadian Tundra or Iceland to breed but some passage birds will also arrive here in spring and autumn from the continent.

The stunning black and white Oystercatchers will mainly breed in Norway and Scandinavia but those on the west and north coasts of the UK are likely to be Icelandic breeders. Still, they also breed in the UK and we have heard of an oystercatcher nesting in a coil of rope on the deck of a sailing boat in the Swale estuary! Not least…they are also generally monogamous for their lifetime which was, for one such ringed and re-caught bird, over 40 years.

Many walkers we meet on the Kent marshes tell us they have never seen an Avocet before although within the UK they are quite mobile.  Once extinct in the UK their presence here now is thanks to the RSPB who have worked hard to create their ideal habitat.  They first bred in the UK in 1946 and we can get 2-300 here on our local estuaries. Last year about 16 pairs bred on Sheppey but foxes predated upon most chicks.

Finally, we can’t end without a word about the ducks: our favourite (and smallest) migratory species being the Teal will fly 2500 miles from the High Arctic.  Due to their small size they are very susceptible to unexpected cold snaps but can be here in Kent in high numbers: this winter close to 2,000. The whistling Wigeon will have a 1,500 mile flight back to northern Russia to breed.

So, as you can see, our over-wintering birds really are up against it when it comes to the vast distances they have to fly to get back to their Arctic breeding grounds – and we have only covered just a few species here.  For their very survival it is crucial that, on a daily basis, they are allowed to feed undisturbed and take on the calories they need to maintain their body condition and then, closer to their departure date, make that extra fat gain to use as their migratory flight energy. 

And so, for them and for us, it’s “CABIN CREW……DOORS TO AUTOMATIC”