What to Spot May 2017 May is one of my favourite months in the year, when every time you turn your back, something else comes in to flower or starts flying or singing and I panic that I’ll miss something! Listening to the dawn chorus is a particularly joyous experience and well worth the pain of an early start. I heard the first tentative stirrings of birdsong at the barrage from our resident song thrushes way back in January but now that the resident songsters such as robins, blackbirds and song thrushes are joined by the warblers including blackcaps, willow warblers and chiffchaffs, it can be difficult to separate out the individual species from the general cacophony. There are a number of theories behind to explain dawn chorus including the fact that the light isn’t good enough for foraging so male birds make the most of this opportunity to advertise their presence, keeping rivals away and attracting potential mates. You have to an extremely early riser to hear the dawn chorus start up as the first birds to give voice (often blackbirds) start before dawn breaks. I’m afraid I’m not as keen on that experience as I once was and so our Dawn Chorus on May 7th at the Tees Barrage is at the slightly more civilised time of 5am which is still early enough to make it feel special. May is also a time of change in the river itself, when we see one of our most intriguing and enigmatic fish return to fresh water after a truly epic migration across the Atlantic Ocean from the Sargasso Sea, near the Caribbean. Once found and caught in abundance, the eel is now is serious decline across Europe for reasons that are still unclear. It’s hardly surprising as their life cycle is incredibly complex and human influences both on rivers and across the oceans must be having an impact. A couple of years ago, the Tees Rivers Trust helped us show a group of children from Hardwick Green Academy the typical size of elvers or young eels that were moving back up the river via the fish pass at the Tees Barrage. The children were particularly impressed with the thought that these small and frail looking fish had travelled over 3000 km to reach the Tees, using ocean currents to aid their crossing and changing colour and biochemistry as they nosed their way up estuaries and in to fresh water. They settle in the Tees and its tributaries to mature for up to 15 years as yellow eels and after which they make the reverse journey, back down to the sea as silver eels and then across the Atlantic to spawn in the Sargasso Sea and die and the cycle starts again. A long distance traveller indeed that deserves our admiration and help.