Little Terns roosting on rocky beach at Baltray, Co. Louth. Image: Jen Lynch (digiscoped).

Over the past week, we have been monitoring the numbers of terns “holidaying” at Baltray. At low tide when the sand is exposed, the terns are spread out across the beach in small groups, along the water’s edge. The rising tide causes the terns to gather together, making them easier to observe, count and to search for colour-rings. It appears there are at least two places that the terns prefer to wait out the high tide. Thankfully both of these hot spots are close to the viewing platform. Choice of roost site seems to depend on a number of factors including the presence (or absence) of other birds (Cormorant, Herring Gulls and Great Black-backed Gulls), disturbance (e.g. people with dogs) and the height of the tide (at higher tides some roosts are covered and birds are forced to use an alternative).

The two main main roost sites used by Little Terns terns at Baltray (bottom) and the Sandwich tern “nursery” next to the shipwreck (top). Image: Google.

At high tide we have regularly counted ~50 Little Terns roosting close to the colony, with varying numbers of juveniles at different stages of development. Today (18th July) there were 46 Little Terns roosting at the southern end of the colony area, including 11 juveniles, with some very “new” looking birds.  At least 6 Little Terns were colour-ringed and it was possible to read some of the inscriptions. “IVD” (green darvic with white inscription on left leg) is still around (ringed as a chick in Kilcoole, Co. Wicklow in July 2015) and he appears to have brought a few friends with him (more info to follow). The Little Terns were joined by a mixed group of larger tern species including Common and Arctic Terns (see Dublin Bay Birds blog) and a single Roseate Tern (see Rockabill blog here). Periodically 4-5 Sandwich terns would fly over (bringing the species count up to 5!), making noise but didn’t settle to roost with the other smaller terns – I wonder where they are roosting?

Sandwich Tern “nursery” at Baltray. Image: Jen Lynch (digiscoped)

At low tide it can be difficult to locate the terns on the beach. However if you take a walk past the northern end of the colony, towards the shipwreck, keep an eye out for the Sandwich Tern “nursery”. On the 15th of July there were 110 Sandwich terns in what appeared to be a nursery area (joined by a small number of Common & Arctic Terns). Almost half of the birds were juveniles (54 juveniles and 56 adults). The adult Sandwich Terns were delivering food non-stop to the hungry mouths, with deliveries arriving across the sand dunes, from the outer part of the mouth of the river Boyne. Among the group, there were 2 juvenile Sandwich Terns with yellow colour-rings. Despite the stiff breeze and falling light, we managed to make out one inscription. Tony Murrary (NPWS) was later able to tell me that “KKB” was ringed as a chick on Inish, Lady’s Island Lake, Co. Wexford on the 21st of June and this is the first time it has been re-sighted. This means that this bird has traveled over 170 km in 24 days, in the first 2 months of it’s life!

Juvenile Sandwich Tern (Yellow – KKB) ringed as a chick on the 21st of June 2017 in Wexford (red) and re-sighted on the 15th of July at Baltray (blue) 24 days later. Image: Google.