Sunday, 31 May 2015

A costly way of thinking

Flight is a very costly activity indeed. Birds spend a great deal of energy lifting off and staying in the air. Long distance migrants, like our Terns, direct so much energy towards flying that they must reduce the energetic demands elsewhere in their bodies. One way in which birds have reduced energetic expenditure is in the brain. For many regular and day-to-day behaviours, birds operate on a “rule of thumb” basis. They essentially skip the thinking part by following the simple rule “if such-and-such a situation is happening, then… do this”. For example “if there are white speckled things in my nest, then…sit on them” soon followed by “if there are cheeping, gaping things in my nest, then…feed them”. Following this rule of thumb, birds will incubate their young as eggs and then feed them as chicks. By using this method of thinking, the brain does not need to be as big and complex and more energy can be directed to activities like flying.

But alas, although they evolved to work very well and save a great deal of brain power, sometimes a rule of thumb behaviour just ends up wasting your time. For example, see the case of the Black-headed Cardinal feeding goldfish in a garden pond. Following the rule “if I see a red coloured, gaping hole, then…feed it”, the Cardinal's brain is triggered by the shape and colour of the goldfish mouths and, thinking they are actually the gaping mouths of baby chicks, feeds the fish as if they were its own young in the nest.

I saw a similar example of time wasting in the colony today during a rowdy encounter between the Little Terns and Ringed Plover. To explain it, I must first explain two rules that Little Terns and Ringed Plover follow.

Rule #1: “If there is a sick individual attracting attention to the colony, then…chase it away” – Little Terns.

Nesting in groups helps protect Little Tern nests from predators. When a big black crow flies into the colony (or when I go in for colony nest checks), the Terns get together and torment it until it retreats. Similarly, the Terns get together in a gang to chase away any sick individuals near their nests. Sick individuals are loud and flap about, creating a landing beacon for any hungry predators lurking nearby. If there is a sick bird flapping and crying in the colony, the Terns will mob it until it either leaves, or in grim circumstances, gives up and dies.

Rule #2: “If a predator is near my nest, then…attract its attention to me instead” – Ringed Plovers.

A strategy often used by ground nesting birds, when a predator is near the nest, the parent attract its attention and leads them away from the nest. Birds do this by pretending to be sick or injured – an easy catch and an easy meal for a hungry fox. When I approach a Ringed Plover nest to do my colony nest checks, the Plover whistles and cries out to me, then pathetically limps the opposite direction waggling a “broken” wing falling all over the place. It is effective – I do get very distracted! Predators will follow the “injured” Plover away from the nest a sufficient distance before she miraculously heals and flies off into the distance.

Maybe you can already see where I am going here. This morning in the colony, a Plover, sensing some sort of predator danger, began her broken wing exercise to protect her nest. The Terns, on seeing this sick and injured individual near their nests, began to mob and harass her. The Plover felt more threatened and upped her limping and squealing antics. The Terns became more concerned and upped the shouting and dive-bombing. The scene escalated to a tight cluster of 30 Terns furiously screaming over the head of a single Plover rolling around on the ground having an epileptic fit.

Nobody was incubating their eggs. Nobody was fishing for food. Yet there were no predators in sight and no dying birds to attract them. Following their rule of thumb, while usually quite beneficial, just didn't really do the job this morning. The Terns eventually dispersed and returned to a state of peaceful incubation with their Plover colony-mates.

There you have it, you can never be prepared for everything.

Susan and Paddy

Wednesday, 27 May 2015

Kilcoole hits double figures!

After the joyous occasion of finally finding the second nest, they just kept on coming! In the past three days, we have shot up from 1 to 18 nests -the season has truly taken off! Many of the nests have one egg, but are likely to add more to their clutch. Two ambitious Terns even have nests of three eggs.

Nest No.9 - a two egg clutch

With the cold wind and rain today, I made the executive decision not to enter the colony so the Terns could stay warming their eggs as much as possible. Much of the afternoon was spent in amusement watching Tern antics from the shelter of the bird-hide. For a bird so elegant in flight that they are nicknamed “swallows of the sea”, the Little Terns really lose their grace down on the shingle. They trip and fall trying to cross the stones on their short little legs, shakily holding out their wings for balance. Of course, when your bill is as long as your face it, is very difficult to look down and see how high you need to lift your little feet, so more than one Tern has ended up sprawled over the stones. Surprised, they scramble up, fold up their wings like nothing just happened, and preserver. Each time they slip and wobble, I wonder why they don’t just take to the air in graceful flight. Perhaps we can take a little something from their determination.

The hide doubles as watchtower and rain shelter

The courting behaviour observed the past week continues. Plenty of male Terns are landing with impressive and tasty fish to present as gifts to their prospective mates. This allows the female to judge whether her chicks will be well provided for: the more fish he can bring her, the more certain she can be of his hunting prowess and capabilities. Single-motherhood for a Tern would prove nearly impossible when she has to be incubating eggs on the shore and hunting sandeels at sea all at the same time. Extensive days of courtship cumulate in a little dancing ritual where the Terns turn their heads from side to side, the male still brandishing a fish, while the female crouches in her freshly dug scrape. After mating, the male waddles around his new mate in a few excited victory laps (until tripping over a pebble, as outlined above).

Young life has come to Kilcoole already…but not on the beach. A Mute Swan with one fluffy cygnet was swimming in the lagoon behind the colony yesterday afternoon, and a Mallard with ducklings last week. We are still waiting for the Ringed Plover and Oystercatcher breeding within the colony to hatch out something cute and fluffy. Some day soon.

Susan and Paddy

Monday, 25 May 2015

Egging on the Terns

After finding our first nest, we had a four day wait until finally, while telescoping out of the hide this morning, I saw a Little Tern carefully turning her eggs in the scrape before settling back to incubate. A short time later, her mate landed beside the nest with a sand eel that she gratefully snatched off him and swallowed. Little Terns will catch and carry back food to their incubating mates, a strategy that ensures the eggs are protected for as much time as possible. They will also take turns incubating the eggs, so either male or female might be sitting on the nest. A fair trade!

On seeing the Terns feeding each other, I knew to search for a nest and discovered a single egg. It is likely another egg, or perhaps even two more, will be laid by tomorrow. By the end of the day, we had found three nests, with an egg apiece, bringing us to a total of four nests and five eggs. Plenty more can be expected if the number of successful courtships this morning is anything to go by! A large number of Terns are digging out scrapes for nesting and sampling the shingle for good nesting sites. They are also becoming very defensive of their little territories – all sure signs for breeding.

The shore in Kilcoole supports many bird species along with the Terns. Ringed Plover and Oystercatcher are also breeding within the colony, while Whimbrel and Dunlin feed on the foreshore among the Terns. Last night, we were excited to have Declan Manley down to Kilcoole to ring Dunlin in the lagoon behind the colony. He set four nets in the lagoon during low tide hours and waited for the rising tide to push the waders into our nets. Just before dark, we had a successful catch, including this youngster, who is still too young to produce the breeding plumage worn by adults in the summer season.

One of Kilcoole's own Dunlin (S. Doyle)
More to come,
Susan and Paddy

Friday, 22 May 2015

Egg-citing news for Kilcoole!

After a week of hopeful waiting and scanning the shingle with our telescopes, our patience was rewarded yesterday. Just before dark, we spotted a Little Tern sitting among the stones while all the other Terns had gone to roost. She was sitting on two eggs, so we are delighted to announce our first Little Tern nest for the 2015 season!
Little Terns lay their eggs in shallow scrapes directly onto the shingle © Chris Dobson (picture taken under NPWS licence)

Last year’s Terns began laying on the 25th of May due to very bad weather the week before. This year, the first nest was laid on the 21st of May, four days earlier. However, even four days earlier, the Terns began nesting later than expected. Perhaps this is due to last week’s gale winds and heavy rain.

We have not come across a second nest since last night, but judging by the courting activity and the large number of Terns, we are expecting lots more! Our largest colony count this week was in and around 200 Terns. Hopefully many of these will choose to stay and nest in Kilcoole.  

Susan and Paddy

Monday, 18 May 2015

A colour-ring 'terns' up in Kilcoole!

Yesterday I spotted a Little Tern on the shingle with colour rings on its legs. It had a metal ring on the right leg and a yellow ring on the left. This colour combination is likely to be on a Tern ringed in the Isle of Man, where there are breeding Little Tern colonies on the Ayres to the north of the island. While I didn’t get a chance to read the inscription, hopefully I will get another chance in the coming days and we can find out more on this bird’s history.

Numbers of Terns are on the rise. Plenty of courting behaviour was observed  between showers today - see this photo of a male presenting his courtship gift to a discerning female. Other males have successfully wooed a mate and are prospecting potential abodes for their youngsters around the shingle.

Young love © Chris Dobson 

Although no Terns have laid eggs, the Ringed Plover and Oystercatcher are well on their way to parenthood. Three pairs of both Ringed Plover and  Oystercatcher have made the colony home and are already incubating eggs. Territory disputes are flaring up between the species – with plenty of panicky Ring Plovers valiantly defending their nests!

Protective parents © Chris Dobson
Susan and Paddy

Sunday, 17 May 2015

A new season. A new hope.

The 2015 Kilcoole Little Tern Conservation Scheme season began May 11th with the arrival of the wardens and fenceposts. Just 30 Little Terns were waiting to greet us, but this number has slowly risen over the past week thanks to a strong southerly wind carrying Terns with it from Africa.

2014’s wardens, Andrew and Darren are continuing in their ornithological ways. Andrew has left the Little Terns to care for their Roseate cousins on Rockabil (terncoat!). You can keep up with his decent into madness on the Rockablog Darren has journeyed overseas to the sunny islands of Indonesia to study the island biogeography of Sunbirds, White-eyes, Flowerpeckers and probably some more, for his PhD in TCD. We wish them both the very best in their endeavours! 

Night warden Cole Macey will be with us for his 8th season in Kilcoole and will hopefully bring the luck of last season back with him. The new day wardening team for 2015 are Susan Doyle and Paddy Manley - see more about us on "meet the team". East Coast Nature Reserve warden Jerry Wray will once again act as reserve warden, providing much needed cover and help putting the colony set up in place. Dr. Steve Newton of BirdWatch Ireland manages the Kilcoole project, as part of his hectic seabird schedule!

As per usual, the colony fence is put up once Little Terns show up in Kilcoole. We made great progress, getting both the fence and the bird hide up in just a matter of days thanks to the help of Chris, Declan and Cillian. Hopefully, Little Terns will take up residence in their shingle estate in the next week or so. 

Tern Wardens - Jerry, Paddy, Susan and co. © Chris Dobson
Last years first nest was discovered on May 25th because bad weather delayed the Terns. Heavy rain and wind last week may cause the same situation this year. However, we have already marked two Ringed Plover and one Oystercatcher nest within the colony!

Susan and Paddy

Tuesday, 5 May 2015

Nest moving Terns dodge high tides

They’re back! The first Little Terns returned to Ireland last month and the first Little Tern was seen back in Kilcoole on the 19th of April. It won’t be long before the wardens are back on site, the fences are up and the beautiful Little Terns start nesting again. Let’s hope that we have another bumper year in Kilcoole after last year’s record breaking season.

They're back! © Andrew Power and Peter Cutler (Picture taken under NPWS  licence) 

The return of the Little Terns has also been marked by the publication of a paper by the 2014 Kilcoole team in the latest issue of IrishBirds based on observations we took of a unique response by the Kilcoole Little Terns to a dangerous high tide. While we do everything in our power to protect the Little Terns in Kilcoole, some things are out of our control. A high spring tide allied with a strong easterly wind has the power to wash out an entire colony. This happened in 2012 at Kilcoole, destroying every nest. The terns that year didn't stand a chance as the tides were just too strong. The bad weather meant that 2012 was a particularly bad season for terns in Britain and Ireland but, luckily, terns can bounce back quickly when conditions are suitable (just look at the success of last year). Although high tides are an ever present danger to Little Tern colonies, last season the Little Terns showed us they are not completely helpless to the forces of nature.

Spring tides last year © Andrew Power

Last year high tides hit the colony during the peak of the breeding season. When the tide receded and we wardens could survey the damage, we feared the worst, with the seaweed line having been thrown over a large section of nests. Confirming these fears 12 nests had been completely washed away. However, to our surprise, 13 pairs of terns had managed to re-gather and move their clutches into new nest scrapes further up the beach after inundation by the tide. Though the movement of eggs into new nests has been observed in waders and waterfowl, most notably in the Piping Plover, this behaviour has never previously been recorded in a tern species.
We closely observed the outcome in these nests and unsurprisingly found that a significantly higher proportion of eggs from tide affected nests failed to hatch than from nests that were unaffected by the tide. The chill of the Irish Sea coupled with the mechanical damage caused by tide inundation were likely to have been (literally) a killer combination for the developing embryos within the eggs. However the 13 Little Tern pairs which had nests inundated by the tide still managed to produce 20 fledglings (out of 32 eggs in these nests). This was a remarkable achievement given the circumstances, attesting to the robustness of the tern eggs and adaptability of the parent birds, key attributes when living in an unpredictable environment.
We also observed this behavior from a pair of Ringed Plover earlier in the year. Unfortunately the eggs did not hatch but they gave themselves a fighting chance. That combined with the hard work of the wardens and volunteers will hopefully ensure a bright future for the birds in Kilcoole.

The original nest scrape is on the left and the 4 eggs moved by the parents can be seen on the right © Andrew Power

Blog post by
Andrew Power and Darren O'Connell