Tag Archives: seabirds

Migratory seabird deaths linked to hurricanes

(Duke University 11 may 2017; Photo Ryan Huang)

Stronger and more frequent hurricanes may pose a new threat to the sooty tern, an iconic species of migratory seabird found throughout the Caribbean and Mid-Atlantic, a new Duke University-led study reveals.

The study, published this week in the peer-reviewed open-access journal PeerJ, is the first to map the birds’ annual migratory path and demonstrate how its timing and trajectory place them in the direct path of hurricanes moving into the Caribbean after forming over the Atlantic.

“The route the birds take and that most Atlantic-forming hurricanes take is basically the same, only in reverse,” said Ryan Huang, a doctoral student at Duke’s Nicholas School of the Environment, who led the study. “That means these birds, who are usually very tired from traveling long distances over water without rest, are flying head-on into some of the strongest winds on the planet.”

“This is worrying because we know that as Earth’s climate changes, we expect to see more frequent and powerful hurricanes in the future — meaning that the chances of sooty terns being hit by storms will likely go up,” Huang said.

Hurricane season typically lasts from June to November, with peak activity occurring in August and September.

A new map produced by the research shows that sooty terns leave their breeding colony at Dry Tortugas National Park in the Florida Keys each June as hurricane season starts. They migrate southward and eastward across the Caribbean through summer and early fall, before skirting the northern coast of South America and arriving at their winter habitat off the Atlantic coast of Brazil in November.

Huang and his colleagues charted the migratory path by recording and mapping the dates and locations of all sooty terns banded for study at the Dry Tortugas since the 1950s but found dead elsewhere. They also mapped locational data retrieved from birds that were fitted with satellite-telemetry tracking tags. When they overlaid all this data with maps of hurricane paths from the same period, they discovered a striking correlation.

“While it’s impossible to say just how many of the birds died as a direct result of the hurricanes, we saw a strong relationship between the numbers and locations of bird deaths and the numbers and locations of hurricanes,” said Stuart L. Pimm, the Doris Duke Professor of Conservation Ecology at Duke’s Nicholas School.

“What’s really interesting is that it’s not just the big category 4 and 5 storms that can kill large numbers of birds. A series of smaller, weaker storms may have the same impact as that of a single large, strong storm,” Pimm noted. “In September 1973, Tropical Storm Delia, a small storm in the Gulf of Mexico, killed a lot of birds because they were in the wrong place at the wrong time.”

Although sooty terns are neither rare nor endangered — 80,000 or more of them are estimated to breed in the Dry Tortugas each year — they have long been used by scientists as an indicator species to determine the health of the region’s marine environment.

“If there are changes taking place in the ocean, you’ll see corresponding changes taking place in the health of these tern populations, among other indicator species,” Huang said. “That’s what makes our findings somewhat concerning. If these birds are experiencing negative effects from changing ocean conditions, they are unlikely to be the only species affected.”

Scientists use satellites to count endangered birds from space

Albatros-Galapagos.jpg

(Wiley 4 May 2017; Photo Wikipedia)

Albatrosses, one of the most iconic but also one of the most threatened groups of birds on the planet, are difficult to study in part because they breed on some of the world’s remotest and most inaccessible islands.

Scientists have now shown that the highest resolution satellite imagery is capable of “seeing” these birds from space, allowing researchers to count their numbers on remote islands directly from satellite images without ever having to go there.

This is the first time that satellites have been used to count individual birds from space.

“The great albatross breed in some really remote places, so counting them by traditional methods can be difficult and expensive. Many important colonies of these endangered birds have not been surveyed for decades, so being able to use satellites, which are relatively inexpensive and can take images of anywhere on earth, will be a step-change in how we monitor albatrosses in the future,” said Dr. Peter Fretwell, lead author of the Ibis study.

Seabird parents compensate for struggling partners

(AOS 26 April 2017; Photo: L. Takahashi)

For species where both parents work together to raise their offspring, cooperation is key — it’s as true for birds as it is for us! A new study from The Auk: Ornithological Advances shows how pairs of Common Murres update each other on their condition so that when one partner needs a break, the other can pick up the slack.

Common Murre parents trade duties throughout the day — one stays at the nest while the other leaves to forage, hopefully coming back with a fish for the chick. Because brooding the chick requires much less energy than foraging, staying at the nest is preferable for a bird that’s in poor condition. Linda Takahashi, Anne Storey, and Carolyn Walsh of Newfoundland’s Memorial University, along with Sabina Wilhelm of the Canadian Wildlife Service, studied the “turn-taking ceremony” that parents perform when they switch places. They found that the time they spend preening each other provides a way for the two birds to exchange information about how they’re doing, so that if one is in poor shape the other can compensate.

The researchers observed 16 pairs of murres with chicks on an island off the coast of Newfoundland in summer 2009, recording their behavior when parents switched duties at the nest and capturing the birds to check their body condition. Their results show that these “nest relief” interactions take longer when one partner is especially low in body mass, suggesting that when brooders withhold preening and stall their departure, they’re letting their mates know that they need more time to rest; the returning mate can then compensate by going off to forage again rather than trading places immediately. Similarly, the brooding mate might let a struggling returner take over take over at the nest even if they haven’t brought back a fish.

“We had been doing murre field work for years in Witless Bay studying reproductive and parental behavior, and we became intrigued with the variation that we saw among pairs in their nest relief behaviors,” says Walsh. “Some nest reliefs were short and businesslike, while other nest reliefs seemed to involve a lot of interaction between the mates, and it took a long time for the mates to exchange brooding duty. When Linda Takahashi came to Memorial University as a master’s degree student, we decided that her project should focus on getting the details about this very interesting variation in murre nest relief behaviors.”

“The roles of avian pair members have been much studied in terms of energy investment and food delivery, but we are accustomed to thinking of these problems in terms of evolutionary tradeoffs. The ways in which contributions are actually negotiated within individual pairs has, until recently, been largely overlooked,” according to longtime seabird researcher Tony Gaston of Environment Canada. “Linda Takahashi’s paper addresses this deficiency, and this is a field which promises to open up additional avenues of research on within-pair communication.”

Puffins that stay close to their partner during migration have more chicks

(Dr Annette Fayet, University of Oxford; 7 April 2017)

Puffin pairs that follow similar migration routes breed more successfully the following season, a new Oxford University study has found.

Many long-lived birds, such as swans, albatrosses or indeed, puffins, are known for their long-lived monogamous, ‘soulmate’ pairings. Scientists have long understood that in these species, reproductive performance is influenced by pair bond strength and longevity, with long-established pairs usually better at rearing offspring. However, in species like puffins which have to migrate to distant wintering grounds during the non-breeding season, very little is known about how mates maintain their pair-bond and behave. Do they keep in contact to maintain their relationship? Or do they go their own way and abandon their mate until the following spring?

The new study which features in the April 7th 2017 edition of Marine Ecology Progress Series, focused on whether puffin pairs stayed in contact during the winter months or instead headed off and migrated independently, prioritising their individual health and wellbeing, and whether this had any effect on the pairs’ subsequent breeding success.

Over the course of six years, the team from Oxford’s Department of Zoology, in collaboration with the London Institute of Zoology, used miniature tracking devices called geolocators to track the migratory movements and behaviour of 12 pairs of Atlantic Puffins, breeding on Skomer Island, Pembrokeshire. They assessed if and how much pairs’ migratory strategies were related to their future breeding performance and fitness.

While pair members migrated separately, their routes were notably similar during the first part of the winter. Partners would then follow separate paths at the later end of the season, but synchronised their timings of return to the colony in spring.

A key finding of the study is that pairs which followed more similar migration routes bred earlier and more successfully the following spring, showing that there is a clear benefit for puffins to migrate close to their mates. This proximity may make it easier for pairs to synchronise their return to the colony in spring.

The findings also reveal that while migrating close to its partner is key to a puffin’s reproductive success, there are other factors at play. Female puffins were found to forage more than males, proving critical to their breeding success the following season. Female puffins that foraged more over winter were able to lay eggs earlier and rear pufflings more successfully, most likely because they were in a better pre-breeding condition.

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Why do guillemot chicks leap from the nest before they can fly?

(Aarhus University, Physorg; 24 March 2017)
It looks like a spooky suicide when small, fluffy guillemot chicks leap from the cliffs and fall several hundred metres towards the sea – long before they are fully fledged. But researchers have now discovered that there is good reason behind this seeming madness.

And you ask yourself why when you on a calm Arctic night watch the spectacular sight of dozens of young guillemots who leave their safe nests and flutter past the towering cliffs into nothingness.

What is it that drives these young birds into something that to the eye seems an impossible survival strategy for the species?

Food deep in the ocean

Researchers from, among others, Aarhus University, Denmark and Greenland Institute of Natural Resources, Greenland, have now discovered that there is good reason behind this seeming madness. They mounted small electronic loggers on the legs of a number of birds and recorded the birds’ flight and diving behaviour in detail.

The guillemot (or thick-billed murre) is a seabird with a long life span. The female lays only one egg and thus has no more than one chick per year. Guillemots nest on cliffs in the Arctic, often in very large colonies with up to hundreds of thousands of birds—including Saunders Island, Thule, Greenland, where researchers have now studied their behaviour.

The arctic summer is short and females must quickly produce an egg. After the chick is hatched and is still in the nest, both the mother and the father bring it food, which consists of small fish.

The small electronic dataloggers revealed that guillemots can dive very deep to find food—down to about 200 m. This is deeper than for any other flying bird.

Males ensure the growth of their offspring

The distance from good fishing spots to the colony may be long, and in late summer the female is exhausted. This is when the male steps into character and guides his offspring to the sea and the indispensable pantry. And the male stays with his offspring for five to seven weeks at sea.

“Our measurements show that the male feeds the chick twice as much as both parents could if the chick remained in the colony.

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A light of hope for seabirds

albatross.jpg(Francisco González Táboas & Leo Tamini; 21 march 2017)

A new light of hope opened last week for large seabirds when Argentina established the use of measures to prevent its death in fisheries.

The days are not easy in the South Atlantic. Life is hard on the ship. The bad weather, the waves of several meters of height and the constant movement make the tasks of the sailors more difficult. The days, weeks and months away from the families accumulate and make the mainland a very coveted good. However, most of these men – and women – on board love the sea. They love their fish, which give them work and livelihood to live. And they love birds too. The immense and impressive albatrosses and petrels are, along with dolphins and whales, faithful companions of the days on the high seas.

And there are a few times when they have to kill or sacrifice some of these birds, which are caught in the dragging cables of the nets. In fact they are many. It is estimated that every year between 9,000 and 18,000 black-browed albatrosses Thalassarche melanophrys die on only thirty Argentine freezer vessels fishing for hake.

With the help of the Albatross Task Force Argentina of Aves Argentinas (BirdLife in the country), boat workers have learned to recognize and identify each species: the black-browed mollymawk Thalassarche melanophris, the Daption capense petrel, the Southern giant petrel Macronectes giganteus, the white capped albatross Thalassarche cauta, the Southern royal albatros of the south Diomedea epomophora and, of course, the king of the seas, the wandering albatross Diomedea exulans, among others, are part of the varied avifauna of those icy Seas.

Each death of one of them hurts. However they have also learned that things can be done to prevent these birds from dying while fishing.…..

Read more in spanish

Seabirds encounter natural changes in the ocean environment

Ancient Murrelets. Credit: Daniel Donnecke

(Spike Millington; March 13, 2017)

Seabirds encounter natural changes in the ocean environment, such as El Nino events that can affect the currents and bring warm or cold water, which in turn affect the distribution and abundance of prey species, such as fish and squid. However, the risk with global climate change is that such events become less predictable and possibly more regular, so that ability of seabird species to adapt can be affected, both in the short-term and long-term. This massive die-off of Common Murres (Guillemots) was due to unusually warm water temperatures affecting the birds’ food supply. If good conditions return, the seabirds can perhaps compensate with good breeding success and numbers can recover in the short-term. In the long-term however, the impacts of climate change-induced conditions are far from certain, requiring long-term monitoring to be able to assess patterns of response.