Tuesday, January 31, 2023

Using mirrors to convince birds to nest: experiments at Lehua Island


(Image: Aerial view of Lehua Island, courtesy of DLNR.)

 If you’re lonely, does looking in a mirror help? Probably not, but it may help for seabirds.

One of the tools wildlife biologists use for re-establishing colonies of some seabirds is mirror boxes—structures with multiple mirrors, designed to convince the birds that there are more of them than there really are.

That’s being attempted at Lehua Island, a small tuff cone island off Ni’ihau, where biologists are trying to re-establish several bird species that once nested there.

Those efforts have a chance of working, since rats were declared eradicated from the island in 2021. Rats are believed to have caused the failure of several nesting species on the island, since the rodents eat both eggs and young birds.

Rat predation is significant: “rats (particularly black rats; Rattus rattus) are considered to be a direct cause of the threatened status of at least 75 island-nesting species of seabirds,” wrote the authors of this paper. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0076138

But once the rats are gone, there is the question of how to convince birds to start nesting in a location again. Mirrors are a solution for some bird species.

The mirror technique is not new, and it seems to work. Researchers in California, who were trying to re-establish a colony of common murre found that once they arrived, the birds were far more dense around mirrors than in other parts of the colony. They seem to like being in crowds. 

At Lehua, mirror boxes are one of the techniques being used to try to lure three species of terns back to Lehua: the ʻewaʻewa or Sooty Tern,  pākalakala or Gray-backed Tern, and the hinaokū or Blue-gray Noddy. 

In addition to the mirror boxes, there are speakers broadcasting recordings of tern songs, and decoy birds.

The state Department of Land and Natural Resources reported on the efforts in this press release.

Researchers are using different techniques to try to attract endangered ‘akē’akē or Band-rumped Storm-petrel and ʻuaʻu or Hawaiian petrels to Lehua. For those species artificial nest boxes and recorded bird calls are believed to be more effective.

All these birds are believed to be normally flying in Hawaiian waters, but several may be nesting in colornies on Kaua’I, Ni’ihau and elsewhere that are at risk from predation. Lehua is free of rats, cats, pigs, dogs and most other predators, so it is considered a good spot for colony re-estalbishment.

But it is not entirely predator-free. Researchers in 2019 published a paper that reported introduced barn owls are preying on seabirds there and elsewhere. 

Authors Andre Raine, Megan Vynne and Scott Driskill reported on the impacts of barn owls at nesting sites on Kaua’i, Lehua and at the small island Moku’ae’ae off Kīlauea Point.

The owls, which ironically were introduced to Hawai’i for the purpose of controlling rats, tend to take adult nesting birds of numerous species.

“Owl depredations were recorded of eight seabird species, the most common of which were Wedge-tailed Shearwater Ardenna pacifica, Black Noddy Anous minutus, and Bulwer’s Petrel Bulweria bulwerii. Included were 21 depredations on federally listed Newell’s Shearwater Puffinus newelli and Hawaiian Petrel Pterodroma sandwichensis,” they wrote.

While rats generally went after eggs and young, owls generally take adult birds.

Their recommended solution:: “Barn Owl control should be considered as an integral part of all Hawaiian seabird management programs.”

© Jan TenBruggencate 2023

Sunday, January 29, 2023

Why did the sperm whale die? That's not yet clear, but myriad possibilities

 It will likely be weeks or longer before we know why a big sperm whale washed ashore on Kauai, or we may never know.

Some folks have already been suggesting theories, but without doing the science, it’s guesswork.

There are many known causes of sperm whale strandings—many natural and some involving human activities.

Veterinarians and other wildlife experts are doing the hard work to conduct a necropsy on the more than 50-foot sperm whale that washed up at Lydgate Beach Park in Wailua, Kaua’i, on the morning of January 28.

But let’s look at some of the possibilities.

Whales do get old and die. They get viruses and other diseases. They can be affected by parasites. There is some evidence that climate change can impact navigation and food availability. They can be injured by natural (think big sharks) or human (think container ship impacts) causes. Noise can disorient them, and that noise can be from natural causes like undersea earthquakes, or human causes like deep sea mining exploration, sonar and noisy big ships.

The options really are too numerous for guesses to be taken seriously. Some recent strandings have had various causes.

One sperm whale that beached in the Florida Keys last year was very thin. On investigation, it had ingested marine debris, which had interfered with its ability to feed.

A 30-foot sperm whale that washed up this month in Oregon had injuries consistent with being hit by a ship.

This 2018 study suggests that some North Sea strandings may simply have been because the healthy but young sperm whales inadvertently swam into shallow water and couldn’t get back into the deep. 

Sperm whales, like many others, can become engangled in marine debris like ropes and buoys, and can be weakened by having to drag all that weight. Entanglement in fishing gear like buoys can make it difficult for whales to submerge for feeding.

This 2005 study and this 2009 study suggested that sunspot activity and even changes in the Earth’s magnetic field could impact sperm whale stranding. 

As we reported recently at Raising Islands, roughly half of recent stranded whales of various were associated with a newly described virus. 

In some cases, there are multiple things going on, such as skin disease, liver disease, parasites, viral infections, bacterial infections, fungal infections, high concentrations in blubber of man-made chemicals like pesticides and PCBs, and having ingested plastic while feeding. In many cases, it is not possible to determine which, if any, of these was the cause of the stranding.

And then there is the whole issue of climate change, which can impact marine life in numerous ways, including forcing animals into unfamiliar feeding territories, impacting feeding for juvenile animals, and much more. This Australian study from 2013 suggested: “Reductions in the extent of key habitats, changes in breeding success, a greater incidence of strandings in dugongs and cetaceans, and increased exposure of coastal species to pollutants and pathogens are likely.” 

In one month last year, 17 whales of several different species stranded off Norway. The cause is not known, and as the authors of this paper wrote, “Whale strandings are common globally, although to date there are still many challenges in identifying their cause.” 

© Jan TenBruggencate 2023

Saturday, January 28, 2023

Sperm whale strands on Kaua'i's Lydgate Beach at Wailua

 


An adult sperm whale washed ashore early today (Saturday, January 28, 2023) at Lydgate Park in Wailua, on Kaua’i.

The county issued a press release urging people to stay away from the popular beach park while government agencies respond to the incident.

The marine mammal appeared by initial estimates to be more than 50 feet in length, and could weigh 30-45 tons.

The whale was reported visible on the reef off the beach park Friday afternoon, apparently already dead. By morning it was washing in the shorebreak. Government officials were working to determine how to deal with the animal.

Sometimes dead marine mammals are brought ashore for burial. Sometimes they are towed out to sea. And occasionally, particularly when they are in remote locations, they are left to decompose in place, where they become a major food resource for crabs and other coastal marine life.

However, Kaua’i County’s Lydgate Beach Park is hardly a remote location. It gets hundreds of visitors daily for its white sand beach, protected swimming area, pavilions, playground, tennis courts and more. The whale carcass was roughly in the middle of the beach fronting the park, about 1,500 feet south of the mouth of Wailua River.

No cause of death has been determined, but National Oceanic and Atmospheric Administration personnel, along with state Department of Land and Natural Resources personnel, will conduct a necropsy to gather evidence.

In a 2017 stranding of five pilot whales at Kalapaki Beach, about six miles south of Lydgate, the animals were removed to a remote island location, where necropsies were conducted before burial of the whales.

Sperm whales are found regularly in the deep waters off the Hawaiian Islands and the rest of the Pacific, and they were a key target of the whaling fleets that operated around the Islands during the early 1800s. There have been sperm whale strandings on several Hawaiian Islands.

In December 2021, an adult sperm whale washed ashore at Pila’a, Kaua’i, about a dozen miles north of Wailua.

Whale strandings and deaths have been linked to disease, parasites, impact injuries from watercraft and other causes, but the cause of many strandings is never determined.

Newsweek earlier this month reported an unusual increase in marine mammal strandings recently, including two sperm whales and seven humpbacks in the North Atlantic since December. 

NOAA Fisheries reports that on average, there are 20 strandings of whales or dolphins in the Hawaiian Islands in any given year. 

Just this week, researchers at the University of Hawai’i and NOAA reported on a newly discovered virus that was found in the tissues of 15 of 30 tested cetaceans that died on beaches in Hawai’i, Samoa, Saipan and at sea. It is not clear that virus was the cause of death in any of these cases, but it has the capacity to cause significant illness in some dolphins and whales. We reported on that in an earlier blog. 

Sperm whales are the largest of the toothed whales, with adults ranging from 40 to 52 feet in length. The Lydgate whale appears to be at the upper end of that range. They can range in weight from 15 to 45 tons, according to NOAA Fisheries.

They are found throughout the world’s oceans, and while their population has increased significantly from the heavy whaling years, they continue to be listed as endangered under the U.S. Endangered Species Act and depleted under the Marine Mammal Protection Act. They are now protected throughout their range.

NOAA estimates that more than 400,000 sperm whales were taken between the start of whaling in 1800 and its end in 1987 in the North Pacific alone, and more in other oceans. 

A study reported last year in Nature estimates that the pre-whaling global population of sperm whales approached 2 million, that it was severely depleted by whaling, and that in 2022, the number had grown back to around 850,000. But the study said those estimates are very uncertain.

© Jan TenBruggencate 2023

Thursday, January 26, 2023

New clues in Hawai'i whale strandings

 


Whale and dolphin strandings are generally fatal to the marine mammals involved, but also traumatize their human cousins who attend them.

Often, researchers have been unable to figure out why the animals appear to commit suicide. Now there’s a hint of a clue.

Two of the pilot whales that stranded (image above) on Kaua’i’s Kalapaki Beach in 2017 suffered from a newly discovered virus that affected multiple organs.

It was October 13, when five pilot whales drove themselves onto the sand at the popular beach outside Lihue, and fronting what is now the Sonesta Kauai resort. People tried pushing the whales back into the sea, but often they swam or washed right back in. More whales from the same pod were herded away from the beach by paddlers and surfers, and appeared to have survived and left the bay.

They were short-finned pilot whales, Globicephala macrorhyncus.

 A new study of necropsy samples from numerous whale and dolphin strandings—on Kaua’i, O’ahu, Molokai, Maui, Hawai’i Island, as well as Saipan and American Samoa—shows that those two Kaua’I animals and many of the other stranded cetaceans were suffering from a newly discovered beaked whale circovirus.

The study was published today (Jan. 26, 2023) in the journal Frontiers in Marine Research. Its authors are Cody Clifton and Kristi West of the University of Hawai’i College of Tropical Agriculture and Human Resources and the university’s Hawai’i Institute of Marine Biology; Ilse Silva-Krott of Hawai’i Institute of Marine Biology; and Michael Marsik of the National Marine Fisheries Service in Pago Pago.

They call the virus an “emergent disease with unknown population impacts.”

The researchers studied archived tissues collected in necropsies of 30 individuals involved in recent Pacific strandings—including from the brain, kidney, liver, lung, spleen and lymph nodes. In many cases, the virus—identified through PCR testing—was found in multiple organs.

The tissues were being stored at the University of Hawai‘i Health and Stranding Laboratory.

“Of the screened individuals, 15 animals tested positive in one or more tissues, with a single striped dolphin (Stenella coeruleoalba) testing positive in all six tissues,” they wrote.

“Brain tissue was the most consistently positive tissue type (69%), followed by lymph tissue (67%) and lung tissue (64%),” they wrote.

It is not clear whether the viral infection caused or was directly related to the strandings, but it is a significant medical issue for marine mammals.

“Infectious diseases pose a major threat to cetaceans and (beaked whale circovirus) may represent an important emerging disease within populations spanning the central, Western, and South Pacific,” the authors wrote.

Different circoviruses are known from pets and wild animals, including birds, and while they may cause minimal health effects, they can sometimes be fatal. They can be associated with tissue inflammation as well a tissue death in organs. They are often associated with difficulty breathing.

And yet, sometimes, animals can be profoundly infected without showing significant symptoms. A false killer whale accidentally caught at sea had the virus in its brain, lungs, liver and lymph nodes, and yet appeared perfectly healthy.

The earliest recognized occurrence of this virus was in a Longman’s beaked whale (Indopacetus pacificus) that stranded on Maui in 2010. The presence of this particular virus was not identified until 10 years after its death. That one was a very sick whale. It was infected with multiple viruses. The authors of the study said multiple infections like this are not uncommon.

And although that Longman’s Beaked whale gave the virus its name, the disease has now been found in 10 other species of marine mammal. And the authors fully expect it to be found in more marine mammals.

A press release on the study is here. 

© Jan TenBruggencate 2023

You live Hawai'i, you live longer

 You live in Hawai’i, you live longer.

This has been the case for a while, and in the latest statistics, the Islands continue to have the highest life expectancy of any state in the U.S. 

If you live here, on average you can expect to live to age 80.7 years, compared to a national average of 76.1. We are the only state with a life expectancy of more than 80.

The online publication The Hill just discovered the news, and wrote about it this week. 

At Raising Islands, we have covered this issue before.

It’s about exercise, the outdoor life, a low rate of smoking and a comparatively low rate of obesity.

Our rate of death from heart disease is the second-lowest in the country, after Minnesota (must be the ice fishing) and just ahead of Massachusetts (the beans?). The highest five states in heart diseases, listing the worst first: Mississsippi, Oklahoma, Alabama, Arkansas and Louisiana. Here’s the data on that. 

We also have the second-lowest cancer death rate, this time just behind Utah and ahead of Colorado. The five worst: Kentucky, West Virginia, Mississippi, Oklahoma, Tennessee. Here are those data. 

We are in the middle of the pack on death from strokes

There are some other factors, too. We like our beer, but deaths from alcohol are far lower than the national average. And our state spends three times per capita the average state’s spending on health care.

The Commonwealth Fund pulled together all the stats in its 2022 Scorecard on State Health System Performance. It found Hawai’i is not just at the top of the longevity list, but way ahead. 

The numbers grew even more disparate during the COVID-19 epidemic, when the number of excess deaths from all causes were less than a fifth in Hawai’i compared to the worst states—110 per 100,000 in the Islands compared to 596 per 100,000 people in Mississippi.

It’s not all great news. If there is one area that needs a lot of help, it is with mental illness. The Commonwealth Fund report found that Hawaii is the worst state in the country for adults with mental illness who did not receive treatment in 2018-2019. Two-thirds of our adults with mental illness did not receive treatment—and the statistics for Hawai’i are getting worse.

© Jan TenBruggencate 2023