New Zealand introduced trout eat introduced mice


This video says about itself:

Huge Trout Eats Mice – Wild New Zealand – BBC Earth

19 June 2017

With little competition and few predators, the Brown Trout in New Zealand has been known to grow to epic proportions. These prize fish sometimes reaching a metre in length and weighing up to 5 kilos have developed monstrous appetites and a bloodthirsty penchant for mice.

Cormorants can hear under water, new research


This video says about itself:

HUMAN NOISE DISTURBING MARINE BIRDS

29 May 2017

For the first time a study shows that cormorants can hear under water. This means they can hear – and be disturbed by – human noise: ships, construction work, etc.

From the Rare Bird Alert site:

New discovery: Cormorants can hear under water

20 June 2017

For the first time, researchers have shown that marine birds can hear under water. This offers new possibilities for the protection of marine birds in trafficked waters. Seals, whales and other marine animals can hear under water. The cormorant also has this ability, which new research from University of Southern Denmark (SDU) shows.

According to the biologists it makes good sense that a cormorant can hear under water — the environment where it finds most of its food.

About every tenth bird species — ca. 800 species — in the world hunts under water, and it may turn out that they too can also hear under water.

The sound of fish

Researchers Kirstin Anderson Hansen, Alyssa Maxwell, Ursula Siebert, Ole Næsbye Larsen and Magnus Wahlberg from the Department of Biology at University of Southern Denmark have tested the cormorant Loke’s hearing. Loke lives at SDU’s marine biology research station in the Danish town Kerteminde.

“Hearing under water must be a very useful sense for cormorants. They depend on being able to find food, even if the water is not clear, or if they live in the Arctic regions where it is dark for long periods at a time,” says Kirstin Hansen, Ph.D.

Loke’s hearing abilities are on a par with the hearing of the toothed whale and the seal.

The sound of humans

He can hear sounds ranging between 1 and 4 kHz, and it is in this range that fish such as sculpin and herring produce sounds. Both sculpin and herring are on the cormorant’s menu.

1 — 4 kHz is not only the range in which fish sounds are found. There are also various human-made sounds found in this range.

Human-made sounds can disturb the ocean’s animals to such an extent that they cannot find food or communicate with each other. It is a known problem for porpoises and seals for instance, and now it is also a potential problem for birds. It is certainly something that we should be more aware of, says Magnus Wahlberg, Associate Professor.

Human-made sounds can be everything from spinning wind turbines and ship traffic to water scooters and drilling platforms.

The SDU biologists are now planning more trials, and the next birds to be tested will probably be guillemots and puffins.

Young white coypu video


This 20 June 2017 shows a coypu with its white youngster.

We cannot be sure whether the colour of the young animal is albinism or leucism.

Marianne Leenders made this video in Germany, close to the Dutch border.

Coypus are originally South American rodents, but they are feral in many European countries.

Young spoonbill asks for food


In this 20 June 2017 video, a young spoonbill asks its parent for food.

Herman Schoemaker made this video in the Groene Jonker nature reserve in the Netherlands.

Ants and dead dragonfly


This 20 June 2017 video is about a dragonfly killed by a cat. After its death, the dragonfly attracted many ants.

Eight-year-old Gianni from the Netherlands made this video.

Drowned wildebeest help other Kenyan animals


This video says about itself:

AMAZING FOOTAGE OF WILDEBEEST CROSSING THE MARA RIVER

28 January 2011

They had wanted to cross all day, and by 5-o-clock PM they finally did.

From the Cary Institute of Ecosystem Studies in the USA:

Wildebeest feast: Mass drownings fuel the Mara River ecosystem

June 19, 2017

(Millbrook, NY) Each year, more than a million wildebeest migrate through Africa’s Serengeti Mara Ecosystem. While crossing the Kenyan reach of the Mara River, thousands perish. A new study, published today in the Proceedings of the National Academy of Sciences, is the first to reveal how wildebeest drownings impact the ecology of the iconic river.

Amanda Subalusky, a Postdoctoral Associate at the Cary Institute of Ecosystem Studies, is the paper’s lead author. She conducted the work while a graduate student at Yale University. Subalusky explains, “The Mara River intersects one of the largest overland migrations in the world. During peak migration, the wildebeest cross the Mara River multiple times, sometimes resulting in drownings of hundreds or thousands of wildebeest. Our study is the first to quantify these mass drownings and study how they impact river life.”

The research team conducted five years of field surveys and analyzed a decade of historical reports from the Mara Conservancy to determine the rate and frequency of wildebeest drownings in the Mara River’s Kenyan reach. On average, 6,200 wildebeest – representing 1,100 tons of biomass – succumb each year during migration, with mass drownings occurring in 13 of the last 15 years (2001-2015).

Co-author Emma Rosi, an aquatic ecologist at the Cary Institute, notes, “To put this in perspective, it’s the equivalent of adding ten blue whale carcasses to the moderately-sized Mara River each year. This dramatic subsidy delivers terrestrial nitrogen, phosphorus, and carbon to the river’s food web. First, fish and scavengers feast on soft tissues, then wildebeest bones slowly release nutrients into the system – feeding algae and influencing the food web on decadal scales.”

To reveal the fate of wildebeest carcasses, the researchers modeled in-stream consumption by fish and Nile crocodiles, scavenging by birds, nutrient uptake, and downstream transport. Stable isotope analyses of common fishes, camera monitoring of scavengers, and stable isotope analyses of biofilms (a mix of bacteria, fungi, and algae) on wildebeest bones all informed the fate of wildebeest nutrient inputs.

While wildebeest soft tissue decomposes in 2-10 weeks, their bones persist for upwards of seven years, acting as a long-term source of phosphorus. Rosi explains, “Mass drownings present a striking picture. Rotting animal flesh spikes the aquatic ecosystem with nutrients. But once carcasses disappear, bones – which make up nearly half of biomass inputs – continue to feed the river.”

When wildebeest carcasses were present, they comprised 34-50% of the diet of common fish. The most frequent terrestrial scavengers on carcasses were Marabou storks, white-backed vultures, Rüppell’s vultures, and hooded vultures, consuming 6-9% of soft tissues. Biofilms on wildebeest bones had a distinct isotopic signature, and made up 7-24% of the diet of three common fish species months after drowning events. Due to low metabolic rates, Nile crocodiles were estimated to eat just 2% of total carcass inputs.

Co-author David Post, an aquatic ecologist at Yale University, comments, “The Mara River is one of the last places on Earth left to study how the drowning of large migratory animals influences aquatic ecosystems. Many migratory herds, like bison, quagga, and springbok have been driven to extinction or remnant populations.”

With Subalusky adding, “The migration is currently underway in the Mara, having arrived early this year. What is happening there is window into the past, when large migratory herds were free to roam the landscape, and drownings likely played an important role in rivers throughout the world.”