North American songbird southward migration, new research


This video from the USA is called Act for Songbirds – Help Save Threatened Migratory Birds.

From the Journal of Field Ornithology in Canada:

Connecting breeding and wintering grounds of Neotropical migrant songbirds using stable hydrogen isotopes: a call for an isotopic atlas of migratory connectivity

Volume 85, Issue 3, pages 237–257, September 2014

ABSTRACT

There is an overdue and urgent need to establish patterns of migratory connectivity linking breeding grounds, stopover sites, and wintering grounds of migratory birds. Such information allows more effective application of conservation efforts by applying focused actions along movement trajectories at the population level. Stable isotope methods, especially those using stable hydrogen isotope abundance in feathers (δ2Hf) combined with Bayesian assignment techniques incorporating prior information such as relative abundance of breeding birds, now provide a fast and reliable means of establishing migratory connectivity, especially for Neotropical migrants that breed in North America and molt prior to fall migration.

Here we demonstrate how opportunistic sampling of feathers of 30 species of wintering birds in Cuba, Venezuela, Guatemala, Puerto Rico, and Mexico, regions that have typically been poorly sampled for estimating migratory connectivity, can be assigned to breeding areas in North America through both advanced spatial assignment to probability surfaces and through simpler map lookup approaches. Incorporating relative abundance information from the North American Breeding Bird Survey in our Bayesian assignment models generally resulted in a reduction in potential assignment areas on breeding grounds.

However, additional tools to constrain longitude such as DNA markers or other isotopes would be desirable for establishing breeding or molt origins of species with broad longitudinal distributions. The isotope approach could act as a rapid means of establishing basic patterns of migratory connectivity across numerous species and populations.

We propose a large-scale coordinated sampling effort on the wintering grounds to establish an isotopic atlas of migratory connectivity for North American Neotropical migrants and suggest that isotopic variance be considered as a valuable metric to quantify migratory connectivity. This initiative could then act as a strategic template to guide further efforts involving stable isotopes, light-sensitive geolocators, and other technologies.

American tanagers’ colours and songs, new study


This video is called Colombia Tanagers [various species].

From Wildlife Extra:

Study dispels Darwin’s theory to prove birds can have it all

Despite popular belief birds can have a brilliant plumage, a virtuosic singing chirp and an intricate dance routine say scientists.

The author of a new study, Nick Mason, from the the Cornell Lab of Ornithology in New York state, challenged the long-held notion, first proposed by Charles Darwin, that for a bird species to excel in one area it must give up its edge in another.

For example, male northern cardinals are a dazzling scarlet, but sing a fairly simple whistle, whereas the dull brown House Wren sings one of the most complicated songs in nature.

Mason and his colleagues tested the theory by examining a very large family of songbirds from Central and South America, the tanagers.

This group consists of 371 species and included some of the most spectacularly colourful birds in the world such as the paradise tanager as well as the more drab birds, such the black-bellied seedeater. The group also includes both accomplished and weak songsters alike.

“If there were going to be any group of birds at all that would show this trade-off, the tanagers would be a very good candidate, because there’s all this variation in song and plumage complexity,” Mason said.

“But when we dived into it and did some rigorous statistics, it turns out that there is no overall trend. Tanagers can be drab and plain-sounding, or colourful and musical, or or anything in between.”

It’s still possible that trade-offs take place at the level of genus, Mason said, or that they influence species relatively fleetingly as evolutionary pressures appear and disappear.

But as a broad effect on an entire family of birds, a voice–plumage trade off doesn’t seem to exist. One possibility is that the resources needed to develop fancy plumage are different from the ones required for complex songs, freeing tanagers to invest in both forms of showiness simultaneously.

United States songbirds migrate with the wind, new study


This video from Canada says about itself:

Indigo bunting, Blackburnian warbler, stop on migration at my bird feeder

14 May 2013

My first sighting of Indigo bunting, Blackburnian Warbler, photos and video on their way North, Woodslee, Ontario.

From Wildlife Extra:

US songbirds are found to migrate with the wind

Millions of tiny songbirds, many weighing less than an ounce, migrate thousands of miles from North America to Central and South America each year. How they do it has been somewhat of a mystery, but now scientists have discovered how far they take advantage of prevailing wind patterns to save calories.

“Most of what we’ve known about migration routes comes from ducks and geese,” said Frank La Sorte, a Cornell Lab of Ornithology research associate and lead author of the paper in the Journal of Biogeography. “But terrestrial birds are much smaller and they aren’t reliant on the same kinds of habitats. There really isn’t a narrow migration path for them, and they aren’t necessarily in the same place in spring and fall.”

The findings from this study are important as they may help refine ideas about how and where to plan for conservation along migratory pathways.

“All these species migrate at night, at high altitudes, where we can’t see them,” La Sorte said. “But when the sun comes up in the morning they have to find somewhere to land. So any new knowledge about where they’re travelling is valuable to conservation planners.”

For years US scientists assumed songbirds followed the same well-defined “flyways” that ducks, geese, and shorebirds used to travel up and down the continent. There is one known wildfowl flyway along each coast, one up the Mississippi River valley, and one in the centre of the country. Those flyways were marked out from studies which compiled data from recoveries of birds with leg rings and records kept by hunters, but those methods don’t work for small songbirds that migrate at night.

The new work solved this problem with a fresh approach using crowd-sourced data submitted to the Cornell Lab’s eBird project between 2004 and 2011. The researchers analysed thousands of people’s sightings to develop, for each of 93 species, an aggregate picture of where a species is during spring and autumn migration. Although they weren’t tracking individual birds, collective sightings gave them an indication of how the species were migrating. They then used computer models to sort species with similar movement patterns into groups and compared migration routes with seasonal patterns of prevailing winds at night.

The study revealed that most US land birds fit into three main groups: a western one of 31 species, a central group of 17 species, and an eastern of 45 species. Examples of each group include the black-throated gray warbler, the clay-coloured sparrow, and the American redstart, respectively. The researchers noted that the flyways for these are much more spread out across the continent than those of wildfowl, and routes in the central and eastern groups overlap considerably.

The analysis also revealed that many more land birds than previously realised follow different routes through America in spring and autumn — particularly in the East, where many species cross the Gulf of Mexico in a single overnight flight.

Unlike wildfowl, which migrate north and south along the same relatively narrow routes, rather like lorries on a motorway, songbirds are more like passenger cars touring back roads. They are less tied to a single wetland habitat, so they can fan out. By shifting routes, birds take advantage of stronger tailwinds in spring and less severe headwinds in autumn. Tailwinds represent a huge advantage for small birds heading north to their breeding grounds, while finding weaker headwinds allows southbound birds to make the best of a bad situation.

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South American giant rodent on English golf course


This video from England says about itself:

World’s biggest rodent caught on UK golf course

5 May 2014

A bunch of golfers have recorded footage of the world’s biggest rodent, a Capybara, running loose on a UK golf course, a long way away from its usual home in South America.

World’s biggest rodent seen on loose on Essex golf course

Golf players film a 4ft long rodent usually found in South America sniffing around their course in Essex

First there was the runaway rhea seen roaming a Hertfordshire golf course. Now, it seems that putting greens and fairways have proved tempting refuge for another animal fugitive: a capybara.

The creature — the world’s largest rodent species — was filmed ambling around near the 8th tee at the North Weald Golf Club in Essex after apparently escaping from a fenced enclosure at nearby Ashlyns Farm Shop.

Like the rhea, the capybara is a native of South America — but unlike the 6ft bird, which is reputedly capable of disembowelling a man with a flick of its claws, the runaway rodent is not believed to be dangerous.

Described by bemused golfers as looking “like a cross between a beaver and a bear”, capybaras are in fact most closely related to the guinea pig, but dwarf them, growing to as long as four feet.

The creature was spotted at the Essex course on March 16 when, according to the club, “golfers approaching the 8th tee stumbled across something that looked quite out of place on the course”.

“Kevin & Barbara Walters and John & Pat Miles were about to play their tee shots when Kevin saw what he thought was a wild boar meandering around the pond. After a quick phone call to the clubhouse, Angus and Hamish arrived at the scene with cameras at the ready to capture the rare sight,” the club said in a statement on its website.

Another club member, Stefan Freeman was “next up on the tee” and identified it as a capybara.

Rob Dixon, manager at Ashlyns Farm Shop, confirmed it was “missing a capybara”.

He said the solitary male animal had been sighted since but attempts to catch it had so far proved unsuccessful. “We keep on trying to catch it, but as soon as we try and catch it, it’s moved on or it jumps in the river and shoots off. Next time we’ve got to get a vet out and try and tranquillise it,” he said.

“They run away from humans — they’re quite shy,” he added. “They’re not like a rat, they’re almost like a big hamster.”

Capybara owners in the UK include Lady McAlpine, who wrote last year that a capybara had gone missing from her Fawley Hill estate in Henley-on-Thames and “gone to swim in the Thames”.

Lady McAlpine, whose capybara has since returned, said that they were “tremendous escapologists”.

See also here.

A South American [rhea] giant bird that has been patrolling the fairways and greens of a golf club in Hertfordshire for the last month has been shot dead and will now be made into gourmet sausages: here.

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Frogs mating, and the bats danger


This video says about itself:

Risky Ripples

23 Jan 2014

When a male túngara frog serenades female frogs from a pond, he creates watery ripples that make him easier to target by rivals and predators such as bats. A túngara frog will stop calling if it sees a bat overhead, but ripples continue moving for several seconds after the call ceases. In the study, published Jan. 23, 2014 in the journal Science, researchers found evidence that bats use echolocation — a natural form of sonar — to detect these ripples and home in on a frog. The discovery sheds light on an ongoing evolutionary arms race between frogs and bats. Video by Wouter Halfwerk.

From The Why Files:

Menacing mating game: Frogs fear bats!

23 January 2014

Like any foolish fellow, the túngara frog lives and loves dangerously. To those in the tropical-bio-biz, it’s old news that this resident of shallow ponds ranging from Venezuela to Central Mexico is prey to frog-eating bats.

That croaking mating call makes a great target for the flying mammals with an appetite for frogs’ legs. But now we hear another reason why life is hard for the feckless frog.

In a study released today, scientists revealed that the croaking frog sends two separate signals to the bats: First, the mating call, which deters competing males while attracting females — and those hungry bats.

But the frogs power their croak by inflating and deflating an enormous air sac, which forms ripples on the pond that survive even after the frog chokes off its croaks after seeing a bat against the night sky

To test the interaction between the bats and frogs, first author Wouter Halfwerk of Leiden University in The Netherlands set up an experiment in Panama, using artificial frogs to simulate the appropriate sound, with or without ripples

Halfwerk and co-author Michael Ryan, professor of zoology at the University of Texas, found that bats would attack in response to the mating call alone, but the attacks increased 36 percent when ripples accompanied the soundtrack.

Frogs croak, and then croak!

This makes life difficult for the frogs, Ryan notes. To reproduce, they must call. “The males can stop calling, but they can’t take these ripples back, so the danger of calling extends for a few seconds. It’s amazing that bats are able to figure this out.”

The tests were held in darkness, so the bats must have been using their sonar — echolocation — to find the pattern of ripples.

The mating call is primarily to attract females, but it also shouts “Keep away!” to other males, and the competition doubled their “I’m here too!” responses when ripples followed the croaks. “If you look when they are calling, the frogs are spaced out,” Ryan says. “If another male is too close, they start to make aggressive calls, and sometimes they fight; I have seen them kill each other.”

Ryan, who first noticed the frog-bat system as a graduate student in the 1980s studying with bat biologist Merlin Tuttle, notes, “We have known for a long time that the bats can find the frogs.” The new study, however, is the first to show how waves created when the frog sounds off affects bats — and other frogs.

Now that they know that competing males are more responsive when ripples are present, the researchers plan to see how females act with and without ripples.

Live to love, but love to live!

If the bats have “cracked the code” of the frogs behavior, turning a mating move into a death dance, that could be shaping frog behavior. “We know frogs prefer calling under cover, compared to out in the open,” says Ryan. Not only do bats have trouble flying to the sheltered frogs, but they may also have difficulty detecting ripples with echolocation in the brush.

We mused: the frogs, like certain guys we could name, allow mating to trump everything, even mortal danger. “Through the entire animal kingdom — there are exceptions — but most of the attributes that make an animal sexy or beautiful can be very costly. Men die before women in part because testosterone has a negative effect on the immune system.”

Every time an animal communicates, it creates a disturbance in the environment, and that’s especially true for the “look-at-me” mating messages. “The question I have,” Ryan adds, “is how many of these incidental things that we animals do become fodder for another animal that is looking to parasitize, to lay eggs” or grab dinner?

Do some showboating, and a biological big brother may be bugging your channel, Ryan says. “Males have to make themselves more conspicuous to females; to call louder, to wear brighter colors, do fancy dances. But all of this also makes them more conspicuous to predators.”

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Giant armadillo ecology, new discoveries


This video is called In Search of a Giant Armadillo.

From Wildlife Extra:

Giant Armadillos found to be ecosystem engineer

Secretive species gives shelter to other creatures

November 2013: A South American project into the little-known giant armadillo has unearthed the mysterious creature’s role as ecosystem engineers, giving housing and shelter to others.

The species is so enigmatic that the first ever photograph of one was taken just two years ago, with an automated camera trap capturing the first giant armadillo young earlier this year.

Researchers led by Dr Arnaud Desbiez, the Royal Zoological Society of Scotland’s regional coordinator for Latin America, have now discovered the armadillos dig deep burrows which provide new habitats and resources for many other animals. Camera traps in the Brazilian Pantanal have photographed at least 24 different species using their burrows as either a thermal refuge, shelter against predators, feeding ground or resting spot.

Dr Desbiez said: “It’s amazing to see such a secretive species which occurs at such low densities can play such an important role within the ecological community.”