Sunday, February 27, 2011

There are currently nine accepted records of Frigatebird sp. on the Britain and Ireland list (although some of these refer to the same bird) along with two records of Magnificent Frigatebird and one record of Ascension Frigatebird. With a primarily southwesterly distribution of records it's probably a good idea to gen up on how to nail a Magnificent Frigatebird. Unfortunately frigatebirds can be tough (and sometimes impossible) to identify and chances are that views are going to be a relatively brief flyby (or of something taken into care exhausted). There are five species to contend with, all of which appear similar, but within each species there are a variety of different plumages (It was only in 1914 that it was realised that there are five species rather than two). Indeed frigatebirds are one of the few groups of seabirds that are sexually dimorphic in plumage as well as size. In Costa Rica we had a chance to get to grips with Magnificent Frigatebird.

An adult male Magnificent Frigatebird. Good views but really it's just seperated on range as adult male Ascension Frigatebirds basically look the same and are often considered impossible to seperate in the field. There were no pale brown wingbars above (thus separating male Great Frigatebird) but aberrant male Mag Frigs can also show this feature to complicate things further (c) Richard Brown

An adult female Mag Frig. Lets hope for one of these on Bardsey as we can actually identify this (given such belting views). The black head extends as a well defined V down the white upper breast. The black of the vent forms another V pointing towards that of the throat. There's an indistinct greyish collar, just visible here. The white tips to the axillaries form diagnostic wavy lines on the underwing (c) Richard Brown

A juvenile would also be do-able, assuming that, like this one, the diagnostic white lines on the axillaries had developed. These are retained in females and in males up to subadult stage (c) Richard Brown

But when BBRC are faced with my claim of Magnificent Frigatebird the plot thickens. There are several intermediate phases between the above photos and the amount of overlap with other species is considerable. Ultimately a good photo showing anything between a juvenile with white axillary lines and an adult female might be the only way to get a fly-by accepted.

Friday, February 25, 2011

2011 has started well. Two amazing weeks in Costa Rica and a bit of time catching up with friends and family. We've only seen 118 bird sp. so far but we have bumped into things like Black-necked, Little and Great Crested GrebeBittern, Green-winged Teal, Ring-necked Duck, Smew, Red GrouseBlack Grouse, Avocet, Ruff, Iceland Gull, Water Pipit, Dipper, Marsh Tit, Willow Tit, WaxwingTree Sparrow and Twite, all of which are less than annual or absent from the Bardsey List.

So all this talk of Costa Rica has been a bit of a distraction really as we wait to return to Bardsey. But the weather is changing and Monday is looking good for a crossing. The next two days will be for packing and a pretty major food shop. And then the season begins. Hopefully we'll be blogging most days and if it all goes quiet then there's always more Costa Rica photos to sort through...

Hope it's this flat on Monday, it's always nice to arrive with dry pants (c) Richard Brown
We saw some fantastic raptors, but perhaps the most impressive spectacle was a pair of White Hawk displaying near Arenal Volcano. This stunning species is an uncommon but widespread bird of forested areas.

Four subspecies are recognised. The dark eye and bold black tail markings suggest this is Leucopternis albicollis costaricensis (c) Richard Brown

White Hawks predominantly feed on lizards but also take insects and mammals. They will follow troops of Capuchin Monkeys and Coatis to take any prey flushed by their movements.

A White-nosed Coati busy flushing lizards (c) Richard Brown

Thursday, February 24, 2011

One of the most interesting and frustrating families we encountered in Costa Rica were the Antbirds. Antbirds are a large family of passerines, found across sub-tropical and tropical Central and South America. Over 200 Antbirds are known, of which 22 occur in Costa Rica.

We managed to spot eight of them, though their skulky habits in the dark understory made them quite a challenge. Trying to follow an Antbird sp. through the dark twiggy undergrowth required patience...

A male Barred Antshrike (c) Richard Brown

...but it was well worth it when one of these popped up into a clearing, however brief!

Barred Antshrikes were by far one of the most common Antbirds we encountered on our trip. They are rather widespread, occurring from Mexico through Central America, and into a large part of South America east of the Andes to Argentina, Bolivia and Paraguay. Because of this many sub-species are recognised. This male is of the intermedius race, the only race recognised in Central America.

Antbirds are so called because they have a habit of following ant trails, with arthropods forming the bulk of their diet. But Barred Antshrikes also take seeds and small fruits using their heavy, hooked bills.

The literature describes the Barred Antshrike as ponderous, but this one must have done most of his pondering in private because he didn't stay in one spot for longer than a few seconds.

The Barred Antshrike is sexually dimorphic, the females being rufous-chestnut with a barred head and throat. Both birds are rather cryptic, and perfectly camouflaged in the scrubby understory. This is important, because they share incubation duties. Sexual dimorphism is unusual in birds that share such duties, but it is thought that the male maintains his striking black and white barring in order to defend his territory and attract a mate. Once he has attracted a mate, the monogamous pair will mate for life.

Another fascinating fact about this species, and indeed Antbirds as a whole, is their breeding ecology. Only two eggs are ever laid, and while the parents share the tasks of incubation and feeding of chicks, once the chicks fledge, each parent cares exclusively for one of the chicks. Fantastic! Presumably, this ensures each chick is well fed, increasing the chances of survival.

Wednesday, February 23, 2011

A conspicuous feature of Costa Rican skies are the almost ever-present vultures. We saw three of the four species recorded in the country, with Turkey Vulture and Black Vulture proving incredibly common. The Turkey Vultures were typically low in the sky and often over forest. This is because Turkey Vultures use scent to detect their carrion food. The Black Vultures were more common over open areas and often at high altitude, as would be expected of a scavenger that uses sight to locate food.

The larger Black Vulture will force Turkey Vultures away from carrion if there isn't enough to go around (c) Richard Brown

Turkey Vultures were abundant virtually everywhere we went (c) Giselle Eagle

The only King Vulture we saw during our trip. Whereas the species above are migratory, this species is a resident of tropical lowland forest (c) Richard Brown

There is some debate as to how the King Vulture locates carrion. This individual was very high and was probably on the look out for other vultures showing signs of having detected a meal. But some studies have recorded King Vultures finding carrion in forested areas without the aid of other vultures, perhaps indicative of some olfactory capabilities. 

It is uncertain where the name King Vulture originates but two theories predominate. Excluding the two condors, King Vultures are the largest New World vultures and will displace the smaller vultures from a carcass; they are thus King of the Castle. But the name perhaps originates in Mayan legend where the bird was a king who served as a mediator between humans and the gods.
Butterflies were everywhere in Costa Rica. One of our favourites was a species of Cracker Butterfly, not as bright as a lot of the other butterflies, but amazing for its patterning and ecology.

A Cracker Butterfly. Rather than a chemical defence, these butterflies rely on camouflage. But it doesn't always work, and Rufous-tailed Jacamars have been recorded taking them (also see below for the butterfly-munching habits of the Jacamar) (c) Richard Brown

Cracker Butterflies are named after their curious ability to crack their wings, a sound audible to humans and used by the butterflies in territorial defence and to startle potential predators. It is thought that the sound is created when veins in the forewing meet at a speed of about 1420mm/sec! A neighbouring vein possibly acts as a resonating chamber to increase the volume of the click.

All Cracker Butterflies rest with their heads pointing downwards. They select trees with bark matching their wing colour and then use these trees as courting territories. Males typically perch on between one and four trees daily, from which they click to attract a mate.

Tuesday, February 22, 2011

Motmots are stunning birds of tropical and subtropical forest. There are ten species currently recognised worldwide, six of which are found in Costa Rica. We managed to see four species in our two weeks. Considering that all extant Motmots are in Central and South America, it is interesting that a Motmot-like fossil was found in Switzerland and suggests that they probably arose in the Old World.

A Rufous Motmot at La Selva. Nearly all Motmots have serrated bills, the depth of the serrations relating to the size of insect prey taken. This, the largest Motmot, has very deep teeth on both mandibles. The black spot on the chest is formed by a cluster of elongated black feathers, another feature of a typical Motmot (c) Richard Brown

A Turquoise-browed Motmot showing off another feature of the majority of Motmots, an area of featherless shaft along elongated central tail feathers (c) Richard Brown

Friday, February 18, 2011

There are six species of spoonbill on the planet. In the past I've seen four of them and our trip to Costa Rica added a fifth. The Roseate Spoonbill is the most colourful of the six and is usually placed in a genera separate to the other five species, namely Ajaia. A trip to the far east will be needed to add the final spoonbill, Black-faced Spoonbill.

A Roseate Spoonbill at Palo Verde. The large and sensitive bill is waved from side to side through the water and snaps shut when it touches crustaceans, aquatic insects, frogs and small fish (c) Richard Brown
More of the eleven species of heron we saw in Costa Rica.

Snowy Egrets were abundant at Palo Verde. The extensive yellow backs to the tarsi, coupled with bright yellow lores, will separate it from Little Egret when one rocks up on Bardsey this year (c) Richard Brown

A juvenile Bare-throated Tiger-heron at Palo Verde (c) Richard Brown

A Green Heron, again at Palo Verde, where they were abundant (c) Richard Brown

The only Yellow-crowned Night-herons we saw were along the Tempisque River at Palo Verde (c) Richard Brown

A Tricoloured Heron, probably down from North America for a warmer winter (c) Richard Brown
In massive contrast to the Agami Heron with its long pointed bill, was the Boat-billed Heron with its large boat-shaped bill.

Boat-billed Heron (c) Richard Brown

We found this fantastic looking heron roosting in a tree, with five others, along a trail at Carara National Park. They are inactive during the day and difficult to see. This is because this species is largely nocturnal, searching for prey along waterways at night. 

They have a diverse diet, feeding on fish, mice, water snakes, eggs, crustaceans, insects and small amphibians. 

Check out the size of its massive eye, which must be an adaptation to help it see at night. The massive eye, in conjunction with a massive scoop-like bill, helps this species to catch prey in lower light levels when precise spearing with a long pointed bill (like that of the Agami Heron) would be difficult.
We managed to locate eleven species of heron during our visit, the majority of which were found in open areas of swamp and marsh. But one species was very different. The Agami Heron, a stunning species which gets a genus to itself, was found creeping along a shaded stream deep in Caribbean forest.

An Agami Heron at La Selva. This bird managed to catch two small fish in the ten minutes or so we watched it. The bill is even longer than it looks in this photo! Sadly the Agami loves dark banks under overhanging vegetation which makes photography very hard; this was taken at 1/60sec (c) Richard Brown

Tuesday, February 15, 2011

The best toilet in Costa Rica was this one...

Short-Tailed Bat (c) Richard Brown

We've managed to narrow it down to under the broad umbrella of American Leaf-Nosed Bats, in the sub-family Short-Tailed Bats. In that family it can be one of four species...If anyone knows which one it is I'd sleep better tonight. The presence of warts on its chin (a row of small warts surrounding a large central wart), separates this bat from other sub-families in the Leaf-Nosed Bat family, which incidentally is the largest family of Bats in Costa Rica.

Short-tailed Bats are frugivores, and tend to be specialists of plants of the genus Piper. Pipers are the Pepper Plants, or Pepper Vines. This plant genus also contains a species of pepper that was used by the Aztecs to spice the first Cocoa drinks in Mexico. Its funny to think that the Short-Tailed Bat was partially responsible for the bed-time beverages of the Aztecs.

Because of this, Short-Tailed Bats are also known as Piper-Eating Bats. They play a mega vital role of seed dispersal in the rainforest. This one, however, was dispersing seeds in the ladies washroom at Palo Verde National Park.
On Bardsey it is the birds, and sometimes the Grey Seals, which provide the soundtrack to our birding. In Costa Rica it was rather different. The constant buzz of Cicadas (see Leaf-cutter Ant video below), provided the background noise but this was regularly interrupted, particularly in the morning and evening, by a piercing chorus of roars. As with most first-time visitors to Central America we were at first puzzled by the source. They turned out to be from the endangered, CITES I listed, Mantled Howler Monkeys.

Adult Mantled Howler Monkey with baby (c) Richard Brown

Leaves provide the majority of the diet and are supplemented with flowers and fruit. Because they use leaves it means that their territories can be relatively small and troops of up to about 20 individuals were encountered relatively often. The calls can be heard at over 3km through the forest, and across water (this troop was photographed from a boat) can be heard at up to 5km.

Central American Spider Monkeys take a much higher percentage of fruit in their diet. Thus they generally move further and faster in order to find enough food. They were usually hard to observe, right up in the canopy of the jungle (c) Richard Brown

Monday, February 14, 2011

The Best Roof in Costa Rica (c) Richard Brown

The best roof in Costa Rica was this one...
It was some sort of batty experiment. We didn't ask, because we were trespassing to see them. But we think it was some sort of hierarchy experiment. Each bat was individually colour coded on its fore-arm. These bats were of the same Sac-Wing family as the ones we saw on the tree, but have the fantastic title of 'Brazilian Long-Nosed Bat, Proboscis Bat or Sharp-Nosed Bat'.
The reason being, they have a long nose.
They too had the parallel lines on their backs, but it was much fainter than the Greater White-Lined Bat. Still, their multicoloured bangles made up for it.

Brazilian Long-Nosed Bat (c) Richard Brown
So who could live in a house like this?

It's about the size of an eggcup but contained two tiny eggs. It was made of cobweb, moss and lichen (c) Richard Brown

The Rufous-tailed Hummingbird which was nesting in a potted plant outside our room near Arenal Volcano (c) Richard Brown

This was the first trip we've had together where we could get to grips with some hummingbirds. And away from reliable food sources, particularly hummingbird feeders, they proved very difficult indeed because of their amazingly rapid speed. The abundant Rufous-tailed Hummingbirds did their best to make matters worse by aggressively defending any food and chasing off other species of hummingbird. But they were stunning so we'll let them off.

Sunday, February 13, 2011

A tree next to a swing bridge at La Selva was probably the best tree of the holiday. That's because, in the brief periods in which no-one was walking across it (causing it to bounce and swing from side to side), six bats could be seen clung to the bark in the shade. They were exceptionally well camouflaged, and you had to know where they were to see them.

 The Best Tree in Costa Rica (c) Richard Brown

Greater White-Lined Bats (c) Richard Brown

Again I (Giselle) was very excited by these bats. Reason the first; in England I have never observed bats hanging on the outside of trees in the daytime. Reason the second; in England, bats do not have crazy white parallel lines running down their backs.

So what are they? Out of 110 species of bat officially recorded in Costa Rica, we whittled these critters down to the title of Greater White-Lined Bat. It wasn't too difficult, as our guide told us what they were.

They belong to a family called 'Sac-Winged Bats' and are insectivores with wing-sacs. Whats the point in having a sac on your wing? Well, the sacs are used socially as scent marking organs.

During the breeding season, individual colonies are defended by one male. To attract a female the male emits a scent from his wing sacs. This is accompanied by a complex song which he performs whilst hovering in front of her. Awesome.
The remnants of a stunning Blue Morpho butterfly. Who could have done such a thing? (c) Richard Brown

A guilty looking Rufous-tailed Jacamar. He done it. (c) Richard Brown
Working through our Costa Rica photos is providing an excellent distraction from report writing. Despite only returning home on the 9th it seems an age ago that we were standing on a boardwalk stretching out into the marshes of Palo Verde, part of the largest wetland in Central America.

Sunset at Palo Verde and the end of a fantastic days birding (c) Richard Brown

Waterbirds were everywhere. Black-bellied Whistling-ducks provided the bulk of the numbers but a huge variety of birds were feeding with them. Northern Jacanas (pictured below) were walking among the vegetation, occasionally flapping their yellow-green wings to escape the attentions of prowling American Crocodiles (and making plenty of noise to alert any other birds in the vicinity). 

Black-bellied Whistling-ducks (with Black-necked Stilts and Blue-winged Teal) (c) Richard Brown


Saturday, February 12, 2011

A very conspicuous feature of the jungle were the ant trails. Brilliant for birding as they attract insectivorous birds and amazing wildlife events in their own right. The Leafcutter Ants were amazing! They form the largest and most complex societies on earth (after us, and to be honest they seemed much more organised than the Costa Rican road system). Nests can be up to 800 square metres and contain 8 million ants!

video
Leafcutter Ants in action. We particularly like the one that's bit off a bit more than it can carry (c) Richard Brown

The trails disappeared into the treetops where the ants were harvesting the juiciest of leaves and little flowers. They then traveled along cleared pathways and took their harvest back to their nests. But the vegetation was not to eat! They grind it down and use it as a fertiliser in their own Fungus Gardens. They then feed the fungus to their larvae. The fungus is specific to the species of ant and needs the ant to tend to its needs if it is to survive.

But how do new colonies form if they need the fungus? The queen setting off to start a new colony takes some in a pocket. In her mouth!
Large reptiles were conspicuous at most of the good birding sites. And whereas the American Crocodiles kept their distance in the rivers and swamps, the Ctenosaur spent a lot of time around our ankles whilst we were birding. At up to four foot long it would be a lie to say this isn't quite intimidating.

The totally harmless Ctenosaur (unless you're a flower or a piece of fruit) (c) Richard Brown

The Ctenosaur has a nifty trick to help manage their temperature. Pigment granules can move within individual skin cells to change their colour. So they can be dark on a morning to warm up and more reflective during the hot midday period. Smaller Ctenosaurs may also use changes in skin colour to help with camouflage as there are plenty of Snakes and Hawks which would make a meal of them. 
Another of our favourite non-avian highlights, was a frog. Not just any frog. A Strawberry Poison-dart Frog, Flaming Poison-dart Frog, or, Blue-Jeans Frog! They're all the same frog, except the two former names suggests something a bit more menacing than the latter.

Strawberry-Poison Dart Frog (c) Richard Brown

While I'd like to say he was menacing, he was about the size of a large grape, and hopped away as soon as we got close. He probably got a bit bored of our pursuit, because he launched himself at Rich's hand (that was poised with the camera a few inches away from his big red face). He clipped Rich's thumb before landing on my boot. On my boot, he was one hop away from entering what he thought was a tunnel of safety, but in reality was my trouser leg. Luckily he chose to hop off into some dead leaves by the side of the trail.

Strawberry-Poison Dart Frogs have some of the most fascinating ecology in the rainforest. When the female picks her mate, based on the best song, she lays her eggs on the ground under a leaf, and the male proceeds to fertilise them. They take turns to guard the eggs. When they hatch into tadpoles, both the male and female frogs put a couple on their back, and climb up a tree in search of a bromeliad. The bromeliad is essential to the survival of the tadpoles, as they contain miniature 'ponds' of water. Every day or two, the female climbs up to the bromeliad and lays a couple of unfertilised eggs for the growing tadpole to feed on. Nom nom nom.

Friday, February 11, 2011

And the highlight for me (Giselle) was the Honduran White Bat. Three to be precise. They roost under large leaves, which they perforate along both sides of the stalk in order to make a tent, and therefore be hidden from predators.

 Honduran White Bat (c) Giselle Eagle

Leaf adapted into a tent, under which the three bats were clinging. (c) Richard Brown

The Honduran White Bat only roosts in leaf-tents, and is one of the few species of bat to adapt its surroundings in order to roost. They are frugivorous, and their white fur is cryptic under the folded leaf, reflecting the green light passing through the leaf, and rendering them virtually invisible to predators. To make matters even cuter, they are about the size of a cotton wool ball, and have yellow-ish ears and nose. 
There are approximately 110 known species of bat in Costa Rica, of which we only saw (or were able to identify) 4 species. For such a small country, this is a mega number and they have a fantastic inextricable relationship with the forest ecosystem, being the sole pollinators of many flower and tree species, and of course acting as a natural insect control!
And the highlight of the holiday? For me (Rich) it had to be a White-collared Manakin lek, at least six males in dappled sunshine, bouncing around and wing clapping. Real Life of Birds stuff.

White-collared Manakin (c) Richard Brown
Having the freedom to drive where we wanted meant that we could experience the huge diversity of Costa Rican wildlife. The morning could be spent in Central America's largest wetland, the afternoon in montane cloud-forest. A morning birding volcano top endemics was followed by an afternoon in Caribbean lowland forest. I think its this huge diversity that made Costa Rica such an amazing place to visit.

Collared Aracari (c) Richard Brown

It was fantastic to be surrounded by birds so different to those we see at home. Aracari, Toucans, Hummingbirds, Tanagers, Antshrikes, Trogons, Parrots and Guans were always on hand to provide a touch of the spectacular. Families that we were more familiar with were represented by birds hugely different to our own.

A Squirrel Cuckoo. At first glance this large cuckoo could be mistaken for a squirrel as it leaps between trees and scurries along the branches. This one had taken an Anole Lizard which seemed to be making a failed attempt to startle its captor with its dewlap (c) Richard Brown

And the birds were not the only stars of the show. The forest contained Capuchins, Howler Monkeys, Spider Monkeys, Peccaries, Sloths, all manner of rodents, bats, lizards and a mass of invertebrate life was on constant display.

A Hoffman's Two-toed Sloth. Apparently the leafs these guys munch are rather similar to a very potent cannabis. Perhaps this goes someway to explain their rather sluggish behaviour. The energetic highpoint of the week will be a visit to the forest floor for a crap (c) Richard Brown

A Basilisk or Jesus Christ Lizard. The youngsters are capable of running along the surface of water to escape predators. Bigger ones such as this tend to swim (c) Richard Brown
We've just got back from Costa Rica. Some might say it was a Bus-man's holiday,  but I don't think Bus-men are as excited by buses as we are by birds, bats and other wildlife*. I (Giselle) doubled my life list of birds in just two weeks. And it was the first time Rich birded abroad with his big camera.

We hired a 4x4 and chanced the earthquake displaced roads and unnerving over-taking opportunities to visit as many different amazing habitats as we could fit in. I was the navigator. Costa Rica has no road signs. And, furthermore, they've built new roads and not put them on maps. But I only got us lost twice, and we (Rich) figured it out both times. The roads shouldn't dissuade you from visiting Costa Rica though, and since I was only a passenger, I quite enjoyed them.

*Based on my sole experience of the angry  bus driver on the X25 from Blyth-Newcastle during the years 2003-2006 inclusive.

Violet-headed Hummingbird (c) Richard Brown

The hummingbirds were mental, and the ultimate ID Challenge, since they were so fast, and appeared a different colour at every angle.

Northern Jacana (c) Richard Brown

Since I've never birded abroad before, the species which I most wanted to see weren't necessarily Costa Rican endemics. Since buying my first guide to Waders of Europe and North America, I've desperately wanted to see a Northern Jacana and marvel at his lime green underwings. We visited a place called Palo Verde, which hosts the most extensive wetlands in Central America. And, a quick walk along a dubius boardwalk into a marsh where water hyacinth grew sensibly, we found hundreds of Jacanas! Contesting males, females and juveniles were all plodding around in the shallow marsh amongst Black-bellied Whistling Duck, Black-necked Stilt, Limpkin, Green Heron, Little Blue Heron, Great Blue Heron, Snowy Egret, Great Egret, Tri-coloured Heron, Glossy Ibis, White Ibis, Blue-winged Teal, Fulvous Whistling Ducks, Bare-throated Tiger Heron, Muscovy Duck, Purple Gallinule, Anhinga, American Coot and Roseate Spoonbill. And that was all in the same binocular view. And to top it all off, soaring close to the water's surface was a Snail Kite! Fantastic!