Sunday, December 5, 2010

Peru: Part 2 - Dry Forests

As I mentioned in “Owls of Peru – Part 2: Arid Habitats” (posted in October), western Peru, i.e. west of the Andes, experiences a formidable rain shadow that creates some of the driest place on earth (technically the driest places occur a little further south in Chile due to the same rain shadow). As I wrote, all the moisture ascending the Andes from the Amazon basin (the prevailing winds are from southeast in this region) gets sucked out on the eastern side as it condenses into rain or snow. By the time the air mass crosses the Andes and descends the western slope, there is almost no moisture left in it. The western Andean foothills and coastal areas are therefore dominated by dry desert-like conditions or tropical dry forests that are much less tall and lush than the humid forests on the eastern slope. These forests are correspondingly lower in biodiversity but they do have their share of endemism as many species evolved here in isolation (cut off from relatives by the mighty Andes). This post offers a glimpse at some of the wildlife of this region.

We start with one of the most famous inhabitants of this region – the White-winged Guan. This species was discovered in 1876 but then not seen again for nearly 100 years and long feared extinct. A tiny population was fortunately rediscovered in northern Peru and since then conservation measures have been put in place including a captive breeding and reintroduction program. Nonetheless they are still classified as critically endangered with probably fewer than 250 individuals in the wild. I took these photos of these beautiful birds at Chaparrí, where a single wild guan was found and then some of the progeny of the captive breeding birds were released, making them easier to see here than elsewhere. The first photo shows a bird foraging in the treetops along a ravine. If you look at this photo you might be surprised by the name White-winged Guan. If you look at the second photo, where the bird has a slightly different posture, you can see a hint of white in the wing – in fact there is a large white patch that is only visible when the wings are open.



Raptor diversity often seems quite high in open habitats and coastal Peru has some beautiful raptors to behold. This is the elegant Pearl Kite.


And this is Savanna Hawk. This species is well adapted to arid habitats of northwestern Peru - their long legs (unfortunately not so visible in this photo) aiding in hunting and in locomotion along the ground.


There are numerous dove species in these dry forests. Here is just one example, the Croaking Ground Dove.


The Pacific Parrotlet is a common species in these dry forests, although their small size and active movements can make them tough to see well without a little luck.


Among the woodpeckers in these habitats, the small and beautiful Scarlet-backed Woodpecker occupies some of the very dry scrub habitats and thorny forests in the coastal regions and foothills (notice how “un-green” the habitat in the background of this photo appears).

The Lineated Woodpecker, on the other hand, is a large woodpecker and hence requires large trees. They tend to prefer riparian (river edge) forest, which in these dry areas is much taller than the surrounding scrub. This species is a congenitor of the Pileated Woodpecker (genus Dryocopus).


Hummingbird diversity is not particularly high in these dry areas but there are enough seasonal flowers and nectar that a few species can make a living here. By far the most common is the Amazilia Hummingbird. This species is one of those where the genus and species names are the same (Amazilia amazilia) and they also carry this name into their common name (Amazilia is a very large genus of hummingbirds with 30 species).


Leucippus is a much smaller genus of hummingbirds (4 species), two of which occur in this area – the Tumbes Hummingbird in the dry forests of northwestern Peru and the the very similar Spot-throated Hummingbird shown here that occurs in the dry Marañon valley at slightly higher elevations.


Here a young Purple-collared Woodstar takes a bath at the now famous mini cascade at Chaparrí. In such dry habitats, water is a very attractive feature to many birds including hummers!


Almost anywhere in South America, diversity is very high in the suboscine passerines. In North America most of our passerines are the oscines (sometimes dubbed “true songbirds”) and there is essentially only one family of suboscines, the Tyrant-Flycatchers. The main difference between the oscines and the suboscines is in the complexity of the syrinx (equivalent of our larynx), which of course gives the songbirds such beautiful voices. Suboscines may not have as complex songs capability as oscines but they can still fill up your senses! Prior to the Great American exchange (when the two continents came into contact), North America was completely dominated by oscines and South America dominated by suboscines. During the Great American Exchange a lot of mixing occurred so that both groups now thrive on both continents; however, the suboscines are still in the majority (just) in most of South America. For example, approximately 55% of Peru’s ~870 passerines species are sub-oscines. So here is a glimpse of this diversity…

Since many readers will be most familiar with the tyrant-flycatchers as example of suboscines, let’s start there. North American readers will be familiar with the genus Myiarchus, to which species like Great Crested Flycatcher and Ash-throated Flycatcher belong. Well, in the driest forest and scrub of northwestern Peru there is a beautiful Myiarchus species, who, to my eye, looks unlike other Myiarchus, viz. Rufous Flycatcher (again notice how arid the scrub in the background of the photo is).

One of the highly sought after endemics of the Tumbes regions (northwesternmost Peru and southwesternmost Ecuador) is the Tumbes Tyrant. This little gem can be very inconspicuous, despite their rich colour. The first photo shows the thorny dry forest they inhabit and the second show the rich colour of this species.



This Yellow-bellied Elaenia was hanging out right in a treed town square, perhaps a little more shady than the surrounding scrub.


Some of the flycatchers in this habitat have evolved to look a little different than the flycatchers most North Americans are used to. Here is one example, the Short-tailed Field-Tyrant. Notice how this species has evolved very long legs, which accompany their predominantly terrestrial habits (foraging by hopping along the ground). Of course they do occasionally perch on shrubs, as shown here, when their short-tailed, lanky profile seems a little out of place. You can see how small this bird is by comparing them to the acacia thorns in the photo.


In Part 1 of this series, I mentioned the ovenbird family. In addition to the miners and cinclodes there are other groups within this large suboscine family. This is a Pacific Hornero, foraging amidst the dry leaf litter. The word hornero is Spanish for oven maker (horno “oven” is cognate of Italian forno, both from Latin fornus; English “furnace” coming from Latin fornax via French and the English word “warm” being derived ultimately from the same Indo-European root). These birds make large oven-shaped mud nests that give them their name and give their family (Furnariidae) its name. Some Peruvians told me that the local legend is that these birds taught the locals how to build their houses (houses are frequently made from adobe in this region).


The antbirds (Thamnophilidae) is another very large suboscine family. Some of this family are myrmecophiles (ant lovers) who follow army ant swarms to feed on any living thing that flees from the advancing ants. In dry habitats, it seem that the antshrikes are the most common representatives of this family (not myrmecophiles). Like so many groups within this family, their names are constructed with the prefix ant- and then the name of another groups of birds they resemble (examples include antshrikes, antwrens, antvireos, and others). You will notice the shrike-like hooked bill of this female Collared Antshrike.

And here is her partner (I have not read anywhere that females have a more hooked upper mandible than males but on the few occasions where I observed a pair together that seemed to be the case)...


This male Shumbae Antshrike of the dry Marañon Valley may look A LOT like the male Collared Antshrike above, but recent genetic studies suggest they should perhaps be treated as separate species. Can you spot the differences in plumage?


This female Northern Slaty Antshrike was skulking in the thick shrubs and very difficult to get a good photo of… (the male is the "slaty" one)


Still within the antbird family, this Rufous-fronted Thornbird is constructing their enormous nest out of sticks rather than mud. These little brown jobs are inconspicuous most of the time, except their gigantic nests very often give their presence away (how often can you say it is easier to find a bird’s nest than the birds themselves?).


Another interesting suboscine family from this region are the Crescentchests (Melanopareiidae), formerly placed within the larger Tapaculo (Rhinocryptidae) family. There are only four species of crescentchest in the world and two of them occur in northwestern Peru. This is the Elegant Crescent of the coastal dry forests. Look closely at the wing before you scroll to the next photo.


This is the very similar Marañon Crescentchest of the dry Marañon Valley. Notice the white in the wing of this species as compared to the Elegant Crescentchest. As in the Shumbae Antshrike example, genetic studies and other evidence suggest that many taxa of the Marañon Valley are reproductively isolated from their close relatives of the coastal dry forest and more and more of them are being split as separate species.


This Peruvian Plantcutter is a representative of yet another suboscine family, the Cotingas (Cotingidae). This species is very patchily distributed in dense thorn forest. Unfortunately, in this photo you cannot see the serrations on the bill that give them their name.


Moving now to the oscines, here is an example of a group with a complex vocal repertoire even if they are not known to be beautiful songsters – the Crows and Jays (Corvidae) – yes, that is right, crows and jays are “true songbirds”. This is the stunning White-tailed Jay, which looks extremely similar to the Tufted Jay of Mexico but is much smaller. These birds can look very black and white when in shadow…

But with a little sun, such as on this bird in flight, you can see their "true blue"...

The Long-tailed Mockingbird is a birder's constant companion in dry coastal habitats.

The colourful Peruvian Meadowlark is not quite as common as the mockingbird but always a treat to watch.


There are numerous small seed-eaters in these habitats from several groups. Here are some examples, starting with the Little Inca Finch (this is a juvenile). The Inca finches are in the genus Incaspiza, which contains five species and the whole genus is endemic to Peru, i.e. all five species are found nowhere else... just amazing!!

Some of the seed in the dry forests must be hard to crack – just look at the honking bill of these Parrot-billed Seedeaters (female left, male right)!

The large Cinereous Finch is no slouch at husking seed either. This is another of the endemics of the Tumbesian region.

The Chestnut-throated Seedeater, on the other hand, doesn’t need such brute strength to earn a living.

This is the handsome Collared Warbling Finch with yet another slightly different bill structure for feeding on a different variety of seed.


And this the classy Saffron Finch


And the Red-crested Finch of the Marañon Valley and the Urubamba Valley.


The Tumbes Sparrow is yet another endemic seed-eater of the Tumbesian region. They are in the genus Aimophila along with North American sparrows such as Five-striped Sparrow, Bachman's Sparrow and others)

Naturally, there is more than birds to view in the dry forests. Here are just few examples of other wildlife. The Handsome Sechuran Fox (named after the Sechuran Desert). They are easy to see at Chaparrí as the second close up shows…



And a Collared Pecary


And a Green Iguana, which despite their name are not always green (the young ones are green but adults vary in colour)...

4 comments:

  1. Thanks for sharing these birds.I will likely never get to that area,so this is the next best thing.
    Blessings,Ruth

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  2. What a neat "tour"! Great photos, the White-Tailed Jay is amazing! I esp. like the Amazilla Hummingbird and Tumbes Tyrant pics!

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  3. In Peru, I photographed a bird nest that is large and made of mud. It is completely enclosed except for a crescent shaped entrance hole. A tour guide (not a naturalist) told me it was the home of a Chachalaca. I see from further research that is much more likely to be the nest of a Rufous Horneo. The only problem is that the Ovenbird, Rufous Horneo does not live in Peru. Anyone have any ideas?

    ReplyDelete
  4. Hi Jemala,

    Almost certainly the nest of Pacific Hornero or onew of the hornero species in range

    Christian

    ReplyDelete

 
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