Friday, October 30, 2009

Fruit eaters the world over (with no teeth)

Those cherry-tossing waxwings in the last post got me musing about other fruit tossers from around the world. Indeed, fruit is such a wonderful resource that part of the world’s avian diversity is due to this rich food source. So, I thought I dig up some more photos of the ways birds of many feathers devour fruit.

Why not start in the Neotropics where the abundance of fruit has created such fascinating life forms. Some of the fruit eaters you’ll find here are large non-passerines such as this handsome White-tipped Quetzal, a member of the Trogon family (Trogonidae), from the northernmost portion of South America. Quetzals and trogons are not shy of swallowing large fruit (they love wild avocadoes) as this bird is about to…


The Neotropics are also home to one of the most famous fruit-eating non-passerine families, the toucans (Ramphastidae). This is a Keel-billed Toucan I photographed in Mexico. The red bill tip has earned this species the nickname “matador” (killer) in parts of Mexico and Central America. The massive bill doesn’t stop them from deftly picking even tiny fruit at times! The teeth-like serrations on the tomia (edge of the bill) of toucans (more pronounced in some species than others and only barely visible in this photo) are an adaptation to plucking and eating fruit. When the first specimens were brought back to Europe, puzzled European ornithologists concluded toucans and ara├žaris must be fish eaters due to this feature (pity they didn’t consult the South American ornithologists of the day first!)


Relative to the toucans are the barbets, although whether you group these in the same family as the toucans or not depends on which taxonomic authority you prefer to follow. Although toucans are restricted to the Neotropics, barbets are found in the Neotropics, tropical Africa and the Oriental Realm (Asia south of the Himalayas and the Yangtse River to oversimplify). This bird is a juvenile Red-throated Barbet from Malaysia (the family being Megalaimidae “Asian barbets” if you don’t lump all barbets and toucans into one family). This bird may not have developed the colourful red facial pattern of the adult but they sure know how to dive into red fruit!


Meanwhile another Asian barbet, the Golden-whiskered Barbet, photo from Malaysia (old scanned slide, sorry), has a family to feed and demonstrates the fine art of fruit cramming…


Still in South East Asia, another non-passerine family, the parrots (Psittacidae) also love fruit. This Long-tailed Parakeet is snacking on palm fruit in Singapore. Parrots have zygodactyl feet (two toes forward, two toes back, which is a slight simplification because trogons also have two toes forward and two toes back but their feet are called heterodactyl – it’s a different toe that gets “reversed”) and they use their foot structure very well to manoeuvre fruit and other objects, as this bird is doing to get better leverage on this large fruit.


The Scarlet-fronted Parakeet from South America also shows how frequently parrots use their feet in this manner. First, the fruit is plucked with the bill, which may require a little acrobatics, then manoeuvred into place with the aid of a trusty zygodactyl foot (note the two toes pointing down)…



Moving into the passerines, this female Andean Cock-of-the-Rock from northern South America is one of the many dazzling species in the Cotinga family (Cotingidae) in the Neotropics. The Cotingids are fruit eaters par excellence and almost every aspect of their evolution and radiation can be traced to the opportunities and challenges posed by a frugivorous lifestyle in a fruit-rich area.


Many of the Neotropical cotingids seem rather relaxed, like this large Red-ruffed Fruit Crow, pausing between picking tasty figs in the same tree as the Andean Cock-of-the-Rock above. If they seem relaxed, it is the luxury of an abundant food resource, fruit, that makes their life relatively easy and driven their evolution towards, for the most part, gaudy showy males (some even with display leks), whilst females are better camouflaged and perform all family duties as single parents (the gaudy males would probably just be a liability around a nest).


Thrushes (Turdidae) are another family that are fond of fruit, though you can tell from their long thin bills that they haven’t evolved with total devotion to fruit (those medium length thin bills are good for picking grubs too – an omnivore's solution!). So, especially when they tackle large fruit, thrushes sometimes have to be a bit creative in their approach. Allow this female Varied Thrush from North America to demonstrate… if at first biting, pulling and tearing don’t do the trick, then gripping the fruit and shaking the head rapidly soon get her to the heart of the matter…



Two other American thrushes, Swainson’s Thrush and Hermit Thrush, are also fond of fruit. (I say American because they venture down to the Neotropics in winter and the Swainson’s goes all the way to South America). When times are rough, i.e. cold, and there aren’t many insects to be found, fruit is what will get them through. As these birds show, sometimes the easiest way to handle fruit is on the ground! By the way, can you tell which thrush is which?


An aberrant thrush from South East Asia, the aptly-named Fruithunter, endemic to the island of Borneo and in their own monotypic genus, also seems somewhat slow-moving. As a result this species is very difficult to detect in the canopy and I spent many hours hiking up and down Mount Kinabalu in Borneo before I lucked into this bird paused between feeding bouts on the small fruit visible in the background.


This Little Greenbul from western Africa, a member of the bulbul family (Pycnonotidae), another family of omnivores with a penchant for small fruit.

The Olive-winged Bulbul from Southeast Asia, a smiliar looking relative to the greenbul, even feeds large fruit to their young - no luxury of a blender!

This Stripe-throated Yuhina from southern China, a member of the large, predominantly Asian babbler family (Timaliidae) seems to manage the fruit-tossing technique shown by our waxwings in the previous post… but while hanging upside down! Hanging upside down to pluck fruit is common in birds but defying gravity with enough speed to perfect the repositioning toss in this position takes quite a bit of practice…


Speaking of waxwings, here a fruit-loving relative of theirs, the Gray Silky, a.k.a Gray Silky-Flycatcher, from the very small family known as silkies or silky flycatchers (Ptilogonatidae), with a more Neotropical distribution than the Holarctic waxwings, though one member, Phainopepla, reaches the Nearctic.

The flowerpeckers (Dicaeidae) are a fascinating family of tiny passerines (8 – 12 cm) from the Oriental and Australasian realms. Despite their small size, they seem to be voracious fruit eaters. This Yellow-rumped Flowerpecker from Borneo enjoys a sticky snack…

Whilst this male Scarlet-headed Flowerpecker on Bali takes on a fruit that seems larger than his gape (yes, he got it down!)


The tanagers (Thraupidae) are another family that love fruit and which owe much of their evolutionary colour to the wondrous resource that is fruit, at least in the Neotropics, where their arrival in the Great American Interchange (mingling of fauna when North and South America came into contact) produced a staggering evolutionary radiation of colour and forms… Here are but a few examples: A Blue-capped Tanager picking small bite-sized fruit,


A male Flame-rumped Tanager enjoying a sticky fruity meal, whilst cleverly managing to keep his feet clean,


And a Bay-headed Tanager, picking off pieces of a long fruit, using the time-honoured upside-down approach.


In the Nearctic, tanagers are omnivorous but they seem to eat insects much more than fruit, at least in the breeding season. Yet in South America, the reverse (more fruit, less insects), seems true. You gotta with what’s most available! That is why I say that the abundance of fruit in the Neotropics influenced the evolution of the tanagers… And look at the result, there at over 180 species called “tanager” (let’s temporarily ignore groups like hemispinguses, dacnises, honeycreepers, conebills, flowerpiercers, spindalises and many others that are usually placed in the same family) of which no more than a dozen occur in North America and the rest are in Central and South America. Perhaps even more interestingly, when some migrants that we think of as insectivores here in North America arrive in the Neotropics they may switch to include fruit, capitalising on an abundant resource – the Eastern Kingbird, from the quintessentially insectivorous tyrant flycatcher family (Tyrranidae), is one such example!

Last and almost least in terms of size (after the flowerpeckers), a male Blue-naped Chlorophonia, plucks a tiny juicy fruit. Just what family these little gems belong to few taxonomists seem to agree on. The IOC put them in the Fringillidae (finches) for example, whilst others give up and go with “Incertae Sedis” (place uncertain). If they are finches, they have long ditched the typical seed-eating lifestyle of their ancestors, and have developed their own way, thanks to, you guessed it, fruit!


Nothing like a post from around the world to make me run on long! You can view larger files of some of these photos with more details on where I took these photos, as well as other families of frugivorous birds, at http://www.artusophotos.com/. Hmn, think it’ll be bananas for breakfast for me tomorrow! Maybe even mammals are what they eat...

2 comments:

  1. Wow,that was most informative.These are most likely birds I will never see in person,so this was great.Thanks.
    Blessings,Ruth

    ReplyDelete
  2. I'll second Ruth's comment - nicely done and very informative. An interesting read!

    Dave Ingram

    ReplyDelete

 
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