Day 67: Rainbow bee-eater – Merops ornatus
No sting in the tail
Bee-eaters are a charismatic group
of birds in the family Meropidae. They are conspicuous birds, known for their
bright and varied palette of plumage colouration. They are also conspicuous in their
behaviour, frequenting prominent perches such as telephone wires from which
they can spy prey up to 50 m away. They are capable of catching all manner of
insects on the wing but, as the names suggests, bees can form a large part of
their diet. Large and/or venomous prey is taken back to the perch where it is
neutralised with bashing and scraping. Aerial insects abound so foraging
opportunities are plentiful. Bee-eaters are limited more by nesting
opportunities, requiring dry substrates in which to build their burrows. They have a largely tropical and subtropical distribution across the
Old World with many species migrating annually.
The rainbow bee-eater is a
typical bee-eater species. It is, however, the only species I have seen
(despite multiple trips to the Med where European bee-eaters can be found).
Rainbow bee-eaters were a common sight for me in the open areas of the Daintree
Rainforest in Queensland. They are by no means confined to this habitat,
perching anywhere where flying insects are in abundance including parks and
gardens. I was observing them during the winter/dry months after they have spent
the summer breeding in Southern Australia. They are a fun bird to watch and their
bubbly calls are a delight.
The Meropidae, along with the
three kingfisher families, are members of the order Coraciiformes. Coraciiforms
lack a unifying name despite being generally colourful, small-to-medium-sized
predators. The order includes the acrobatic, Old World rollers (Coraciidae),
the stockier, Malagasy ground-rollers (Brachypteraciidae), the Neotropical, long-tailed motmots (Momotidae) and the tiny Caribbean todies
(Todidae). Formerly a member of this order, the cuckoo roller (Leptosomus discolour) is an obscure bird
from Madagascar and the Comoro islands now placed in its own order:
Leptosomiformes.
Day 68: Southern ground hornbill – Bucorvus leadbeateri
Luscious lashes
This looker is the largest
species of hornbill. Hornbills are notable for their large, curved bills which
resemble cows’ horns (buceros in
Greek). Their bills, supported by their uniquely-fused first two vertebrae,
serve a variety of purposes including nest construction, fighting and preening
but their most obvious use if for crushing food such as fruit and small animals.
Many species have a hollow casque atop the bill which can be used to resonate
calls or to joust with competitors (in the helmted hornbill, Rhinoplax vigil). Whilst their plumage is
usually dark, the bills and naked facial skin of hornbills is often brightly coloured
with yellows and reds that reflect the carotenoids of their diet. Once again,
this is classically honest signalling of health for mate choice.
Hornbills are largely
arboreal, found in habitats from savannah to rainforest across Africa, southern
Asia and Melanesia. The Southern hornbill and its
sister species (the Abyssinian ground hornbill, B. abyssinicus) are a bit of an exception amongst the hornbills,
being far more terrestrial than their relatives. In fact they might forsake the
trees altogether were in not for the tree cavities in which they need to
nest. The two ground hornbills can be found striding across the plains of
sub-Saharan Africa in search of small vertebrates and large invertebrates. To
cope with the dusty habitats in which they forage, the ground hornbills have
very long lashes and bare skin around the face and throat. In the Southern
ground hornbill, this skin is bright red.
Ground hornbills are some of the
most (if not the most) long-lived birds with life expectancies around 30 years
and with individuals living up to 70 years in captivity. They are also obligate
cooperative breeders. Individuals must spend half-a-dozen years assisting at
the nests of older birds (parents) before becoming breeders themselves. Cooperative
breeding always necessitates explanation. Usually in birds it is a bet-hedging
strategy; if it is too risky to start your own family (i.e. low chance of
success) better to stay at home and help rear your younger siblings. Perhaps
the risk in starting a new family for hornbills is either not gaining a
suitable territory (or nest site) or not being able to bear the costs of
rearing large chicks without help.
Ground hornbills share the family
Bucorvidae with the Bycanistes genus
of hornbills. The rest of the hornbills, from the small, African Tockus species to the large, casqued Buceros species, are found in the family Bucerotidae. Hornbills
traditionally had the order Bucerotiformes to themselves but recently they have
been joined by hoopoes (Upupidae) and wood-hoopoes (Phoeniculidae). Hoopoes (Upupa epops) are a fantastic bird with broad,
barred wings and a salmon pink head and crest. Their name is an onomatopoeic
rendering of their call (an oop-oop-oop)
as is their generic name Upupa whilst
the specific epithet epops was the
name of a hoopoe in the Ancient Greek play The
Birds by Aristophanes.
Day 69: Emerald toucanet – Aulacorhynchus prasinus
Big-billed birds
Whilst bearing a passing resemblance
to hornbills (although not the species pictured above), the toucans, toucanets and aracaris are quite unrelated with
their own family, Ramphastidae, in the order Piciformes. Their resemblance (especially the large,
flashy bills) reflects the convergent evolution of toucans into a similar niche
of arboreal faunivory but in the forests of the Neotropics. Although sometimes making
up more than half the length of the bird, the toucan’s beak is surprisingly light,
being filled with spongy keratin. Serrations on their billss allow toucans to
crush fruit whilst the length allows them to lazily reach many fruit without
having to move. As with hornbills, toucan beak are huge advertising boards of colour.
The emerald toucanet is (as the
name suggests) one of the smaller toucan species. Though their bills are not as
brightly coloured as some of the larger toucans and aracaris, the plumage of
the green toucanets (Aulacorhynchus
spp.) is vivid, the bright green sometimes embellished with red or blue. The emerald
toucanet was my first wild toucan, seen feeding in the cloud forest canopy of
Honduras. This was closely followed by the ornate collared aracari (Pteroglossus torquatus) and the spectacular
keel-billed toucan (Ramphastos sulfuratus).
Day 70: Greater honeyguide – Indicator indicator
Show me the honey!
As mentioned above, toucans are
members of the Piciformes. This is the last order of birds on our list so the end is very much in sight! I do not have space to detail the
bee-eater-like jacamars (Galbulidae) and the related puffbirds (Bucconidae) nor
the four, chunky barbet families. However I will, of course, discuss at length
the largest piciform family: the woodpeckers (Picidae). But first, honeyguides.
Honeyguides (Indicatoridae) look
a bit out of place in the Piciformes, an order of well-built birds with large
heads and beaks. In fact the honeyguides look like passerines, the humongous
order of perching birds which would come next in the sequence however you should note the woodpecker-like zygodactylic feet. Although they are
relatively dull birds, honeyguides are unusual in their regular consumption of
wax which is taken mainly from bee hives. The greater honeyguide, feeds on the
eggs, larvae, pupae and wax of bees nests and this has lead to a surprising
relationship with man. As suggested by both the common name and the Latin Indicator, honeyguides lead humans (African bushmen) to
honey.
Honey-guiding is a classic of
example of a mutualism where individuals help each other for mutual benefit (symbiosis
is a word often used instead of mutualism but symbiosis actually refers to organisms
that inextricably depend on others where this relationship is not necessarily mutualistic. Conversely
mutualists need not be obligate mutualists, but merely cooperative from time to
time). It is relatively easy to explain this mutualism as a form of ‘partner
choice’ where both parties must cooperate in order to receive the reward.
Honeyguides lead hunters to bees’ nests with loud, distinct calls. After the
humans have smashed open the nests and taken the honey, the birds can eat their
fill. If the humans were to cheat the system, leaving nothing for the honeyguides, the
selection pressure for the birds to guide would disappear followed by the behaviour itself.
Likewise, the birds save a lot of time guiding the humans rather than waiting
for them to find the bees themselves. Thus cooperation is needed on both sides
for a successful relationship.
Honey-guiding has only been demonstrated in this Indicator species despite the whole family sharing the name. One thing all members do share is brood parasitism, as seen in the cuckoos.
