letting nature back in

We often hear woodpeckers tap-tap-tapping on wood as they search for food in the trees in our suburb most of the year round. They are also quite vocal, but despite all this noisiness they can be difficult to see as they are mostly high up among the branches and foliage of the taller trees.

In addition woodpeckers tend to be wary and often flit off when snooping humans approach on the ground below them. Despite all this, I have managed to photograph the three species of woodpecker that visit our garden.

The smallest is the Cardinal Woodpecker, the commonest and most widespread of African woodpeckers, and because of their calls and tapping I am often aware of a pair foraging together in the garden.

The female Cardinal Woodpecker like the male has a brown forehead, but unlike the male the crown or top of the head is entirely black

The crown of the male Cardinal Woodpecker is red. The male and the female Cardinal Woodpeckers both have distinctive barring rather than spots on their backs

Adult Cardinal Woodpeckers form monogamous breeding pairs and they commonly forage together. They use their barbed tongues to extricate insect larvae and pupae from cavities that they have pecked open in tree trunks and branches. They also glean insects and spiders from thin branches and twigs.

This male has found something to eat while probing a cavity in a branch

He uses his tail for balance

The female is also having foraging success

Both birds in a breeding pair share in excavating a hole for nesting that is usually in a dead branch in a tree. They brood once a year and typically there are two eggs in a clutch. When not breeding they roost at night on their own, in a hole in a tree, usually returning to the same hole each night.

The call of the Cardinal Woodpecker is a repetitive chittering sound, no match for the almost raucous call of the Golden-tailed Woodpecker, which is a single high-pitched screech that can be uttered several times at intervals. Golden-tailed Woodpeckers also forage in trees, and like most woodpeckers they seek out dead branches or dead trees when searching for food. They use their sticky tongues to catch insects, including ants.

A pair of Golden-tailed Woodpeckers probing for insects. The male is at the top left showing his red nape. His crown and forehead are dark with red speckles, whereas the female, also with a red nape, has a black crown and forehead speckled with white

A male Golden-tailed Woodpecker showing his red and speckled-black malar stripe and a back that is spotted rather than barred as in the Cardinal Woodpecker

Like the Cardinal and other woodpeckers they excavate nesting holes in trees. Both adults participate in incubating the eggs and raising the young. As for Cardinal Woodpeckers their nests may be parasitized by Honeyguides.

A male Golden-Tailed Woodpecker with traces of recently found food on his bill – perhaps small larvae or insect eggs

The third species of woodpecker that visits our garden is the Olive Woodpecker, which was the subject of an earlier blog post. The Olive Woodpecker is the only non-speckled woodpecker in the Southern African region.

Of the three species that occur in our garden, this species is larger than the Cardinal Woodpecker, but slightly smaller than the Golden-tailed Woodpecker. To get an idea of the relative sizes, the average length and weight of the small Cardinal Woodpeckers is 15 cm and 30 g; of the Golden-tailed Woodpecker 21 cm and 70 g; and of the Olive Woodpecker 20 cm and 45 g.

I rarely see woodpeckers at the bird bath. However, this male Olive Woodpecker stuck around for a lengthy drink. I took this photo in late winter a few years ago

A male Olive Woodpecker, showing his red crown, investigating a log with a nesting hole that we had made and then hung in a tree with the intention of providing a home for Black-collared Barbets. It was never used for nesting but it is possible it was used for a time for night-time roosting by the Olive Woodpeckers

The female Olive Woodpecker, with a grey head and grey crown, also investigating the nesting hole in a log that we provided. Olive Woodpeckes roost at night in a tree cavity, returning to the same cavity each night and roosting in the same hole together, unlike Cardinal Woodpeckers where each bird roosts in a hole on its own

Although not the clearest of photos, I include this shot because it shows an Olive Woodpecker protruding its tongue. The long tongue is barbed and is used to extract insect larvae and pupae from cracks and from under bark and moss

Although the earlier blog post on the Olive Woodpecker reported on a male woodpecker drumming on a window frame, such drumming activity is not common among Southern African woodpeckers, unlike many North American species of woodpecker, for example.

Roberts (Multimedia edition) reports that in Olive Woodpeckers both sexes “drum infrequently and softly”, Golden-tailed Woodpeckers drum “weakly in slow rolls” lasting about 1.5 seconds, and in Cardinal Woodpeckers “both sexes drum; a brief, soft, resonating grrrru, repeated up to 30 x, using the same point on a dead branch as a resonating board. Baobab Adansonia digitata fruits and metal poles [are] sometimes used for the same purpose”. I have not ever noticed drumming behaviour in any of these species.

A pair of Olive Woodpeckers foraging companionable together in the bark of a Wild Pear (Dombeya rotundifolia) in our garden

Although in the breeding season woodpeckers may spend some time engaged in territorial drumming on suitably resonant materials, mostly they use their bills for pecking wood, chiselling off or lifting bark, and probing lichen or moss as they search for food.  Research into how woodpeckers can survive their continuous pecking on hard surfaces without sustaining concussion has revealed anatomical specialisations that work together to protect a bird’s brain while it is engaging in ongoing head-banging in its search for food. This protective system is complex and ongoing research continues to shed new light on the multifaceted mechanisms and relationships that combine to defend the bird from injury.

The woodpecker’s skull structure, bill shape and structure, and the muscles of the neck are adapted to both disperse and absorb the force energy of each blow. Most of the energy is absorbed by the whole body and the force energy absorbed by the brain is mostly in the form of heat. The bird has to rest periodically when pecking to disperse the heat generated.  

The skull has specially adapted bones that are flexible and plate-like to absorb and disperse the shock. The flexible hyoid bone is uniquely adapted in woodpeckers so that it connects to muscles in the tongue and throat and then wraps around the back and top of the skull and may act something like a seatbelt to protect the brain. In addition the shape, size and position of the brain as well as the small space for cerebrospinal fluid minimises the potential for brain movement within the skull.

The Cardinal Woodpeckers in our garden are nowhere near as rapid-fire in their pecking as some woodpeckers in the world, but I include the short video (above) of a male Cardinal Woodpecker seeking food in a dead Natal Fig (Ficus natalensis) tree in our garden. I repeat the short sequence in slow motion and end with very short clip taken just before the bird decided to fly away

Sources: Chittenden, Hugh, Davies, Greg & Weiersbye, Ingrid. 2016. Roberts Bird Guide: Illustrating nearly 1,000 Species in Southern Africa (2^nd edition). Cape Town: Jacana; Miller, Alison. 2018. “Strategy. Skull protects brain from impact. Woodpecker.” https://asknature.org/strategy/skull-protects-brain-from-impact/; Hauserman, Samantha.   “Why don’t woodpeckers get headaches?” Arizona State University. https://askabiologist.asu.edu/plosable/woodpeckers; Orwig, Jessica. 2015. The miraculous reasons woodpeckers can slam their faces into trees all day and never get brain damage. Business Insider October 17.  https://www.businessinsider.sg/why-woodpeckers-dont-get-brain-damage-2015-10/; Roberts VII Multimedia PC Edition.  1997-2016 Southern African Birding. For details go to http://www.sabirding.co.za/roberts7/portal.html; Wang.et al. 2013. “Biomechanism of impact resistance in the woodpecker’s head and its application.” Literature review in Science China. Life sciences. 56(8): 715-719. https://www.researchgate.net/publication/248384092_Biomechanism_of_impact_resistance_in_the_woodpecker’s_head_and_its_application; Yirka, Bob. 2014. “Study reveals shock-absorbing ability of woodpecker beaks.” Phys.org. https://phys.org/news/2014-05-reveals-shock-absorbing-ability-woodpecker-beaks.html

Posted by Carol