Woodpeckers: Miracle Birds Designed to Peck Wood
Woodpeckers (family Picidae) are found almost everywhere on the continents except extreme polar regions. Most species live in forests or woodland habitats, and many of the about 30 genera and 214 known species are now threatened due to loss of habitat or habitat fragmentation. The smallest woodpecker is the Bar-breasted Piculet (seven grams and eight cm tall) and the largest is the Imperial Woodpecker (average over 600g (1.3 lb) and 58 cm (23 inches) tall. Some species exhibit differences in appearance of the sexes such as body size, weight and bill length. In such cases, the males are larger.
Most species possess predominantly white, black and brown, green and red plumage and patches of red and yellow on their heads and bellies. The dark areas of plumage often reflect bright colours in direct light. The males of many woodpecker species have more prominent red or yellow head markings than do the less showy brown or gray females. Woodpeckers are active during the day, roosting at night inside tree holes and the roost for most species becomes the nest during breeding season.
They are best known for their strong bills used for rapid drilling in trees, and their long sticky tongues for extracting food from the holes. Almost every part of the woodpecker’s anatomy is designed for the sole purpose of boring into wood. The bill’s chisel-like tip is kept sharp by the bird’s pecking action. It pecks so hard and fast that its head becomes a blur to observers. The long sticky tongues possess bristles that aid in grabbing and extracting insects deep within the holes that they make in trees.
The impact with the tree causes the head to decelerate at a rate fully 1,000 times the force of gravitational acceleration (Walker, 2007, p. 5). In contrast to other birds, the woodpecker’s beak and skull are joined by spongy, elastic connective tissue designed to function as a highly effective shock absorber. The many features designed to protect their brain from damage caused by the repeated rapid deceleration include a small brain protected by a thick skull, shock-absorbing muscles at the base of its beak, the orientation of the brain within the skull to maximize the area of contact between the brain and the skull, and the short duration of contact. The “woodpecker’s brain is attached so well to the skull that there is little residual movement or oscillation of the brain just after the impact and no chance for the tissue connecting the skull and brain to tear” (Walker, J. 2007. The Flying Circus of Physics. 2nd Edition. New York: Wiley p. 5).
Male woodpeckers strike the tree as often as 12,000 times a day. About a millisecond before contact with wood, a tough lid-like membrane closes, shielding the eye from pieces of wood bouncing off of the tree. When closed, this membrane also helps to hold their eyeballs in place. The membrane “eyelid” acts like a seat belt to keep the eye from literally popping out of the head, an impact that would tear the eye’s retina. The slit-like nostrils are covered with special feathers to protect them from flying woodchips.
After hammering a hole into the wood, their prey is excavated by their long sticky barbed tongue. Their tongue travels in the head under the jaw, around the back of the head and then on top of their brain and is anchored in the right nostril. The left nostril remains free for breathing. Their excavate ability also allows woodpeckers to obtain tree sap, an important source of food for species such as the sapsuckers (genus Sphyrapicus).
Their pecking behavior is also used to communicate with other woodpeckers. Actually, many of the breeding, signaling and foraging behaviors of woodpeckers involve drumming and hammering with their very hard and sharply pointed beak.
To locate insects they move up, down, and around trees listening for the faint sounds of insects. This acute sense of hearing enables them to locate insect movements, or the hollow sound made by insect boring holes. When a relevant sound is detected they start to hammer a hole for their prey.
Woodpeckers have short strong legs typical of birds that regularly forage on trunks and specialized feet that consist of four toes. To effectively grasp the tree limbs and trunks the first and the fourth toes face frontward, and the second and third toes face backward, producing a gripping force similar to a pair of ice tongs. They can walk vertically up a tree trunk to forage for food or nest excavation. When the bird perches on vertical surfaces its feet work together to support it, and the stiffened tail acts like a brace to steady the bird.
True woodpeckers, subfamily Picinae, live mostly in wooded areas. They reach their greatest diversity in tropical rainforests, but exist in almost all suitable habitats, including woodlands, savannahs, scrublands, bamboo-forests and even grasslands and deserts. These habitats are often occupied where a small number of trees exist, or where, in the case of desert species like the Gila Woodpecker, tall cacti are located for breeding and roosting holes. Many species remain in the same area year-round while others travel great distances from their breeding habitats to their wintering grounds.
Woodpeckers range from highly aggressive antisocial solitary species to those that live in groups. Group-living species tend to be communal group breeders. They hammer on everything from utility poles to metal roofs to make noise to attract mates and to warn other woodpeckers to keep out of their territory (Peck, G. K. 1989 Woodpeckers. Smart Apple Media. p. 18).
The woodpecker diet consists mainly of insects, grubs, and sap taken from living and dead trees, along with fruit and nuts. Their major ecological role includes keeping trees healthy by preventing mass insect infestations. Although noted for their ability to acquire wood-boring grubs by using their bills for hammering, the family diet is flexible, and many species are both highly omnivorous and opportunistic. This is a problem for Darwinism because woodpeckers do not require their complex pecking machinery to survive. Their most common insect prey, beetles and their grubs, ants, termites, spiders, and even caterpillars, may be obtained by scavenging, thus no need exists to excavate them from trees by pecking on wood.
Members of Picidae are typically monogamous, and a pair will work together to build the nest, incubate the eggs, and raise their young. Woodpeckers excavate their own nests, which is usually lined by the wood chips produced as the hole was made. Many woodpecker species excavate one hole per breeding season, which can require about a month in living trees. Their abandoned holes are used by other birds and mammals called secondary cavity nesters. Because nesting holes are in great demand by other cavity nesters, woodpeckers face competition for the nesting sites they excavate from the moment the hole becomes usable. The red-crowned Woodpecker digs its nest in the underside of a small branch, which reduces the chance that a larger species will take it over.
In most species the male does most of the nest excavation and takes the night shift to incubate the eggs and the female takes the day shift. A nest usually consists of 2-5 round white eggs. As cavity nesters, their eggs do not need to be camouflaged, and their white color helps the parents to see them in dim light. The eggs are incubated for about 11–14 days before the chicks are hatched and after about 20 to 40 days the young are ready to leave the nest. Until they do, the parents swallow insects that are stored in their food storage sack called a crop located in their throat. They then bring the food up to feed their young.
The evolution of woodpeckers has long perplexed Darwinists. If the woodpecker’s complex pecking machine evolved, it had to begin evolving from some existing structure. What made the first “woodpecker” (or would be woodpecker) decide to peck wood? It was not necessary for him to survive, and millions of other birds effectively obtain food simply by picking it off of the ground, or by consuming insects crawling on trees, flying in the air, or floating on the surface of water. Pecking wood would be useless until most of the complex system described above was perfected well enough to obtain food by this unusual means.
Until its acute hearing evolved, how could the first woodpecker determine there was food inside a tree? He could not see it, and could not hear it until his highly acute hearing evolved. Until he evolved the shock-absorbing cartilage between his beak and his head, and his head was thicker than other birds, and his beak stronger, longer, and sharper, pecking would be lethal. Furthermore, until his tail feathers had molted in a specific order he could not prop himself up to peck, and until his tongue was more than a little short thing inside his beak he could not fetch prey in the holes he pecked.
No fossil evidence exists to support the evolution of woodpeckers, and all known fossils, including the oldest so far discovered, are of modern woodpeckers. The earliest known modern picids, clearly woodpeckers, are dated by evolutionists back to the upper Oligocene (said to be about 25 million years ago) (Cracraft and Morony, 1969. American Museum Novitates 2400:1-8 Dec. 30). At this time in history woodpeckers were already widely distributed in both America and Europe. Because the earliest known fossils are all modern woodpeckers, evolutionists hypothesize that they must have first evolved long before this, as early as 50 million years ago, but if so where is the evidence?
The modern woodpecker subfamilies are considered rather young by comparison. Until the mid-Miocene (10-15 million years ago), all picids were small or mid-sized birds similar to a mixture between a piculet and a wryneck. A feather found in Dominican Republic amber dated to about 25 million years ago indicates the earliest known woodpeckers, called Nesoctitinae, were already modern woodpeckers. So the next time you see a woodpecker, or hear their distinctive tap tapping on local trees, be sure to reflect how remarkable and unique this bird family is.
Subscribe to Dialogue