WOODPECKERS: CHARACTERISTICS, HABITAT, REPRODUCTION, NUTRITION - BIOLOGY - 2024

The woodpeckers are birds characterized by being climbing trees and peck peel. These birds make up the Picidae family (Piciforme order) with about 218 described species. This family of birds is cosmopolitan and is distributed in all climates, except for the polar regions, Australia and Madagascar.

Its members also receive other names such as carpenters, telegraphers, woodpeckers, among others, which refer to their habit of chopping trees in search of insects.

Common Florida Woodpecker (Dryocopus pileatus) By Kate Perez

Woodpeckers are a family of birds with a relatively homogeneous ecology. They play an important role in forest ecosystems as a controller of insect pests and for their contribution to the health of trees.

The feeding strategies and their surprising ability to extract insects from the trunks, has allowed them to occupy a great variety of habitats. In addition, they are able to maintain high levels of sympatry due to the distribution of resources.

Woodpeckers have acquired morphological modifications that make up the characteristics shared by all members of the family (synapomorphies).

Among these characteristics is its peculiar long tongue covered with spines that can extend out of the mouth and an elongated hyoid apparatus. They also have elongated sub-lingual thyroid glands, thickened skull, rigid rectrices, and the nasal glands weakly enter the orbits.

General characteristics

These birds can weigh between 8 grams (in the case of woodpeckers of the genus Sasia), up to more than 500 grams in some genera such as Mulleripicus and Campephilus. In addition, their body length varies between 20 and 56 cm.

These birds have zygodactyl legs with fingers 2 and 3 pointing in front and fingers 1 and 4 back, giving them excellent grip and stability when climbing the trunks. The tail feathers (rectrices) are stiff and pointed at the end, so that it serves as a fulcrum when they climb trees in search of food.

The coloration varies greatly among woodpecker species, although many exhibit red and beige feathers in the head area, with a reddish and orange crest on the crown being common.

Head and tongue

Woodpeckers are very well adapted to their pecking and tree climbing habits. These animals must withstand the impact of a peck that occurs at speeds of up to 7 meters per second, with around 20 pecks per second.

The characteristics of the skull and tongue of carpenters allow them to carry out these activities without suffering damage or concussions. The skull is especially thick to absorb shock.

These birds have arcuate mesocranial bones with two longitudinal ridges that extend to the posterior region of the skull. This allows them to withstand the vibrations generated by pecking the wood of the trees.

Woodpeckers also have a specialized tongue to collect insect larvae from inside the bark of trees. This is long, elastic and with hook-shaped structures at the end.

These hooks, together with the production of a highly viscous and adherent saliva, allow them to introduce it into the drilled cavities to reach and fix their prey.

Woodpecker Tongues Outline By Popular Science Monthly Volume 49

Hyoid apparatus

Another important adaptation for pecking is the hyoid apparatus. This includes the bones of the tongue and connective tissue. In all birds, this apparatus consists of five distinctive bones: paraglossal, basihial, urohial, paired ceratobranchial, and paired epibranchial.

Unlike the rest of the birds, the epibranchial bone in the woodpeckers is very long, representing about 60% of the total length of the hyoid bones. The epibranchial extends to the supraorbital crest between the eyes. Also, in the Picidae family, the urohial bone is absent.

The hyoid apparatus of carpenters extends around the skull, from the rostral, below the beak, to the caudal at the top and terminal part of the skull.

The characteristics of this structure give it the ability to reduce the impact of pecking by absorbing part of the energy generated during said activity. This system works like a seat belt that helps prevent brain damage, reducing compression and tension stresses by up to 40%.

Habitat and distribution

Japanese Pygmy Woodpecker (Dendrocopos kisuki) By Photo by Laitche

The birds of the Picidae family have a cosmopolitan distribution, with peaks of wealth in the Neotropics and Southeast Asia. These regions concentrate approximately half of the species described. However, this family does not cross the Wallace line and is absent in the southern region.

Most isolated islands lack species of woodpeckers. However, for the Antilles more than 12 species have been reported with some endemic genera from various archipelagos. In Cuba, these birds are represented by more than 5 species.

Woodpeckers are generally sedentary and not very dispersive. The geographic range of woodpeckers tends to decrease as species richness increases, with species found at high latitudes being the most widely distributed.

In the Picidae, an estimator of species richness is the area of ​​the geographic region. So the regions with less area have greater wealth and show more endemisms.

Woodpeckers inhabit all types of forests, being virtually absent in treeless regions such as deserts, tundras, and alpine areas.

Reproduction

Male Woodpecker (Melanerpes radiolatus) building a nest By Charles J Sharp

In woodpeckers, monogamy is the general trend, with a pair of birds often remaining together for most of their lives. However, in many species the males and females are only found during the reproductive season.

Woodpeckers often nest in tree holes that they dig by pecking themselves and in caves on cliffs. Nests are sometimes built by both sexes, although it is generally the male who does most of the construction.

The female lays 2 to 8 white eggs. Incubation lasts about two weeks and the chicks take between 18 days and a month to fledge. Both the male and female take care of and feed the chicks.

The incubation time of these birds is one of the shortest that has been recorded. Likewise, the time that the chicks require to develop and leave the nest (fledging) is relatively long compared to the incubation period.

Some studies suggest that nest characteristics and parental care make chicks very secure, which is related to the long time it takes for them to fledge.

Nutrition

The diet of the more specialized woodpeckers is mainly insectivorous. However, many species are capable of consuming a great variety of fruits, seeds and even sap, thus having a much more diversified diet in the habitats they occupy.

Some of these birds mainly consume hymenopterans of the Formicidae family that establish their nests under the bark of trees. In addition, they supplement their diet with larvae of Hemiptera, Coleoptera and Lepidoptera that also make galleries, mainly in hollow trunks. Other species specialize in consuming beetle larvae.

Several Neotropical species also supplement their insectivorous diet with fruits from more than 15 species of trees. Contrary to expectations, some of these birds show a higher consumption of fruits in the seasons of scarcity of the same.

This is probably due to the fact that during this time the breeding period occurs and the chicks require a greater amount of nutrients.

Woodpecker feeding on fruits (Melanerpes rubricapillus rubricapillus) By Charles J Sharp

Other species are acorn gatherers, which they store individually in small holes that they generally open in trees near their refuge. This is a strategy to manage to survive the winter season.

Behavior

The woodpecker family shows a range of social relationships ranging from individuals who adopt a solitary life after leaving the nest, through individuals who live in pairs for a long time, to stable social groupings.

Several species of this family can exhibit social behavior in the selection of nesting areas and even community nesting activities. Some females can place their eggs in the same nest and also participate in the care and feeding of them without discriminating the young from the other females.

The drumming of these birds without any intention of searching for food, constitutes in the reproductive season a form of exhibition by the males for the courtship of the females. On the other hand, it can also constitute a behavior of delimitation of territory in those areas or stations in which resources are not abundant.

Search for food

Much of the woodpecker species behave very similarly to other insectivorous birds of the order passerines. Rather, these birds forage for insects among foliage and trunks rather than locating it by using their beaks and tongue among the bark of trees.

These birds are quite efficient foragers. Once they locate places where food is available, they constantly frequent them. On the other hand, those places with little supply, or those in which highly nutritious food is not available are abandoned and little frequented.

Woodpeckers' beaks are straight, hard, and chisel-shaped. Anchored to a tree trunk with its tail serving as a clamp, the woodpecker delivers quick, powerful strokes to dig cavities and expose burrows of wood-boring insects. It then uses its long, flexible barbed tongue to catch these insects in its galleries.

Ecological paper

Holes made by a carpenter By Rhododendrites

Carpenters play an important ecological role within forests. The excavations carried out in the trunks for feeding and nest building activities are of relevant importance in the decomposition processes of the trees.

Additionally, some researchers suggest that these birds have a significant role as dispersal vectors for wood-living fungi.

On the other hand, woodpeckers have been suggested as indicators of forest biodiversity. This is due to the strong association that these birds have with forest environments and their sensitivity to structural changes and composition of tree species.

References

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