(The text below was scanned in so I hope the OCR software got everything right)
Why do warthogs drop to their knees to feed?
This is more common in winter when most of their food is underground and needs to be dug up. The disc at the end of the nose and the tushes (tusks) are used. The digging is more easily accomplished while the warthogs are on their knees, as more leverage and resultant digging efficiency are obtained, especially in harder soils.
Warthogs are the only 'pigs' in Africa to exhibit this phenomenon, and the reason for it may lie in the fact that they are the only ones that live and mostly graze in open savannah. The other species, like bushpig, live in the forest and generally have enough food in the form of fallen fruits, and other goods in the winter. Rooting at this time takes up less of their day, and the litter and soil are generally softer than on the sunbaked open areas where warthogs live. In winter warthogs rely almost entirely on rooting to find adequate and sufficient food, and spend most of their time doing this. This puts a strain on the animal, which is alleviated by dropping to the knees and resting while rooting, and possibly creates greater leverage with which to dig in hard soils. Thus the knees have developed heavy callouses. Warthogs, having to work relatively harder to obtain food than their forest relatives, spend a lot of time on their knees for comfort and convenience, if not out of necessity. One could then ask why they do not have much shorter front legs to facilitate this strategy, but such a feature would make them vulnerable to attack and less agile in escape.
Why do bats hang upside down?
Essentially because their legs are too weak to hold their body weight. This has occurred as a result of adaptations to fill their particular niche as mammals. Bats are the only mammals that fly. As in birds, weight-saving mechanisms evolve to make flight possible. Most birds have hollow bones but have minimal reduction (in most species) of the legs as they need them for perching and walking about in search of food. Bats have followed a different route altogether. Rather than having feathers (which are modified scales that hint at birds' reptilian ancestors),
they have developed extensive but light, membranous wings, have kept the solid bones, but have reduced on the one thing that was not of prime importance - their legs! Because most bats are feeders of aerial insects which they catch on the wing, they can afford this, and so have adapted their wings (forelimbs) to have claws (hooks). Because birds have occupied most of the niches for flying, bats compete by hunting at night (when most birds are inactive) and use their claws to hang rather than perch. The legs in insect-eating varieties are, therefore, rudimentary and not capable of holding the animal's weight (cumbersome shuffling being the only movement of these limbs). Fruit-eating bats still need some locomotive ability of the legs to aid in clambering around for fruit - but they are nowhere near as agile as birds.
Why do oxpeckers sit on mammals?
Why do comb ducks (knob-billed ducks) have knob bills?
Why do hamerkops have such big nests?
These are just some of the questions answered in a new book I bought last night called "Beat about the bush: Animals and birds
Author: Trevor Carnaby
I bought it at Wordsworth for R277.00