Zebra black and white at birth. Plains and mountain zebra foals are protected by their mothers, as well as the head stallion and the other mares in their group. Grévy's zebra foals have only their mother as a regular protector, since, as noted above, Grévy's zebra groups often disband after a few months. Attempts have been made to train zebras for riding, since they have better resistance than horses to African diseases. While occasionally successful, most of these attempts failed due to the zebra's more unpredictable nature and tendency to panic under stress. For this reason, zebra-mules or zebroids (crosses between
Zebra crossing cross the road (see jaywalking). In New Zealand, motorists are required to give way to pedestrians. Pedestrians wishing to cross the road within 20 metres of a crossing facility (which includes zebra crossings) must use a crossing facility. In Australia, raised zebra crossings are sometimes called wombat crossings. A 1998 Swedish study by A Várhelyi at Lund University found that the frequency of giving way at zebra crossings was 5% and drivers typically did not observe the law concerning speed behaviour at the zebra crossing. Speed behaviour in encounters (148 observations), non-encounters with pedestrian presence (642 observations) and situations without