Not African elephants but I once got to watch two bestie female Asian elephants get reunited after about 2 weeks apart. They knew for MILES. But the happy, thunderous sounds from even about a mile away were so joyous and unmistakeable.

Also got to witness a bull and his favorite female reunited after about a year apart. Less sound, but OMG the trunk touching, the food sharing, seriously one of the most beautiful love stories I have ever seen. Made very bittersweet by the fact that she couldn't get pregnant by him and her former bestie, who had a 2 year old son by him, lived right across the road and also had to witness it.