Monday, December 9, 2013

Oxpeckers (Africa Series)

Preferring their meals on the go, oxpeckers ride the back of a Cape Buffalo.  Travelling at a slow, lumbering pace, the Red-billed Oxpeckers are secure in their own safety, while providing a measure of security for the buffalo as well.  In exchange for a free ride, a lofty perch and a buffet of ticks, they alert their host to predators with loud hissing calls.

Yellow-billed Oxpeckers are gregarious, curious birds, entertaining to watch as they watch you back.

Comical in their habit of clinging to large mammals while gleaning their favorite food…ticks, they have a mutually beneficial relationship with large mammals like this eland.

Large mammals and even domesticated cattle often carry ticks on their hide.  Some of those ticks are difficult for the animal to remove by scratching, biting or licking.  The oxpecker benefits his host by eating ticks and is most likely why they put up with this interloper. 

 (Click on any picture to enlarge)

The oxpecker’s benevolence has been questioned though. Oxpeckers favor blood-gorged ticks that have already fed on their host, thereby only slightly benefiting the host animal.  They eat smaller ticks, lice and other parasites, too, but the question is; is the oxpecker after the tick or the blood?

Oxpeckers are known to lap up blood from open wounds and even enlarge old wounds in search of blood. For all the tick-cleaning benefit the oxpecker provides, does that make the oxpecker a blood sucking parasite in the process?  A fresh wound on this hippo’s back offers an oxpecker a small amount of blood at the hippo’s expense.

Since the bird is at least welcomed to search for insects on the mammal, it would stand to reason that the animal benefits by the oxpecker’s foraging. For example, this Red-billed Oxpecker scoured a giraffe’s neck in places where it’s doubtful the giraffe could reach alone.  

Elephants are one of the few mammals that discourage oxpeckers landing on them and will shoo them away.

It’s a gritty, pest-ridden world and some clean-up needs to be done. The bird and beast share an unusual relationship that's gone on uninterrupted for millions of years.   The question remains though, is it a relationship base on mutualism or parasitism?

In the vast savanna, where a hippopotamus is the tallest perch, a small group of oxpeckers gather to rest at sunset.  The oxpeckers will soon find shelter for the night in the trees. The hippo will forage on grasses throughout the night. He's quite likely to attract more biting ticks by morning, too.