Assessing the success of red-billed oxpecker translocations in KwaZulu-Natal

Red-billed oxpeckers (Buphagus erythrorhynchus) have a mutualistic relationship with large terrestrial mammals. This means that both animals benefit from the relationship; oxpeckers forage for food and hosts benefit from reduced parasite loads. Oxpeckers generally feed on ticks that are found on these animals, but also feed wounds, sweat and tears. They generally have preferences for which host they search for ticks: preferring species such as rhinoceros, giraffe, eland, buffalo and zebra.

14. Picture
Picture: A red-billed oxpecker fitted a registered SAFRING ring (right leg) and a colour ring (left leg).

Red-billed oxpeckers are secondary cavity nesters, so they are dependent on finding suitable holes in trees; either natural cavities or ones made by other birds and animals. They collect grass, dung and fur (that they pluck from animals) as nesting material. We observed an oxpecker plucking fur from an impala that was clearly irritated and annoyed with this. The impala kept moving its head to chase the bird away, however, the oxpecker kept ducking out of the impala’s reach. This continued until the oxpecker had filled its bill with fur when it flew off to build its nest. Red-billed oxpeckers sometimes use their host animals as platforms on which to conduct their breeding displays and mating. On one occasion, we witnessed a pair of oxpeckers mating on the back of a buffalo followed by plucking fur from it.

In southern Africa red-billed oxpeckers have had a drastic range reduction. This was caused by three main factors: their host species populations decreased, indiscriminate dipping of cattle with toxic dips, and the concomitant decreased food availability. Availability of cattle dips that are considered “oxpecker friendly” may reverse these trends in some areas.
An important conservation tool is translocation which is the intentional movement and release of animals to areas where they are locally extinct or have dwindling populations. Translocations aim to restore natural ecosystem functions or processes. A translocation is considered successful when the population is self-sustaining with breeding of released individuals and so persistence of the population. Until recently, red-billed oxpeckers were regarded as Near-threatened, however, this has recently changed and they are now listed as Least Concern. This can partly be attributed to the various translocations of oxpeckers that have occurred since the late 1980s. In particular the Endangered Wildlife Trust (EWT) has had a project which focused on reintroducing oxpeckers to where they were locally extinct in South Africa. Since the late 1980’s to date, EWT has translocated at least 1359 red-billed oxpeckers.

Consequently the current project is investigating the success of red-billed oxpeckers translocations and reintroductions. In particular we are investigating whether red-billed oxpeckers are breeding in the relocated areas and determining their persistence at translocation sites in KwaZulu-Natal (KZN) mainly.

The main objectives of the current project are to:
(1) Visit selected sites in KZN where oxpeckers were released and do an assessment. This includes recording number of oxpeckers, re-trapping as many birds as possible then releasing, and ringing individuals without ring bands.
(2) Determine whether translocations at the respective sites were successful or not.
(3) Determine if the oxpeckers have expanded their range from where they were released at the respective sites.
(4) Determine if the oxpeckers are nesting in their relocated sites.
(5) Map the oxpeckers’ current distribution in KZN and compare that with the range prior to reintroductions.

We are capturing red-billed oxpeckers using mist nets that surround an animal decoy. We made a decoy using a plastic barrel on a stand with a tanned zebra skin draped over it. A tanned zebra skin was chosen as we have had several sightings with of red-billed oxpeckers feeding off of zebra.

Capturing red-billed oxpeckers requires us to wake up at two o’clock in the morning in summer, set up the mist nets and decoy in the dark to be ready before sunrise. In some areas, we need a game ranger to escort us while we set up in the dark.

We have heard elephants in the nearby bush feeding and lions roaring less than a kilometer away. We have also seen how other animals react to the decoy that has legs flapping in the wind. For example, two zebra and a lone blue wildebeest stared and snorted at the decoy. After they found a “safe” route, they raced past the decoy then looked back at it from the other side.
Mist netting oxpeckers involves lots of waiting and patience. Sometimes red-billed oxpeckers tease us by sitting on top of our poles and nets and so avoid getting caught. However, those oxpeckers that are caught are measured and fitted with registered SAFRING rings and colour rings. Each ring has a specific series of numbers and serves as an identification tag for the bird when the bird is caught again:

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Picture: Measuring the tail length of a red-billed oxpecker.

Captured birds are checked for a brood patch to determine their breeding status . All this information helps determine when these birds moult, breed and how long they live for. A drop of blood is taken to determine the oxpecker’s sex and its relatedness to other individuals. The latter assists in determining extent of range expansion as the genetics of the founder populations are known. A feather sample is taken for isotope analysis. Ecto-parasites are collected to determine parasite load of the birds caught. We release the birds at their capture sites as soon as possible.
We conduct regular transect surveys to determine population estimates of oxpeckers at selected release sites. At all release sites we collect geographical co-ordinates of roost and breeding sites. We have found some red-billed oxpecker nests, some of which were not in trees. For example, we have found one nest in a black hollow pole and another nest in a fence post of a pig pen. It appears that red-billed oxpeckers are resourceful and make use of holes not only found in trees.

We also record the locations where oxpeckers are observed and on which animal they were feeding from. During our surveys, we have observed red-billed oxpeckers feeding from smaller animals, such as warthog and impala. We have also seen an oxpecker sit on a bushbuck that had wandered out into the open. However, the oxpecker was unable to search for ticks, as the bushbuck was trying to chase the bird off its back. We have seen red-billed oxpeckers with colour rings feeding off of zebra and other animals. We have also requested the public and surrounding communities’ involvement in the current study. We have corresponded via emails to farming communities and conservancies, requesting any current oxpecker activity or historical sightings. In addition, we would like to ask the readers to report any red-billed oxpecker sightings, paying special attention to any red-billed oxpeckers with colour rings. Please record the location coordinates, date of the sighting and number of birds seen and email this data to rynamay@gmail.com and downs@ukzn.ac.za

Maryna Jordaan (MSc Candidate)
Supervisor: Professor Colleen T. Downs
School of Life Sciences, University of KwaZulu-Natal,
Private Bag X01 Pietermaritzburg, 3209, South Africa

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