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Afrikaanse Inligting
Sugarbird Poisoning
Regarding the recent article on Sugarbird Poisoning entitled
"Bittersweet" in the August / September 2003 issue of Africa Birds and Birding:
This was first identified as a problem in 1987 (Rebelo 1987 "Management implications" in Rebelo "A preliminary synthesis of pollination biology in the Cape Flora". SANSPR 141: (page 198)):
Out of 12 farmers approached at a protea farmers meeting at Elsenberg Agricultural College <regarding unconfirmed reports of farmers shooting Sugarbirds in protea orchards during 1986>, 7 knew that poisoning was more effective, and that a stick with a treated flowerhead above the orchard proteas was effective in attracting birds within sight and solving the problem.
Because only a very few flowerheads need be treated, the process is undetectable except by field inspections during flowering time. Without field officers checking this up, this poisoning will be utterly undetectable. However, to be effective, poisoned flowerheads should be noticeably above the general level of other proteas in orchards (territorial birds <in both breeding and feeding territories> scan their domain from high perches, making this a very effective means of eliminating birds) and thus quite visible to casual inspection. Once detected, it should not be hard to find dead birds to obtain a conviction, assuming that one could get permission to search the orchards.
(I should point out, that over the past 12 years of Protea Atlassing I have unannounced been through hundreds of protea orchards and thousands of kilometres of veld and only noticed this practice once (and bird liming once as well). These were not reported as they would have jeopardized access to mountains. As it is now 6 years on, so no further action will be taken.)
Damage of flowerheads by Sugarbirds should not be a general problem, although it is not known if farmers see it this way. It only really applies to Protea magnifica and Protea grandiceps, (and Protea speciosa and Protea stokoei which are not farmed) which have delicate bracts which are easily scarred. Whereas Protea grandiceps is currently out of fashion, Protea magnifica is a major money spinner. Unfortunately for the birds this species flowers during the peak nectar dearth in the western Cape and is possibly the major nectar source for Sugarbirds during this food crunch. Impacts of poisoning during this period could thus have a major impact on overall population sizes. (However, birds could just as well be moving eastwards, we have no idea of what movements Sugarbirds undertake, in which case the effects on overall population size of the species will be far less). Also unfortunately, many of the modern hybrids also have the silky involucral bracts currently in fashion and as more cultivars are cultivated, this problem will become larger. Similarly, the Christmas market is driving cultivar selection, and this seasonal trend will attract significant numbers of Sugarbirds. In addition, these hybrids do not need to be planted at high altitudes (like Protea magnifica) and so are not exposed to frost, leaving the birds as the major problem (other than insect loads, which can be eliminated using approved insecticides) to export flower production. Manually enclosing flowerheads is thus not so economically attractive and other methods may be more appealing.
It is argued that frost is a major reason for manually closing up blooms, which keeps off birds as well. This only really applies to Protea magnifica in the wild and orchards at high altitudes or valley bottoms - a minority of Protea orchards. It is also argued that birds do not visit flowerheads until they are open. Unfortunately birds do forcibly visit young flowerheads, especially during periods of nectar dearth (such as in summer and when all open flowerheads have been picked). Nectar secretion appears to start just before flowerheads open, and the birds soon learn to look for it. It must also be noted that farmers get better prices for perfect blooms even locally, and the problem may not be confined to exported blooms.
Because birds are so vagrant it will not be valid to compare old records to determine population changes. Local bird numbers depend not only on local resources, but also on competing resources in other areas, and with fire patterns, climate variation and agricultural expansion bird movements may be totally unpredictable. The species' populations could be drastically reduced before a decline could be confirmed. Without a detailed study on Sugarbird movements it will be impossible to determine if poisoning will have a serious effect on total Sugarbird numbers. So, if Sugarbird populations have drastically declined over the past decade, we have no way of knowing it, let alone proving it, let alone attributing it to poisoning.
Lastly, there was a throwaway line in the article which is just as disconcerting as the poisoning. Briefly, it was (is) recommended that substandard and old flowerheads be removed from bushes to control levels of pests. This is all very well and true in agricultural orchards (and it means that the plants can reallocate resources to growth rather than flowerheads and seedheads), but large numbers of proteas are picked from the veld. This practice effectively removes the fireproof seedheads and the seedbank from the area. Drastic population declines of wild Protea magnifica in the Swartruggens/Baviaansberg have occurred over the last decade due to this practice, and some magnificent stands are now lost. This despite guidelines of harvesting rates for sustainable utilization of wild proteas being available, it being well known that fires are unpredictable and that - for proteas - in situ seedheads are an easily assessed measure of seedbank size at any time. It goes without saying that for wild populations of proteas, Sugarbirds are a major (but not indispensable) "source" of seeds.
Tony Rebelo
Protea Atlas Project
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