The Use of Aromatic Plants in Cape Sparrow Nests
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1 2 3 4 5 The use of aromatic plants in Cape Sparrow nests 6 7 8 Text by Sue Milton & Richard Dean 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 FITZPATRICK INSTITUTE 50 n general, birds are very particular about The outer structure of the nest is a mass of A female Cape Sparrow at 51 the materials they select for nest building interlocking twigs bound together with vari- her untidy, but carefully 52 Iand the care and attention they pay to ous types of twine. In natural Karoo vegeta- constructed nest. 53 their nest construction. So at first glance the tion, where Cape Sparrows often locate their 54 rather messy-looking ball nests of the Cape nests in thorny trees along dry river beds, the 55 Sparrow Passer melanurus are surprising as they outer wall of the nest is usually built with 56 appear to have been built with little discrimi- flowerheads of the ‘peperbossie’ Lepidium afri- 57 nation. But on closer inspection it becomes canum mixed with white woolly strands of 58 evident that every part of the structure has ‘voëltjienes’ Galium tomentosum. The inside of 59 been selected for properties such as flexibility, the nest is lined with all sorts of soft material 60 interlocking projections, softness, colour and such as seeds of ‘kapokbossies’ (Eriocephalus 61 even smell. species), feathers, hair and wool. All Cape 62 FEBRUARY/MARCH 1999 CAPE SPARROW NESTS 37 1 1 2 When scented green plants were experimental- plants, but we strongly suspect that the behav- 2 3 ly removed from European Starling nests, the iour has benefits for chick health. Our evidence 3 4 numbers of parasitic mites in the nests comes not from observations of sparrow fledg- 4 5 increased a hundred fold. lings, but from information on the uses of 5 6 Quite apart from parasite control, aromatic Helichrysum species in African traditional medi- 6 7 plants may confer health benefits on fledgling cine and of thyme in European tradi tional 7 8 birds. A paper presented at the International medicine to treat wounds and respiratory 8 9 Ornithological Conference in Durban in 1998 infections, and to rid the body of parasitic 9 10 showed that aromatic plants increased the hae- worms. The medicinal powers of these herbs 10 11 matocrit levels in the blood of fledgling European have nothing to do with magic or superstition, 11 12 Starlings, improving immunity to diseases. but derive from antibiotic and anti-fungal chem- 12 13 Collecting aromatic plants is part of the court- icals contained in the volatile oils that give the 13 14 ship display of European Starlings and takes plants their characteristic aromas. 14 15 place during pair formation and nest lining, but Through trial and error over thousands of 15 16 stops when the first egg is laid. These starlings years birds and people have learned which 16 17 select suitable plants by smell, apparently plants have medicinal value and have come to 17 18 matching the odour of the plants that they associate disinfectant properties with certain 18 19 examine as potential nest material to that of aromas. So effective is the use of taste or smell 19 20 the nest in which they were raised. Significantly, to identify medicinal plants that birds and 20 21 the olfactory sense of European Starlings is people alike can add unfamiliar and foreign 21 22 Right A Cape Sparrow nest enhanced during the breeding season. plant species to their pharmacopoeia by match- 22 23 in a favoured site in a Birds that maintain nests throughout the ing the new aroma with that of more familiar 23 24 sweet-thorn tree. year and roost in their nests when not breed- plants. It is quite likely that birds are already 24 PETER STEYN ing, and birds that make use of second-hand using medicinal plants whose properties are as 25 grey ‘wolbossie’ out of 10 000 plants when we tree cavities rather than chipping out their own yet undiscovered by people. In the same way 26 searched surrounding gardens, vacant lots and nest holes, probably suffer more from parasites that traditional medicinal knowledge has been 27 the hillside where the sparrows foraged. and infectious diseases than birds that build the basis for the development of modern medi- 28 Our curiosity now awakened, we examined their own nests and use nests for incubation cines for treating infection, relieving pain and 29 other Cape Sparrow nests in the village and in only. One would therefore expect Sociable treating heart and digestive problems, so obser- 30 natural habitats in surrounding Karoo veld, Weavers, waxbills, penduline tits, woodhoopo- vations on the use of plants by birds could lead 31 and found that almost all of them included es and many of the cavity-nesting African star- to the discovery of compounds with curative 32 some aromatic plants such as ‘bergankerkaroo’ lings to usearomatic plants in their nests. We properties new to human medicine. 33 Helichrysum rosum, ‘vaaltee’ Leysera tenella, and can find no written records that these birds 34 S.J. MILTON 25 Above A Cape Sparrow nest ‘stinkkruid’ Pentzia pilulifera in their nest lin- incorporate green plants in their nest linings, If you have observations about the use of aromatic 35 26 sliced lengthways through Sparrow nests follow this general design, ings. Moreover, Cape Sparrows were not the but look forward to hearing from others who plants in sparrow nests, Sue Milton and Richard 36 27 the hollow centre to show except that along roadsides and in villages the only birds to collect fresh sprigs of thyme, might have noticed this behaviour. Dean can be contacted at their respective e-mail 37 28 the nest lining. The woolly, sparrows improvise by using man-made fibres camphor or curry-scented plants as nest mate- At present we know too little about the behav- addresses: [email protected] 38 29 grey-leaved twigs belong to such as string, fabric and carpet sweepings. rial. We have found these ‘smelly’ plants in iour of the Cape Sparrow to say how, when or [email protected] 39 30 the aromatic ‘wolbossie’. When a pair of Cape Sparrows nested on our nests of such diverse species as Grey-headed why it lines its nest with pungent-smelling 40 31 veranda in the Karoo village of Prince Albert, Sparrow, Namaqua Prinia, Chat Flycatcher, 41 32 we noticed that as a final touch in the nest- Fiscal Shrike and White-throated Canary. In 42 33 building operation the sparrows carried sprigs some instances the plant use may have been 43 34 of fresh green plants into their nest. When the entirely by chance, but in the case of the Cape 44 35 fledglings left, we opened up the nest and Sparrow it is so consistent that there must be a 45 36 found that the inner lining included large good reason – some real benefit to the birds. 46 37 quantities (20–60 per cent) of aromatic leaves The function of green aromatic plants used 47 38 and shoots. These were mainly ‘wolbossie’ by African passerine birds has never been 48 39 Helichrysum pumilio, an indigenous aromatic explored, but observations and experiments 49 40 herb, and thyme Thymus vulgaris, the European with European Starlings and Great Tits in 50 41 culinary herb. Although Cape Sparrows in both Europe suggest that the use of strong-smelling 51 42 rangelands and village gardens have a wide plants in nest linings improves fledgling health 52 43 variety of plants to choose from, it appears that or survival. Physiologists, parasitologists and 53 44 they intentionally select relatively uncommon, pharmacologists are still arguing about how 54 45 aromatic species which they invariably collect this works, and there may be more than one 55 46 as freshly-picked green material. We have since reason why birds collect aromatic plants. Some 56 47 seen Cape Sparrows breaking off stems of plants contain volatile compounds that are 57 48 thyme and taking these to their nests. The released when the plant is warmed by the incu- 58 49 selection of this herb and of ‘wolbossie’ for nest bating bird. The chemicals emitted adversely The male Cape Sparrow. The 59 50 lining could not have been by chance, because affect moulting and breeding in parasitic mites, behaviour of this abundant 60 51 neither was very abundant near the Cape and this improves nestling survival by reducing resident clearly deserves 61 52 Sparrow’s nest. In fact we found only one little the numbers of blood-sucking ectoparasites. more in-depth study. 62 ALBERT FRONEMAN 38 CAPE SPARROW NESTS AFRICA – BIRDS & BIRDING FEBRUARY/MARCH 1999 CAPE SPARROW NESTS 39.