Experiments have shown that Goldcrests are morphologically and behaviourally more specialized to forage in coniferous forest compared to the strikingly similar Firecrest. The species differ particularly in foraging speed and postures, which means that branches are exploited in different ways. Both the Firecrest and Goldcrest evolved from a common ancestor, but did so in different refuges dominated by differing floras and food regimes. The existing broad difference in habitat utilisation developed in allopatry and thus there is no need to invoke competition in the current areas of sympatry to explain the ecological differences between the two species (Leisler and Thaler 1982).
The Goldcrest also has much the same range and habitat preference as the Common Chiffchaff, and there is some evidence that high breeding densities of the Goldcrest depress the population of the warbler, although the converse is not true. There is no evidence that the species compete for territories, and in any case the Chiffchaff is 50% heavier than the Goldcrest. The Goldcrest may be out-competing the warbler for food, especially as the larger bird faces more competition from other insectivores, including other Phylloscopus warblers. Both birds occur in similar forests, but the Chiffchaff is found within 100 m (330 ft) of the forest edge, with the Goldcrest breeding deeper in the woodland (Tiainen et al. 1983).
It has been found, that migrating Goldcrests in the earlier stages of post-juvenile moult (high energy demands) had smaller energy reserves than birds in the later stages of the moult (lower energy demands), indicating a trade-off between energy reserves and moult in this species. Since migratory birds need large fat reserves to fuel energetically demanding flight and to buffer themselves against unpredictable re-fuelling possibilities and weather conditions, this indicates that birds which have completed their post-juvenile moult were better off than birds that migrate and moulted simultaneously (Merila 1997).
Reference List
- Leisler.B., & Thaler.E., (1982) Differences in morphology and foraging behaviour of the Goldcrest (Regulus regulus) and the Firecrest (Regulus ignicapillus). Annales Zoologici Fennici,, 19, 277-284.
- Merila.J., (1997) Fat Reserves and Moult Overlap in Goldcrests (Regulus regulus) – a Trade Off? Annales Zoologici Fennici,, 34, 229-234.
- Tiainen.J., Vickholm.M., Pakkala.T., Piiroinen.J., & Virolainen.E., (1983) “The habitat and spatial relations of breeding Phylloscopus warblers and the goldcrest (Regulus regulus) in southern Finland. Annales Zoologici Fennici, 20, 1-12.
