The main function of bird nests is to provide shelter for eggs and nestlings in order to support optimal offspring development. While this basic condition applies to all nests, an enormous constructional variety in nests has evolved. Regarding its thermal properties, the avian nest construction generally represents a compromise between heat conservation,heat dissipation, and protection from external heat.
The Ethiopian Bush-crow is an endemic Ethiopian bird species which has a very small and climatically distinct range that is cooler, dryer and more seasonal than the surrounding areas. Bush-crows build large domed nests made of thorny twigs with comparatively thick walls and a soil-lined bottom. In a preliminary study* we studied the thermal properties of a bush-crow nest with the aid of IR thermography. Our results show that there was no heat emission in the early morning and that nest surface temperatures clearly corresponded to the temperature changes during the day. Therefore we hypothesise that the nest construction provides substantial thermal insulation during the night time and presumably also delays temperature increase in the internal nesting chamber during the day time. We suggest that the bush-crow’s specific nest construction may have contributed to its persistence in the climatically unique south Ethiopian conditions.
* Töpfer, T. & K. Gedeon 2012: The construction and thermal insulation of Ethiopian Bush-crow (Zavattariornis stresemanni) nests: a prelimary study. Avian Biology Research 5 (4): 198-202.
 |
| Thermographic image of a bush-crow nest just before sunrise (a) and at noon (b). |
