Nest Insulation in the European Robin (Erithacus Rubecula): Effects of Latitude and Construction Materials

Abstract

The various roles that birds' nests play are widely discussed and there is increasing interest in developing a better understanding of how they achieve these roles. The insulatory properties of nests have been investigated in a variety of songbird species and in some instances have been shown to relate to temperature and latitudinal variations. However, data are not available for a wide range of species. Here, we study the variations of the insulatory properties of European Robin nests in conjunction with the morphology and composition of materials. As well as describing these nests for the first time, we test the hypothesis that there is a latitudinal effect on nest insulation. Robin nests have a cup structure that is quite distinct, and easily separated, from the nest base. Although the cup and nest base shared similar construction materials discriminant analysis showed that they can be distinguished on the basis of their differing proportions of leaves. Unlike other songbirds of comparable size that nest in nestboxes, European Robins appear to be able to use plant-derived materials rather than animal-derived materials to effectively insulate their nests.

It’s not all about temperature: breeding success also affects nest design

“…For example, as latitude and/or altitude increases and mean temperatures decrease, European blackbirds (Turdus merula), American robins (Turdus migratorius) and common 'amakihis (Hemignathus virens virens) build heavier nests with thicker walls, which retain more heat (Crossman et al 2011;Kern and van Riper 1984;Mainwaring et al 2014a;Rohwer and Law 2010). A range of other species, for example, yellow warblers (Setophaga petechia), great tits (Parus major), blue tits (Cyanistes caeruleus) and European robins (Erithacus rubecula) change which materials they put in their nest, and use better, and more, insulatory materials (for example, feathers, animal fur) in cooler environments at higher latitudes and altitudes (Cerezo and Deeming 2016;Crossman et al 2011;Mainwaring et al 2012). Nest-site selection may also vary between populations, for example, northern orioles (Icterus galbula) in cooler locations construct nests higher in the canopy than do orioles in warmer locations, perhaps because building a nest higher in the canopy exposes the nest to more solar radiation and, therefore, reduces cooling of eggs and chicks (Schaefer 1976).…”

Composition of nests constructed by species in the Motacillidae, Sylviidae and Prunellidae

“…Different regions within avian nests have previously been identified by the types of material present within specific parts of the nest and have been suggested to perform distinct functions. 1,7,11,16,30,61 Choice of nest components and specific placement of components in nest regions suggest that the bird may have an awareness of the materials' properties and are using them in response to the localised physical environmental conditions they experience. 11,62,63 The results of our study provide empirical support for the notion that nest materials can be used to create recognisable nest regions 30 but the functional properties of these distinguishing features have yet to be fully explored.…”

“…11,62,63 The results of our study provide empirical support for the notion that nest materials can be used to create recognisable nest regions 30 but the functional properties of these distinguishing features have yet to be fully explored. Moss is more common in the outer base and sides of nests of many bird species, particularly those breeding in cavities, 16,35,32,64 although it is also present in nests built in the open. 16,30 Although previously considered to be involved in moisture absorption, 65 moss may provide structural support in the nest wall 64 or may possibly be used in camouflaging the nest.…”

“…60 This report has increased the published dataset by six new species bringing the current total to 31 passerine species of mainly European origin. 3,16,30 While this is a marked expansion of species coverage since 2010, this is far short of the 5000 passerine species so we remain largely ignorant of the composition of most passerine nests and detailed composition of non-passerine nests has not been reported. This is hampering our understanding of how inter-specific variation in the materials affects the various functions of a nest.…”

“…4,10,12,14,15 The amount of insulating material present in the nest has been linked to the successful incubation and survival of nestlings in many species. 6,7,12,16 The presence of feathers within a nest is associated with good insulation, 17 slower rates of cooling of eggs, [18][19] and increased nestling growth rate in passerines 20 but experimental heating of nests had no significant effect on the numbers of feathers found in nests of the tree swallow (Tachycineta bicolor). 21 The bird nest is a crucial element of reproduction, especially for incubation, and it can be assumed that the ecological and environmental conditions required to reproduce are species-specific.…”