TY - JOUR
T1 - Background matching and evolution of cryptic colours of selected passerines in deciduous woodlands
AU - Bursell, Jens
AU - Dyck, Jan
PY - 2003
Y1 - 2003
N2 - Most drab plumage colours are probably cryptic. Crypsis (camouflage) occurs when thecolour of a significant part of the plumage is similar to the colour of a significant part ofthe background against which the prey bird may be detected by a potential predator. Inthis study we compare back colours of tits and associated species with colourbackgrounds in their habitat during a four-month period in winter. We test thehypothesis that in some of the species back colour is similar to one of the backgroundcolours. In addition to colour backgrounds, microhabitats and tree species were alsorecorded. Great Tit Parus major, Nuthatch Sitta europea and Treecreeper Certhiafamiliaris showed distinct preferences for different colour backgrounds, reflecting theirchoice of microhabitats and tree species. The data suggest that in the Great Tit the olivemossgreen back colour has evolved as crypsis for foraging close to the base of treetrunks, where most of the moss is found. The bluish-grey back colour of the Nuthatch issuggested to have evolved as crypsis against greyish beech trunks and branches.Similarly the brown back colour of the Treecreeper is suggested to have evolved ascrypsis against pale brown- greyish brown bark surfaces. The possibility that the greyback colour of the Marsh Tit Parus palustris has evolved as crypsis against greyishbranches is discussed. For the Blue Tit Parus caeruleus it is suggested that the greenback colour has evolved as crypsis against leaves during summer; thus no backgroundmatching of the back occurs in winter. For the black back colour of the Longtailed TitAegithalos caudatos no background matching can be suggested. The studydemonstrates that it is possible to quantify background colours for fouraging birds in thewild as seen by a human observer on the ground. It is proposed that these observationsare also representative for a hunting Sparrowhawk Accipiter nisus , even thoughdifferences in observing height and possible differences in spectral visual range maypresent difficulties.
AB - Most drab plumage colours are probably cryptic. Crypsis (camouflage) occurs when thecolour of a significant part of the plumage is similar to the colour of a significant part ofthe background against which the prey bird may be detected by a potential predator. Inthis study we compare back colours of tits and associated species with colourbackgrounds in their habitat during a four-month period in winter. We test thehypothesis that in some of the species back colour is similar to one of the backgroundcolours. In addition to colour backgrounds, microhabitats and tree species were alsorecorded. Great Tit Parus major, Nuthatch Sitta europea and Treecreeper Certhiafamiliaris showed distinct preferences for different colour backgrounds, reflecting theirchoice of microhabitats and tree species. The data suggest that in the Great Tit the olivemossgreen back colour has evolved as crypsis for foraging close to the base of treetrunks, where most of the moss is found. The bluish-grey back colour of the Nuthatch issuggested to have evolved as crypsis against greyish beech trunks and branches.Similarly the brown back colour of the Treecreeper is suggested to have evolved ascrypsis against pale brown- greyish brown bark surfaces. The possibility that the greyback colour of the Marsh Tit Parus palustris has evolved as crypsis against greyishbranches is discussed. For the Blue Tit Parus caeruleus it is suggested that the greenback colour has evolved as crypsis against leaves during summer; thus no backgroundmatching of the back occurs in winter. For the black back colour of the Longtailed TitAegithalos caudatos no background matching can be suggested. The studydemonstrates that it is possible to quantify background colours for fouraging birds in thewild as seen by a human observer on the ground. It is proposed that these observationsare also representative for a hunting Sparrowhawk Accipiter nisus , even thoughdifferences in observing height and possible differences in spectral visual range maypresent difficulties.
M3 - Journal article
SN - 1676-6180
VL - 4
SP - 51
EP - 59
JO - Lundiana
JF - Lundiana
IS - 1
ER -