Nectar Feeding Habits of Loten’s Sunbird Cinnyris lotenius and Purple-rumped Sunbird Leptocoma zeylonica in the Royal Botanical Gardens, Peradeniya, Sri Lanka

Abstract

Sunbirds (Nectariniidae) are small passerines that feed largely on nectar. The aim of thiswork was to observe the relationship of the purple-rumped sunbird Leptocoma zeylonica andLoten’s sunbird Cinnyris lotenius with their host flowers, and to examine their relationshipwith the glucose concentration of nectar, flower count and the length of corolla. The studywas carried out in the Royal Botanical Gardens, Peradeniya, Sri Lanka, between February2013 and September 2013. For each observation, plant species visited for nectar feeding,method of obtaining food, glucose concentration of nectar, length of corolla, and flower countwere recorded. Both species of sunbirds visited Hamelia patens, Sanchezia speciosa,Heliconia rostrata, Megaskepasma erythrochlamys, Strobilanthes flaccidifolius,Graptophyllum pictum and Pachystachys spicata. The male Loten’s sunbird’s occurrence ona given flower is biased by the presence of female (Pearson correlation coefficient: 0.874; PValue:<0.001). The Purple-rumped female’s occurrence is biased by the presence of male(Pearson correlation coefficient: 0.819; P-Value: <0.001). The results also indicated that therewas no significant correlation between the occurrence of the bird and the glucoseconcentration of the flower (Pearson correlation coefficients: -0.045; P-Value: 0.740;[Loten’s male]; -0.094; P-Value: 0.489; [Loten’s female]; -0.061; P-Value: 0.653; [Purplerumpedmale]; 0.001; P-Value: 0.997; [Purple-rumped female]). Similarly, there was nosignificant correlation between the flower count with the occurrence of the bird (Pearsoncorrelation coefficients: 0.160; P-Value: 0.239; [Loten’s male], 0.171; P-Value: 0.208;[Loten’s female]; 0.172; P-Value: 0.595; [Purple rumped male]; 0.211; P-Value: 0.118;[Purple-rumped female]). The Loten’s sunbird has no significant correlation with flowercorolla length (Pearson correlation coefficients: -0.240; P-Value: 0.075; [Loten’s male]; -0.142; P-Value: 0.297; [Loten’s female]). The Purple-rumped sunbird has a significantcorrelation with the flower corolla length. (Pearson correlation coefficient: -0.399; P-Value:0.020; [Purple rumped male]; -0.452; P-Value: <0.001; [Purple-rumped female]). Dependingon the length of corolla, the nectar obtaining method varied as probing or piercing.