Variation in Avian Visits on Two Host Plants of the Mistletoe Tapinanthus sesselifolius Depended on Habitat Type and Presence of Matured Flowers

Abstract

This study investigated avian foraging behaviour on the Mistletoe, Tapinanthus sesselifolius with a view to determine whether avian visits to the stem parasitic plant significantly differ between its two common host plant species in the Amurum Forest Reserve, Nigeria namely; Dichrostachys cinerea and Ochna afzelii. Also the study determined whether habitat type and abundnace of the three flower developmental stages of T. sesselifolius (i.e.closed unripe, closed ripe and open flowers) influenced avian visits to T. sesselifolius. Data was obtained using focal observations; 22 individuals of each of the two plant species hosting the Mistletoe T. sesselifolius were selected through stratified sampling. Focal observations to determine avian visits were conducted over a period of 1-hour per individual plant. Flower developmental stages were sampled through direct counts on three randomly selected branches of the parasitic plant. A significant difference was observed in avian visits to T. sesselifolius on the two study host plants with higher mean visits per hour to T. sesselifolius on D. Cinerea. While T. sesselifolius around the gallery forest habitat received significantly more avian visitors than those located in the savannah scrub and rocky outcrop. Also closed ripe flowers had significant effect on avian visits with avian visits increasing significantly to T. sesselifolius having higher numbers of closed ripe flowers. The complex structure of D. cinerea and the dense vegetation structure of the gallery forest could act as buffer against birds of prey and may have encouraged more visits to T. sesselifolius based on these factors. Also, the tamper proof nature of ripe flowers and its high nectar content as observed in previous studies is speculated as reasons for its significant positive effect on avian visits in the study. These observations may have implications on the reproductive potential of the stem parasitic plant since reduced pollinator visits is known to limit pollen deposition and eventual fruit set in plants.

Keywords: avian visits, Tapinanthus sesselifolius, host plant, habitat type

DOI: 10.7176/JNSR/12-8-01

Publication date: April 30^th 2021