Opportunistic nectar‐feeding birds are effective pollinators of bird‐flowers from Canary Islands: experimental evidence from Isoplexis canariensis (Scrophulariaceae)

Abstract

Insular floras, characterized by simple pollination networks, sometimes include novel mutualistic agents such as nonspecialist nectarivores. In this study we confirmed the effective pollination of Isoplexis canariensis by opportunistic nectar-feeding birds in Tenerife, Canary Islands, Spain. This plant is among the ornithophilous species of the Canarian flora that lack past and present specialist nectarivorous birds. Experimental hand pollinations revealed self-compatibility, but cross-pollinated flowers produced a greater percentage of viable seeds than self-pollinated ones. Flowers were visited by five species of birds (Phylloscopus canariensis, Parus caeruleus, Sylvia melanocephala, Serinus canarius, and Fringilla coelebs) and by the endemic lizard (Gallotia galloti, Lacertidae). Insect pollination was absent, and the few insect visitors acted as nectar thieves or secondary nectar robbers. Birds represented 93.1% of total visits, with the Canarian Chiffchaff, Ph. canariensis, being the most frequent visitor. Flowers visited by birds set more, larger, and heavier fruit than flowers from which birds were excluded. Bird visitation also enhanced seed viability. These results demonstrate the active role of these opportunistic birds as effective pollinators of this Canarian bird-flower species. Further, the results reveal the need to consider the effect of these birds on the evolution of ornithophilous floral traits in absence of specialist nectarivores.

Pollinator shifts drive petal epidermal evolution on the Macaronesian Islands bird-flowered species

“…This modification might be associated with changes in feeding behaviours between insects and passerine birds. These birds do not land in the flowers (as most insects do), but rather they forage from the ground, a nearby branch or by hovering [12,18,19]. Thus, the main mechanical interaction occurs when the bird collects nectar from the flower.…”

Conservation of oceanic island floras: Present and future global challenges

“…Although data are accumulating on aspects of the reproductive biology of various Azorean (Pereira, 2008) and Canarian endemics (e.g. Calero and Santos-Guerra, 1993;Anderson et al, 2006;Dupont and Olesen, 2006;Crawford et al, 2008;Rodríguez-Rodríguez and Valido, 2008), a broad knowledge of this aspect of the flora in all Macaronesian archipelagos is lacking, which impedes understanding of the biological implications of most population genetic studies (e.g. Caujapé -Castells et al, 2008a, b).…”

Yuhina nigrimenta Blyth (Zosteropidae) as a bird pollinator ofBrandisia hancei Hook.f. (Scrophulariaceae) during winter

“…The B. hancei Hook.f. flower is large in size and unscented; it also presents red long-tubular corolla, diurnal anthesis, and anthers covered with dense hairs; these characteristics are considered those of avian pollination in other species (Endress and Steiner-Gafner, 1996;Sánchez-Lafuente, 2005;Rodríguez-Rodríguez and Valido, 2008). According to our observations, the only visitor of B. hancei Hook.f.…”