Spatial and seasonal movement patterns of fynbos nectar-feeding bird pollinators from ring repeat records

Abstract

How species move through fragmented landscapes is critical to the resilience of ecological interactions, yet movement data are scarce for most taxa. Habitat loss and fragmentation affect the movement of nectar-feeding bird species, impacting plant-pollinator interactions. Here we use 75 years (1950–2025) of bird ringing data obtained from the South African Bird Ringing Scheme (SAFRING). Our main aims were to (i) determine the spatial movement patterns of nectar-feeding birds with varying degrees of habitat specialisation, and (ii) elucidate nectar-feeding bird movement between breeding and non-breeding seasons. The study focused on the four most abundant nectarivorous bird species in a region of the southwestern Cape, South Africa, marked by Velddrif and Witsand as the northern- and eastern-most points, respectively. These are the Southern Double-collared Sunbirds Cinnyris chalybeus (SDcS), Orange-breasted Sunbirds (ObS) Anthobaphes violacea, Malachite Sunbirds (MS) Nectarinia famosa and Cape Sugarbirds (CSb) Promerops cafer. All movements were mapped, and distances travelled during the breeding and non-breeding seasons were compared. Fire and ringing records were then assessed to determine movement in response to fire. Recaptures, resightings and recoveries were combined as ‘repeats’. No clear movement pattern was discernible, owing to an insufficient number of repeats. Repeat rates ranged from 2.8% for MS to 10.1% for CSb. The habitat-generalist MS and SDcS travelled further than the fynbos-dependent CSb and ObS. If only considering the distance between a single breeding and non-breeding season, MS travelled the farthest (28.9 km) and ObS the least (1.8 km). The concentration of ringing effort within the urban zone of influence means movement patterns between natural and transformed landscapes remain largely unknown. This highlights the need for targeted sampling across urban gradients combined with modern technology, such as GPS tracking, to fully understand pollinator movement in fragmented landscapes.