Great cormorants reveal overlooked secondary dispersal of plants and invertebrates by piscivorous waterbirds

Abstract

21In wetland ecosystems, birds and fish are important dispersal vectors for plants and 22invertebrates, but the consequences of their interactions as vectors are unknown. Darwin 23 suggested that piscivorous birds carry out secondary dispersal of seeds and invertebrates via 24 predation on fish. We tested this hypothesis in the great cormorant (Phalacrocorax carbo L.). 25Cormorants regurgitate pellets daily, which we collected at seven European locations and 26 examined for intact propagules. One-third of pellets contained at least one intact plant seed, 27 with seeds from 16 families covering a broad range of freshwater, marine and terrestrial 28 habitats. Of 21 plant species, only two have an endozoochory dispersal syndrome, compared 29 to five for water and eight for unassisted dispersal syndromes. One-fifth of the pellets 30 contained at least one intact propagule of aquatic invertebrates from seven taxa. Secondary 31 dispersal by piscivorous birds may be vital to maintain connectivity in meta-populations and 32 between river catchments, and in the movement of plants and invertebrates in response to 33 climate change. Secondary dispersal pathways associated with complex food webs must be 34 studied in detail if we are to understand species movements in a changing world. 35 36

Allometric scaling of seed retention time in seed dispersers and its application to estimation of seed dispersal potentials of theropod dinosaurs

“…A set of species of Theropoda have distinctive morphologies adapted for herbivory (Zanno andMakovicky 2011, Pu et al 2013), whereas some of the theropod and ornithischian dinosaurs show direct evidence of fruit or seed consumption (Zhou andZhang 2002, Salgado et al 2017). In addition, carnivorous dinosaurs could have dispersed seeds, either by accidental consumption of seeds or via their consumption of herbivorous animals; this has been confirmed in some extant vertebrates (Nogales et al 2007, van Leeuwen et al 2017. Theropod dinosaurs are direct ancestors of extant birds, and therefore, extrapolations based on trait allometry for extant birds is a commonly used and effective approach for estimating these dinosaurs' traits (Sato et al 2009, Tanaka et al 2015.…”

Impacts of artificial barriers on the connectivity and dispersal of vascular macrophytes in rivers: A critical review

“…Given that ducks and waders can travel upwards of 50 km/hr (Welham, ), there is considerable potential for long‐distance dispersal (Clausen, Nolet, Fox, & Klaassen, ; Van Leeuwen, Velde, Groenendael, & Klaassen, ). There is also evidence that piscivorous birds such as cormorants can act as secondary dispersers of plant seeds (Van Leeuwen, Lovas‐Kiss, Ovegård, & Green, ). Importantly, dispersal by birds is not restricted to river corridors, so inter‐catchment transport is possible, and endozoochorus dispersal of seeds in waterfowl is possible over distances up to 3,600 km (Pollux, ).…”

Crayfish invasion facilitates dispersal of plants and invertebrates by gulls

“…In addition, propagules that may not survive gut passage in one organism may still be dispersed if a predator ingests this organism, and the propagules within, before gut passage has been completed (Hämäläinen et al., ). Studies of secondary dispersal by waterbirds are therefore required to assess its importance in the maintenance of biodiversity and the spread of alien species, and its role in the interactome in aquatic ecosystems (van Leeuwen et al., ; Reynolds, Cumming, Vilà, & Green, ).…”