Multi-Species Feeding Association Dynamics Driven by a Large Generalist Predator

Abstract

Multi-species feeding associations (MSFAs) are temporary communities of animals exploiting the same or co-occurrent resources. Their dynamics are species dependent, often creating competitive interactions, but they can also increase foraging efficiency and ultimately individual fitness. The foraging behaviors of some species can enhance prey capture by others, with different roles depending on the species present. Here, we use the Hauraki Gulf, New Zealand, as a model system to quantitatively characterize the principal types of MSFAs between 2011 and 2020. We determine the foraging associations of a large generalist predator, the Bryde’s whale, and how shifts in its prey preference change the dynamics between seabird competitors. Hierarchical clustering from influential predator groups identified three types of MSFAs. Two of mainly fish-feeding predators, one including and one lacking Bryde’s whales, and one involving (although not limited to) plankton-feeders associated with Bryde’s whales. Cluster frequencies featured significant temporal trends, whereas MSFA diversity and whale association rate showed no significant changes. Bryde’s whales’ increasing reliance on zooplankton highlights their foraging plasticity, with changes in cluster frequencies and resource competition related to this shift from fish to zooplankton. The role of Bryde’s whales varies from joiners and terminators in fish-feeding aggregations to initiators with plankton-feeding seabird associations, thereby changing the MSFA dynamics. MSFAs tend toward a diversity equilibrium, i.e., a maximum number of species involved before competitive effects exceed the benefits of interaction. Functional MSFAs where heterospecific interactions are important to foraging success can be affected by changing composition. Future work should focus on the behavioral interactions between key predators, prey availability and their effect on MSFAs.

Fine‐scale spatial and temporal distribution patterns of large marine predators in a biodiversity hotspot

“…Static variables were important in all habitat models and defined the general ecological niches of various species, and predictions were generally consistent with current knowledge (Dwyer et al, 2016, 2020; Francis, 2016; Gostischa et al, 2021). For example, bronze whaler sharks and bottlenose dolphins are classified as coastal species, reflected by their predicted preference for shallow waters close to shore.…”

“…The Hauraki Gulf/ Tīkapa Moana/ Te Moananui‐ā‐Toi, Aotearoa New Zealand (henceforth the Gulf), is a highly productive marine environment that supports a diverse community of resident and migratory large marine predators (Gostischa et al, 2021; Whitehead et al, 2019). It is a seasonally stratified wind‐driven coastal upwelling marine ecosystem that sits on a wide shelf (~60 km; Stevens et al, 2019).…”

Feeding tactics of resident Bryde's whales in New Zealand

“…In contrast, fish-feeding events targeted scattered prey aggregations, which disappeared after a few minutes supporting only a limited number of lunges. Such prey aggregations were simultaneously targeted by multiple predators, including common dolphins, Australasian gannets, and other seabirds which benefit from the aggregation response of prey to predation, even though they compete for this ephemeral resource (Gostischa et al, 2021). As a result, the movement paths of Bryde's whales when foraging on fish showed little tortuosity.…”

“…The lateralized rolls were also detected in the tag data captured prey independently of other predators. In contrast, surface lunges on fish always occurred in multispecies aggregations with common dolphins (Delphinus delphis), and seabirds, most notably Australasian gannets present (Gostischa et al, 2021). Feeding on both zooplankton and fish occurred in all seasons.…”

Following the feeder: A global synthesis of disturbance‐based foraging associations of birds

“…Interspecific feeding associations between seabirds and marine mammals have been documented extensively (e.g. Brager, 1998; Gostischa et al., 2021; Penry et al., 2011; Ridoux, 1987; Stockin et al., 2009) and typically involve multiple bird species gathering in the presence of schools of fish. Dolphins and other cetaceans are widely recognized as both charismatic megafauna and ecological health indicator species, but are not typically viewed as the cornerstone of their ecosystems (Giralt Paradell et al., 2020; Parsons et al., 2015).…”