Lifelong foraging and individual specialisation are influenced by temporal changes of resource availability

Abstract

Resource availability largely determines the distribution and behaviour of organisms. In plant–pollinator communities, availability of floral resources may change so rapidly that pollinator individuals can benefit from switching between multiple resources, i.e. different flowering plant species. Insect pollinator individuals of a given generation often occur in different time windows during the reproductive season. This temporal variation in individual occurrences, together with the rapidly changing resource availability, may lead individuals of the same population to encounter and use different resources, resulting in an apparent individual specialisation. We hypothesized, that 1) individual pollinators change their resource use (flower visitation) during their lifetime according to the changing availability of floral resources, and that 2) temporal variation in individual occurrences of pollinators and in resource availability will partly explain individual specialisation. To test these hypotheses, we observed flower visitations of individually marked clouded Apollo butterflies Parnassius mnemosyne during one reproductive season. We found temporal changes in lifetime individual resource use that followed the changes in resource availability, indicating that butterflies can adjust foraging to varying resource availability. Individuals differed considerably in their resource use. This variation was partly explained by temporal variation in both floral resource availability and temporal occurrence of individual butterflies. We suggest the butterfly as a sequential specialist, i.e. short‐term specialist and long‐term generalist. This foraging plasticity can be essential for short‐living insect pollinators in rapidly changing environments. Although flowering dynamics do not fully explain the variability in foraging, our results highlight the importance of temporal dimension in resource use studies. Ultimately, the relative pace of environmental change compared to individual lifespan may be a key factor in resource use plasticity.

Year-round temporal stability of a tropical, urban plant-pollinator network

“…Analyzing complete pollination networks provides a more accurate understanding of the community, since both plants and pollinators typically interact with more than one partner [5][6][7]. Moreover, studying changes in pollination networks over time can (1) improve our understanding of pollination services, as most angiosperm species rely on animal pollinators [8,9]; (2) provide clarity on whether species are specialists, generalists, or sequential specialists [10,11]; (3) facilitate predictions of how plants, pollinators, and their interactions will respond to climate change [12]; and (4) provide critical information that can help with conservation efforts of both pollinators, which are undergoing population declines worldwide, and the plants that depend on them for reproduction [13,14].…”

Opportunistic predation of birds by breeding Herring Gulls (Larus argentatus)

“…Specialist predators have a narrow dietary niche, exploiting a small fraction of available resources, often more efficiently than generalists that utilize a wider range of prey [1]. There has been growing interest in the causes and consequences of individual specialization, especially in diet studies [2][3][4][5][6]. Individual dietary specialization has been widely reported for seabirds, most commonly among Charadriiform species, of which large gulls Larus spp.…”

Enhancing dietary specialization metrics in observational studies of wild animal populations

“…These benefits make it worth asking whether we can quantify or even correct for uncertainty in dietary estimates derived from small sample sizes. Currently, some studies exclude individuals falling below an arbitrary sample size cutoff (e.g., 6 in De León et al 2012, 8 in Szigeti et al 2018), but this can significantly reduce statistical power, particularly in field studies where sample sizes may already be limited (Garamszegi 2016). Existing statistical tools may enable us to retain more individuals.…”

“…This effect can be compounded by phenological changes. For example, Szigeti et al (2018) found that pairs of Apollo butterflies ( Parnassius mnemosyne ) had more similar diets the closer in time they were observed to one another, suggesting that phenology at the time of observation can significantly influence diet scores. Yet, studies of dietary variation rarely include detailed habitat or phenology assessments.…”