Physiological tipping points in the relationship between foraging success and lifetime fitness of a long‐lived mammal

Abstract

Although anthropogenic change is often gradual, the impacts on animal populations may be precipitous if physiological processes create tipping points between energy gain, reproduction or survival. We use 25 years of behavioural, diet and demographic data from elephant seals to characterise their relationships with lifetime fitness. Survival and reproduction increased with mass gain during long foraging trips preceding the pupping seasons, and there was a threshold where individuals that gained an additional 4.8% of their body mass (26 kg, from 206 to 232 kg) increased lifetime reproductive success three‐fold (from 1.8 to 4.9 pups). This was due to a two‐fold increase in pupping probability (30% to 76%) and a 7% increase in reproductive lifespan (6.0 to 6.4 years). The sharp threshold between mass gain and reproduction may explain reproductive failure observed in many species and demonstrates how small, gradual reductions in prey from anthropogenic disturbance could have profound implications for animal populations.

Individual variation in life-history timing: synchronous presence, asynchronous events and phenological compensation in a wild mammal

“…The same pattern has been found in seals [ 9 ] and birds [ 29 ]. For reproductively successful elephant seals, delaying moult could mean a shorter foraging trip afterwards, during the crucial period when females are diving nearly continuously and consuming thousands of fish daily [ 31 , 50 ] to support gestation and prepare for the upcoming lactation period [ 51 ]. The relative synchrony of haul-out timing but asynchrony of moult timing could mean that predator aggregation potential is still high, as other studies have found [e.g.…”

Indication of feeding ground inside the Manta Ray's cleaning station by investigation of the zooplankton community composition in Raja Ampat Islands, Indonesia

“…Feeding activity can determine the animal's distribution (Fortune et al 2020), reproductive success (Beltran et al 2023), food availability (Billard et al 2020), as well as evolutionary patterns through niche specialization (Dehnhard et al 2020). Therefore, understanding the feeding activity, particularly that of a threatened organism such as a manta ray, may promote its conservation management effectively.…”