Prey Density Research Articles

Functional response of Neoseiulus californicus (Acari: Phytoseiidae) to Tetranychus urticae (Acari: Tetranychidae) at different temperatures.

Environmental factors like temperature have a great impact on the predation potential of biological control agents. In the present study, the functional response of the predatory mite Neoseiulus californicus (Acari: Phytoseiidae) to the pest mite Tetranychus urticae (Acari: Tetranychidae) at moderate to high temperatures under laboratory conditions was determined. The study aimed to understand the prey-predator interaction under different temperatures and prey densities. Five constant temperatures (24 °C, 27 °C, 30 °C, 33 °C, and 36 °C), and thirteen prey densities (4, 5, 8, 10, 12, 15, 16, 20, 24, 25, 30, 32, and 40) of each stage (adult, nymph, larvae, and egg stage) were employed in the experiment. Observations were made 24 h after the start of each experiment. Results revealed that the predatory mites showed type II functional response to adult females of T. urticae, whereas type I to other stages (nymphs, larvae, and eggs) of T. urticae. The predation capability of adult predatory mites on T. urticae was significant at 24-36 °C. The instantaneous attack rate (a) of N. californicus increased and the handling time (Th) decreased with an increase in temperature. The maximum attack rate was recorded at 36 °C (1.28) for the egg stage. The longest handling time was (0.78) for the larval stage of T. urticae at 30 °C. Daily consumption increased with increasing prey density. Maximum daily consumption was observed at 33 °C (30.00) at the prey density of 40. Searching efficiency decreased with the increase in prey density but was found to increase with the rise in temperature. N. californicus was found to be voracious on the larval and egg stages. Conclusively, the incorporation of N. californicus at earlier stages (larvae and eggs) of T. urticae would be beneficial under warm conditions because managing a pest at its initial stage will save the crop from major losses. The results presented in this study at various temperatures will be helpful in different areas with different temperature extremes. The results of the functional response can also be applied to mass rearing, quality testing, and integrated pest management programmes.

The impact of conspecific presence on diet-induced developmental responses in a predatory mite

Diet and social experience during development can have profound influences on the fitness of individuals and subsequently affect population dynamics. Understanding the factors driving population size is fundamental to ecological studies and pest management. In this study, we investigated the interplay between diet-induced plasticity, cannibalism, social interactions, and life history traits in Phytoseiulus persimilis Athias-Henriot, a natural predator of the two-spotted spider mite, Tetranychus urticae Koch. This research explored how varying prey densities and the presence of a non-feeding conspecific during P. persimilis’ immature development impacts survival, cannibalism, prey consumption, developmental time, and size at maturity. Results show that survival rates are influenced by prey availability, with an increase in cannibalism observed under low prey density conditions. The presence of non-feeding conspecifics had a significant impact on P. persimilis, leading to increased prey consumption, accelerated immature development, and reduced size at maturity. These findings provide insights into the complex dynamics of predator-prey interactions and offer valuable implications for pest management strategies involving P. persimilis. The influence of diet and social interaction on additional life history traits, such as lifespan and fecundity, should be examined in future studies.

DYNAMIC STUDY OF A RATIO-DEPENDENT PREDATOR–PREY MODEL WITH STRONG ALLEE EFFECT AND NONLINEAR HARVESTING

The harvesting of species occurs in terrestrial and aquatic habitats across the world. It not only causes alteration in the population structure of the species subjected to harvesting but also of the species in interaction with the harvested species. The present work investigates the effect of nonlinear prey harvesting on the dynamics of a ratio-dependent predator–prey system with a strong Allee effect in prey population. It is found that the system exhibits a rich spectrum of dynamics including saddle-node bifurcation, Hopf bifurcation and homoclinic bifurcation with respect to the parameters that shape the nonlinear harvesting rate, namely, the maximum harvesting rate and a half-saturation constant that represents the prey density at which half of the maximum harvesting rate is reached. It is found that the basin of attraction of the stable coexistence state shrinks as the harvesting rate increases and if the harvesting rate is above a threshold value at which saddle-node bifurcation occurs, the stable coexistence of predator and prey populations is not possible for any initial start. It is also found that the harvesting policies in which the harvesting rate increases less rapidly at low prey population size are more favorable for the stable coexistence of species. The presence of Allee effect in the prey population is found to increase the chances of extinction of both species by reducing the threshold value of the harvesting rate at which the unconditional extinction occurs. Numerical simulations are carried out to support the analytical findings.

Predicting carrying capacity of a large carnivore from prey densities: a new approach.

Large carnivores play a crucial role in maintaining the balance of the ecosystem. Successful conservation initiatives have often led to a huge increase in predators which has often led to negative interactions with humans. Without the knowledge of the carrying capacity of the top predator, such decisions become challenging. Here, we have derived a new equation to estimate the carrying capacity of tigers based on the individual prey species density. We used tiger densities and respective prey densities of different protected areas. Relative prey abundance was used instead of absolute prey density as this could be a better surrogate of the prey preference. We used a regression approach to derive the species-wise equation. We have also scaled these coefficients accordingly to control the variation in the standard error (heteroscedasticity) of the tiger density. Furthermore, we have extended this regression equation for different species to different weight classes for more generalized application of the method. The new equations performed considerably better compared to the earlier existing carrying capacity equations. Incorporating the species-wise approach in the equation also reflected the preference of the prey species for the tiger. This is the first carrying capacity equation where the individual prey densities are used to estimate the carnivore population density. The coefficient estimates of the model with the comparison with prey-predator power laws also reflect the differential effect of tigers on different prey species. The carrying capacity estimates will aid in a better understanding of the predator-prey interaction and will advance better management of the top predator.

Dynamics of Zooplankton Consumption by the Three-speed Stickleleback <i>Gasterosteus aculeatus</i> (Linnaeus, 1758) at Different Densities of the Predator

An experiment was set up to estimate the rate of zooplankton consumption by the three-spined stickleback Gasterosteus aculeatus (Linnaeus, 1758) at different predator densities. A differential equation describes the dynamics of zooplankton abundance depending on duration of predator feeding. The derived function accurately characterizes the rate of zooplankton consumption by stickleback in the experiment, demonstrating a good agreement between the theoretical prerequisites and the experimental results. The relationship between changing a number of prey during predation, its mortality and consumption rate was revealed. The hypothesis of consumption rate proportional to the number of predators was tested. A comparative analysis of ingestion rate as a function of time and a function of prey density was performed.

Numerical response of predator to prey: Dynamic interactions and population cycles in Eurasian lynx and roe deer

AbstractThe dynamic interactions between predators and their prey have two fundamental processes: numerical and functional responses. Numerical response is defined as predator growth rate as a function of prey density or both prey and predator densities [dP/dt = f(N, P)]. Functional response is defined as the kill rate by an individual predator being a function of prey density or prey and predator densities combined. Although there are relatively many studies on the functional response in mammalian predators, the numerical response remains poorly documented. We studied the numerical response of Eurasian lynx (Lynx lynx) to various densities of its primary prey species, roe deer (Capreolus capreolus), and to itself (lynx). We exploited an unusual natural situation, spanning three decades where lynx, after a period of absence in central and southern Sweden, during which roe deer populations had grown to high densities, subsequently recolonized region after region, from north to south. We divided the study area into seven regions, with increasing productivity from north to south. We found strong effects of both roe deer density and lynx density on lynx numerical response. Thus, both resources and intraspecific competition for these resources are important to understanding the lynx population dynamic. We built a series of deterministic lynx–roe deer models, and applied them to the seven regions. We found a very good fit between these Lotka–Volterra type models and the data. The deterministic models produced almost cyclic dynamics or dampened cycles in five of the seven regions. Thus, we documented population cycles in this large predator–large herbivore system, which is rarely done. The amplitudes in the dampened cycles decreased toward the south. Thus, the dynamics between lynx and roe deer became more stable with increasing carrying capacity for roe deer, which is related to higher productivity in the environment. This increased stability could be explained by variation in predation risk, where human presence can act as prey refugia, and by a more diverse prey guild that will weaken the direct interaction between lynx and roe deer.

Large sensory volumes enable Southern elephant seals to exploit sparse deep-sea prey

The ability of echolocating toothed whales to detect and classify prey at long ranges enables efficient searching and stalking of sparse prey in these time-limited dives. However, nonecholocating deep-diving seals such as elephant seals appear to have much less sensory advantage over their prey. Both elephant seals and their prey rely on visual and hydrodynamic cues that may be detectable only at short ranges in the deep ocean, leading us to hypothesize that elephant seals must adopt a less efficient reactive mode of hunting that requires high prey densities. To test that hypothesis, we deployed high-resolution sonar and movement tags on 25 females to record simultaneous predator and prey behavior during foraging interactions. We demonstrate that elephant seals have a sensory advantage over their prey that allows them to potentially detect prey 5 to 10 s before striking. The corresponding prey detection ranges of 7 to 17 m enable stealthy approaches and prey-specific capture tactics. In comparison, prey react at a median range of 0.7 m, close to the neck extension range of striking elephant seals. Estimated search swathes of 150 to 900 m2 explain how elephant seals can locate up to 2,000 prey while swimming more than 100 km per day. This efficient search capability allows elephant seals to subsist on prey densities that are consonant with the deep scattering layer resources estimated by hydroacoustic surveys but which are two orders of magnitude lower than the prey densities needed by a reactive hunter.

Perceptions of farmers towards carnivores in an Ethiopian protected area

AbstractWe explored farmers' perceptions of the causes and consequences of human‐carnivore conflict in Maze National Park, Ethiopia. We selected 225 household heads randomly from five villages for interview using survey questionnaires. We identified the five villages randomly from the 16 that border the park. The majority (75.1%) of the respondents had a negative perception towards the park and the carnivores due to livestock depredation. Overall, 1142 livestock depredation were reported over 3 years (2017–2019). Cattle, sheep and goats were reportedly the most depredated animals. The numbers of livestock depredated significantly varied among villages and predators. Farmers perceived lions as the major livestock depredator followed by leopards and spotted hyaenas and they perceived that proximity, poor livestock husbandry and low natural prey density were the main causes of livestock depredation. The distance of the household holdings to the park was correlated negatively with the depredation level. Farmers use guarding, cut‐and‐carry systems and dogs to reduce carnivores' predation. Allocating enough spatial differences between the park and the villages and altering the timing and frequency with which livestock grazing overlaps with the diurnal activities of carnivores may lead to a win–win outcome promoting coexistence.

Predator home range size mediates indirect interactions between prey species in an arctic vertebrate community.

Indirect interactions are widespread among prey species that share a common predator, but the underlying mechanisms driving these interactions are often unclear, and our ability to predict their outcome is limited. Changes in behavioural traits that impact predator space use could be a key proximal mechanism mediating indirect interactions, but there is little empirical evidence of the causes and consequences of such behavioural-numerical response in multispecies systems. Here, we investigate the complex ecological relationships between seven prey species sharing a common predator. We used a path analysis approach on a comprehensive 9-year data set simultaneously tracking predator space use, prey densities and prey mortality rate on key species of a simplified Arctic food web. We show that high availability of a clumped and spatially predictable prey (goose eggs) leads to a twofold reduction in predator (arctic fox) home range size, which increases local predator density and strongly decreases nest survival of an incidental prey (American golden plover). On the contrary, a scattered cyclic prey with potentially lower spatial predictability (lemming) had a weaker effect on fox space use and an overall positive impact on the survival of incidental prey. These contrasting effects underline the importance of studying behavioural responses of predators in multiprey systems and to explicitly integrate behavioural-numerical responses in multispecies predator-prey models.

A generalist predator–prey system with the effects of fear and refuge in deterministic and stochastic environments

In the present study, we investigate the dynamics of a generalist predator–prey system by considering that the fear of predators suppresses the birth rate and enhances the intraspecies competition of the prey species. Also, we assume that a constant proportion of the prey population is taking refuge, which results in a reduction in the predation pressure. We consider Cosner functional response to describe the interactions between prey and predator species. We rigorously analyze the proposed model analytically as well as numerically. We see that the system exhibits multi-stable configurations under identical ecological conditions by allowing different bifurcation scenarios, including saddle–node, Hopf and transcritical bifurcations with varying degrees of fear, on the prey’s reproduction and intraspecies competition, induced by the predator species. The emergence of multistability scenarios in the system is also stimulated by the birth rate of prey species and the growth in predator species due to the additional food sources. We modify our proposed model to its stochastic counterpart by considering the impact of environmental white noises on the natural death rates of both prey and predator species. The simulation results for the stochastic system demonstrate that the fluctuations in the densities of prey and predator populations due to stochastic perturbations are highly sensitive to the intensities of the environmental noises. Additionally, we find that the stochastic system showcases noise-induced transitions whenever the deterministic system exhibits bistability.

Distribution Pattern and Activities of Felidae and Prey in Bukit Rimbang Bukit Baling Wildlife Reserve, Riau

The interaction between predators and prey has resulted in population dynamics and played a crucial role in maintaining species' populations within ecosystems. This research aimed to identify distribution and activity patterns to understand prey-predator interactions and the effect of environment and prey density on Felidae presence at Bukit Rimbang Bukit Baling Wildlife Reserve (BRBB WR), as an essential area for maintaining large mammal habitats in Sumatra. The camera traps were systematically placed in the Northeastern part of BRBB WR to collect presence data. The prey-predator interaction analysis used kernel density in RStudio. The effect of environment and prey density on Felidae presence was analyzed using a generalized linear model (GLM). The results indicated that Felidae and prey exhibited a dispersed distribution pattern, showing high activity at night and day, respectively. The Sumatran tiger, clouded leopard, leopard cat, and mouse deer had the highest overlap time (>0.50). However, the environmental and prey density had statistically non-significant effects on the presence of Felidae. Human activities in the area potentially disrupted wildlife community dynamics, although this aspect was beyond the scope of this research. This research suggested further investigation of the effects of human activities on wildlife communities in BRBB WR.

Sustained ecological impacts of invasive crayfish following claw injury

ABSTRACT Human activities have significantly accelerated the translocation of species outside their native range with severe consequences for global biodiversity. Freshwater crayfish are a particularly successful group of invasive species, as exemplified by the increasingly widespread marbled crayfish Procambarus virginalis Lyko, 2017. A significant portion of crayfish populations has regenerating or missing claws. At the same time, claws play important roles in crayfish feeding and intraspecific interactions, altering their ability to invade new areas and impact native communities. Here, using functional response analyses, we combined laboratory experiments and modeling to investigate whether the number of claws on marbled crayfish modulates its ecological impact (focusing on predation rate) as well as its intraspecific interactions via population dynamic modeling. We found that the number of claws did not affect the marbled crayfish’s functional response type (hyperbolic type II), attack rates, or handling times when preying on chironomid larvae. Rates of partial prey consumption were overall low (<2%), and claw number had a significant effect on the partial consumption rate of prey, which tended to increase with the number of claws and prey density. The presence of multiple intraspecific predators influenced marbled crayfish non-trophic behavior, with antagonistic effects prevalent between crayfish pairs regardless of claw status. Moreover, the impact of multiple predators was prey density-dependent, with the highest levels of antagonism shown at the lowest prey density across crayfish groups. Our findings indicate that the ecological influence of invasive crayfish remains unchanged by the number of claws, highlighting the escalating, context-independent threat these species pose to freshwater ecosystems.

Community knowledge on factors behind extirpation of lion Panthera leo in Comoé National Park, Côte d'Ivoire (West Africa)

AbstractA rise in human disturbance in Comoé National Park (CNP) has led to lion (Panthera leo) extirpation. After the crisis, there have been numerous efforts to restore this ecosystem and CNP's management authority is considering reintroducing lions. This ideally requires an understanding of the earlier process of lion extirpation. We assessed the causes of lion extirpation through semi‐structured questionnaires to 307 volunteer participants in surrounding 23 villages. Respondents reported that lions were extirpated two decades ago (19.75 years ± 8.15). Bouna was the sector that lions seem to have disappeared first (mean = 23.61 years ± 9.14) and recently on Nassian and Téhini sectors (mean = 18.43 years ± 8.17 and 18.74 years ± 6.74 respectively). People identified civil war from 2002 as the main facilitator of lion extirpation (85%; n = 261), which led to the abandonment of CNP, and opened the way for all forms of anthropogenic pressures including illegal hunting and prey depletion (70%; n = 216), illegal gold mining (74%; n = 227), direct lion killing due to transhumance and human‐wildlife conflict (15%; n = 45), and wildfires (23%; n = 72). Historically, prey density curves show a progressive decrease with a drastic drop during the civil war period before a post‐crisis recovery from 2016 to 2022. We recommend intensifying CNP monitoring and local measures to limit anthropogenic disturbances and improve indigenous communities' involvement to ensure the success of potential lion reintroduction.

Environmental factors and prey availability determine wintering habitat use by shorebirds along the west coast of India.

The spatial and temporal factors governing shorebird habitat use are crucial for managing coastal habitats and halting the decline of shorebird populations in the Central Asian Flyway. Therefore, we investigated how environmental variables and prey availability influenced shorebird distribution and abundance across habitats and seasons along the west coast of India between January 2015 and December 2016. Systematic sampling design was followed to collect data on shorebirds, sediment and hydrological properties (organic matter and physico-chemical properties), and prey availability across habitats over different seasons. Prey density and environmental variables such as salinity, organic matter, and sediment moisture content differed significantly across habitats and seasons. Prey density was influenced by salinity, with higher densities in mudflats (>1000 individuals per m2) during the winter season. Prey density decreased considerably in all coastal habitats during the departure (748.45 ± 320.93) and breeding seasons (537.55 ± 342.29). The fluctuations in prey density and salinity levels had a strong influence on distribution and abundance of shorebirds. These findings highlight the importance of mudflats as a foraging ground during the winter and freshwater inflow in maintaining salinity in estuarine habitats. Therefore, any alteration of river flow (e.g., construction of dams and check dams) or mudflats (e.g., mangrove plantations) would have a serious impact on the availability of prey organisms and the population of shorebirds that depend on them along the Central Asian Flyway.

The relative importance of social information use for population abundance in group-living and non-grouping prey

Predator–prey relationships are fundamental components of ecosystem functioning, within which the spatial consequences of prey social organization can alter predation rates. Group-living (GL) species are known to exploit inadvertent social information (ISI) that facilitates population persistence under predation risk. Still, the extent to which non-grouping (NG) prey can benefit from similar processes is unknown. Here we built an individual-based model to explore and compare the population-level consequences of ISI use in GL and NG prey. We differentiated between GL and NG prey only by the presence or absence of social attraction toward conspecifics that drives individual movement patterns. We found that the extent of the benefits of socially acquired predator information in NG highly depends on the prey’s ability to detect nearby predators, prey density and the occurrence of false alarms. Conversely, even moderate probabilities of ISI use and predator detection can lead to maximal population-level benefits in GL prey. This theoretical work provides additional insights into the conditions under which ISI use can facilitate population persistence irrespective of prey social organisation.

Temperature and prey density drive growth and otolith formation of the world's most valuable fish stock

Peruvian anchovy (Engraulis ringens) represents the largest single-species fishery worldwide. Knowledge on how temperature and prey availability influences growth and age estimation during marine fish early life stages is critical for predicting bottom-up processes impacting stock productivity under changing environmental conditions. We reared Peruvian anchovy larvae at two temperatures (14.5 and 18.5 °C) and prey concentrations [high (HF), and low (LF)] from 6 to 30 days post-hatch (dph) to measure growth rate and examine daily deposition of otolith increments. Peruvian anchovy larvae grew faster at 18.5 °C compared to 14.5 °C. Larvae reared at low prey concentration (18.5-LF) and low temperature (14.5-HF) grew 61 and 35% slower, respectively, than those at high prey and warm temperature (18.5-HF). Age and growth rates of larvae were well depicted in the otolith microstructure of well-fed larvae at 18.5 °C. However, larvae reared at 18.5-LF or 14.5-HF, had only 55 and 49% of the expected number of daily otolith increments. Our results suggest caution when attempting to explore how ocean processes regulate small pelagic stocks, the productivity of which are largely driven by changes in the survival and growth of young larvae.

Effect of Short-Term High-Temperature Stimuli on the Functional Response of Trichopria drosophilae (Matsumura).

Researchers have previously investigated the role of Trichopria drosophilae as a pupal parasitoid in the biological control of Drosophila suzukii in China. Here, we investigated the ability of T. drosophilae to parasitize D. suzukii pupae at different temperatures. To do this, we evaluated the functional response of T. drosophilae to D. suzukii pupae at different temperatures and investigated the specific effects of density on parasitism. The results show that the parasitic functional response of T. drosophilae under different high-temperature stimuli is Holling type II. After processing at 29 °C, the instantaneous search rate was 1.1611; the theoretical maximum parasitic value was 20.88 at 31 °C. The parasitic efficiency decreased with increasing stimulation temperature, as the host pupa density increased from 5 to 25, and the strongest search effect occurred at 0.87 at 27 °C. The searching effect of T. drosophilae at each temperature fell gradually with an increase in prey density from 5 to 25. At 31 °C, the theoretical parasitic maximum of T. drosophilae reached a maximum of 20.88 pupae. At this temperature, when a pair of T. drosophilae was placed in a pupa density of 50, its actual total number of parasites was 18.60.

Density-dependent predatory impacts of an invasive beetle across a subantarctic archipelago

Biological invasions represent a major threat to biodiversity, especially in cold insular environments characterized by high levels of endemism and low species diversity which are heavily impacted by global warming. Terrestrial invertebrates are very responsive to environmental changes, and native terrestrial invertebrates from cold islands tend to be naive to novel predators. Therefore, understanding the relationships between predators and prey in the context of global changes is essential for the management of these areas, particularly in the case of non-native predators. Merizodus soledadinus (Guérin-Méneville, 1830) is an invasive non-native insect species present on two subantarctic archipelagos, where it has extensive distribution and increasing impacts. While the biology of M. soledadinus has recently received attention, its trophic interactions have been less examined. We investigated how characteristics of M. soledadinus, its density, as well as prey density influence its predation rate on the Kerguelen Islands where the temporal evolution of its geographic distribution is precisely known. Our results show that M. soledadinus can have high ecological impacts on insect communities when present in high densities regardless of its residence time, consistent with the observed decline of the native fauna of the Kerguelen Islands in other studies. Special attention should be paid to limiting factors enhancing its dispersal and improving biosecurity for invasive insect species.

Predatory Performance of &lt;i&gt;Microvelia douglasi&lt;/i&gt; Scott (Hemiptera: Veliidae) with Reference to Diel Periodicity

The present work centers on the predatory performance of Microvelia douglasi adults with reference to diel periodicity. This experiment attempts to determine on whether the foraging efficiency was more at diurnal or nocturnal period, and was there an endogenous rhythm available within them to activate foraging response. The study was conducted in the laboratory for 24 hr with an interval of every three hr. The experiment was divided into Phase I (LD 12:12) and Phase II (DL 12:12). The predatory efficiency of M. douglasi adults was investigated on the first and second instars of Anopheles stephensi at prey densities of 25 and 50, and the experiment was conducted separately for male, female, and for both male and female, in 500 mℓ and 1000 mℓ containers. The bugs showed predatory activity both in diurnal and nocturnal periods. In LD cycle, maximum predatory activity was at 15:00 hr by the female bugs, and a total of 350.0 An. stephensi larvae were predated with 144.6 and 205.4 prey predated at 25 and 50 prey density, respectively. The male bugs predated 110.4 prey, and their response was less than that of females, which showed the highest rate of predation as they predated 129.4 prey. The prey predated when both male and female were put together was 110.2. In DL cycle, maximum predatory activity occurred at 24:00 hr again by the female bugs, and a maximum of 327.8 larval instars were predated with 153.4 and 174.4 prey predated at 25 and 50 prey density, respectively. Female bugs predated (121.2) more prey than male (99.4). However, the prey predated when both male and female were put together was 107.2, which was higher than prey predated by male. In LD cycle, the bugs predated more first instar (186.0) than the second instar (164.0), and in DL cycle, there was not much difference as 163.2 and 164.6 first and second instar, respectively were predated. Overall, the bugs showed more predatory activity during light than in dark, though natural light was changed to dark and dark to light. Predator’s sex, prey size, and different photoperiods testified the predatory performance of M. douglasi, and it was noted that the cumulative interactions of these three parameters were significant. The photoperiods were highly significant. Relatively high statistical significance was also derived in the interaction between the prey size and photoperiod. There was no statistical significance between predator’s sex and prey size and predators’ sex and photoperiod, and when all three parameters interacted, very less significance occurred.

Prey availability and foraging activity by tundra-nesting sea ducks: Strong preference for specific wetland types.

Wetlands in Arctic tundra support abundant breeding waterbirds. Wetland types differing in area, depth, vegetation, and invertebrate biomass density may vary in importance to birds, and in vulnerability to climate change. We studied availability and use of different wetland types by prelaying females of four species of sea ducks (Mergini) breeding on the Arctic Coastal Plain of Alaska, USA: long-tailed ducks (Clangula hyemalis) and Steller's (Polysticta stelleri), spectacled (Somateria fischeri), and king eiders (Somateria spectabilis). All four species preferred shallow vegetated wetlands versus deeper lakes. The ducks spent almost all their active time feeding, but their occurrence in different wetland types was not affected by the relative biomass density of known prey or of all invertebrates that we sampled combined. Sea ducks strongly preferred wetlands dominated by emergent and submersed Arctophila fulva over those dominated by the sedge Carex aquatilis, despite the much greater number, total area, and invertebrate biomass density of Carex wetlands. The hens depend heavily on local invertebrate prey for protein to produce eggs; thus, their preference for Arctophila wetlands likely reflects greater accessibility of prey in the near-surface canopy and detritus of Arctophila. Such shallow wetlands decreased substantially in number (-17%) and area (-30%) over 62 years before 2013 and appear highly susceptible to further declines with climate warming. Impacts on sea ducks of climate-driven changes in availability of important wetland types will depend on their adaptability in exploiting alternative wetlands.