Search for: All records

Abstract Climate change and its resulting effects on seasonality are known to alter a variety of animal behaviors including those related to foraging, phenology, and migration. Although many studies focus on the impacts of phenological changes on physiology or fitness enhancing behaviors, fewer have investigated the relationship between variation in weather and phenology on risk assessment. Fleeing from predators is an economic decision that incurs costs and benefits. As environmental conditions change, animals may face additional stressors that affect their decision to flee and influence their ability to effectively assess risk. Flight initiation distance (FID)—the distance at which animals move away from threats—is often used to study risk assessment. FID varies due to both internal and external biotic and physical factors as well as anthropogenic activities. We asked whether variation in weather and phenology is associated with risk-taking in a population of yellow-bellied marmots (Marmota flaviventer). As the air temperature increased marmots tolerated closer approaches, suggesting that they either perceived less risk or that their response to a threat was thermally compromised. The effect of temperature was relatively small and was largely dependent upon having a larger range in the full data set that permitted us to detect it. We found no effects of either the date that snow disappeared or July precipitation on marmot FID. As global temperatures continue to rise, rainfall varies more and drought becomes more common, understanding climate-related changes in how animals assess risk should be used to inform population viability models. 

Abstract Ecotourism provides an opportunity to experience nature that may promote its conservation. Ecotourists photograph wildlife, and photography plays an important role in focusing public's attention on nature. Although photography is believed to be a low‐impact activity, how the visual stimulus of cameras influences wildlife remains unknown. Since animals are known to fear eyes pointed towards them because of similarity to predator eyes, we predicted that cameras with zoom lens would increase vigilance. Using yellow‐bellied marmots (Marmota flaviventer) and adopting a behavioural approach to identify marmots' response to photography, we experimentally quantified proportion of time allocated to vigilance during foraging and flight initiation distance (FID, the distance at which a marmot started to flee from an approaching human) towards humans with and without a camera. We focused on time allocated to vigilance measured in three ways: the proportion of time when marmots moved their head and body towards observers (looking towards observer), the proportion of time when marmots moved their head away from observers (looking away from observer) and the total vigilance (sum of looking towards and away from observer). While a camera was pointed at a marmot, individuals allocated more time to looking towards the observer and less time to looking away from the observer than they did without a camera. However, the total proportion of time allocated to vigilance was not different when marmots were approached by humans with and without a camera. Additionally, whether or not an observer was carrying a camera had no effect on FID. Our results indicated that cameras distracted marmots but did not influence their subsequent risk assessment; marmots may be curious about cameras but were not threatened by them. However, capturing an individual's attention may reduce their ability to look out for predators and thus may increase vulnerability to predation. Regulating photography in locations where predation risk is high or vulnerable species ranges' overlap with humans may be required. 

Abstract Floral microbes, including bacteria and fungi, alter nectar quality, thus changing pollinator visitation. Conversely, pollinator visitation can change the floral microbial community.Most studies on dispersal of floral microbes have focused on bees, ants or hummingbirds, yet Lepidoptera are important pollinators.We asked (a) where are microbes present on the butterfly body, (b) do butterflies transfer microbes while foraging, and (c) how does butterfly foraging affect microbial abundance on different floret structures.The tarsi and proboscis had significantly more microbes than the thorax in wild‐caughtGlaucopsyche lygdamus(Lepidoptera: Lycaenidae) andSpeyeria mormonia(Lepidoptera: Nymphalidae).Glaucopsyche lygdamus, a smaller‐bodied species, had fewer microbes thanS. mormonia.As a marker for microbes, we used a bacterium (Rhodococcus fascians,near NCBI Y11196) isolated from aS. mormoniathat was foraging for nectar, and examined its dispersal byG. lygdamusandS. mormoniavisiting florets ofPyrrocoma crocea(Asteraceae). Microbial dispersal among florets correlated positively with bacterial abundance in the donor floret. Dispersal also depended on butterfly species, age, and bacterial load carried by the butterfly.Recipient florets had less bacteria than donor florets. The nectaries had more bacteria than the anthers or the stigmas, while anthers and stigmas did not differ from each other. There was no differential transmission among floral organs.Lepidoptera thus act as vectors of floral microbes. Including Lepidoptera is thus crucial to an understanding of plant–pollinator–microbe interactions. Future studies should consider the role of vectored microbes in lepidopteran ecology and fitness. 

Abstract Both theory and prior studies predict that climate warming should increase attack rates by herbivores and pathogens on plants. However, past work has often assumed that variation in abiotic conditions other than temperature (e.g. precipitation) do not alter warming responses of plant damage by natural enemies. Studies over short time periods span low variation in weather, and studies over long time‐scales often neglect to account for fine‐scale weather conditions.Here, we used a 20+ year warming experiment to investigate if warming affects on herbivory and pathogen disease are dependent on variation in ambient weather observed over 3 years. We studied three common grass species in a subalpine meadow in the Colorado Rocky Mountains, USA. We visually estimated herbivory and disease every 2 weeks during the growing season and evaluated weather conditions during the previous 2‐ or 4‐week time interval (2‐week average air temperature, 2‐ and 4‐week cumulative precipitation) as predictors of the probability and amount of damage.Herbivore attack was 13% more likely and damage amount was 29% greater in warmed plots than controls across the focal species but warming treatment had little affect on plant disease. Herbivory presence and damage increased the most with experimental warming when preceded by wetter, rather than drier, fine‐scale weather, but preceding ambient temperature did not strongly interact with elevated warming to influence herbivory.Disease presence and amount increased, on average, with warmer weather and more precipitation regardless of warming.Synthesis. The effect of warming over reference climate on herbivore damage is dependent on and amplified by fine‐scale weather variation, suggesting more boom‐and‐bust damage dynamics with increasing climate variability. However, the mean effect of regional climate change is likely reduced monsoon rainfall, for which we predict a reduction in insect herbivore damage. Plant disease was generally unresponsive to warming, which may be a consequence of our coarse disease estimates that did not track specific pathogen species or guilds. The results point towards temperature as an important but not sufficient determinant and regulator of species interactions, where precipitation and other constraints may determine the affect of warming. 

Abstract Leaf energy balance may influence plant performance and community composition. While biophysical theory can link leaf energy balance to many traits and environment variables, predicting leaf temperature and key driver traits with incomplete parameterizations remains challenging. Predicting thermal offsets (δ,T_leaf − T_airdifference) or thermal coupling strengths (β,T_leafvs.T_airslope) is challenging.We ask: (a) whether environmental gradients predict variation in energy balance traits (absorptance, leaf angle, stomatal distribution, maximum stomatal conductance, leaf area, leaf height); (b) whether commonly measured leaf functional traits (dry matter content, mass per area, nitrogen fraction, δ¹³C, height above ground) predict energy balance traits; and (c) how traits and environmental variables predictδandβamong species.We address these questions with diurnal measurements of 41 species co‐occurring along a 1,100 m elevation gradient spanning desert to alpine biomes. We show that (a) energy balance traits are only weakly associated with environmental gradients and (b) are not well predicted by common functional traits. We also show that (c)δandβcan be partially approximated using interactions among site environment and traits, with a much larger role for environment than traits. The heterogeneity in leaf temperature metrics and energy balance traits challenges larger‐scale predictive models of plant performance under environmental change. A freePlain Language Summarycan be found within the Supporting Information of this article. 

Abstract 1. Although associative learning is widespread across animals, its ecological importance is difficult to assess because learning is rarely studied in the field, where informative cues are juxtaposed against complex backgrounds of uninformative noise. 2. Ants rely heavily on chemical cues for foraging and engage in many ecologically important interactions with plants. Nevertheless, little is known about the role of associative learning of plant chemicals in ant foraging for carbohydrates. 3. In a field setting, the present study investigated whether the distantly related ant speciesFormica podzolica(Formicinae subfamily) andTapinoma sessile(Dolichoderinae subfamily) exhibited associative learning of the chemical cues from two co‐occurring plant species that are taxonomically and chemically distinct (Asteraceae:Helianthella quinquenervisand Apiaceae:Ligusticum porteri). 4. For two consecutive summers, ants were trained to forage from artificial sugar‐rich baits associated with the leaf chemicals from eitherH. quinquenervisorL. porterifor 24 h, after which a two‐choice test was deployed to assess whether ants would be more likely to select baits associated with the same (versus different) plant chemicals on which they had been trained. 5. The present study demonstrates associative learning of chemicals from both plant species, and these effects were consistent between ant species and years; training increased bait occupancy from 42% on the untrained scent to 66% on the trained scent. These results indicate that associative odour‐learning may be widespread across ants and serve as an important mechanism mediating ant selection of resources. 

Outdoor recreation benefits local economies, environmental education, and public health and wellbeing, but it can also adversely affect local ecosystems. Human presence in natural areas alters feeding and reproductive behaviors, physiology, and population structure in many wildlife species, often resulting in cascading effects through entire ecological communities. As outdoor recreation gains popularity, existing trails are becoming overcrowded and new trails are being built to accommodate increasing use. Many recreation impact studies have investigated effects of the presence or absence of humans while few have investigated recreation effects on wildlife using a gradient of disturbance intensity. We used camera traps to quantify trail use by humans and mid- to large-sized mammals in an area of intense outdoor recreation–the Upper East River Valley, Colorado, USA. We selected five trails with different types and intensities of human use and deployed six cameras on each trail for five weeks during a COVID-enhanced 2020 summer tourism season. We used occupancy models to estimate detectability and habitat use of the three most common mammal species in the study area and determined which human activities affect the habitat use patterns of each species. Human activities affected each species differently. Mule deer (Odocoileus hemionus) tended to use areas with more vehicles, more predators, and greater distances from the trailhead, and they were more likely to be detected where there were more bikers. Coyotes (Canis latrans) and red foxes (Vulpes vulpes) were most likely to use areas where their prey species occurred, and foxes were more likely to be detected where the vegetation was shorter. Humans and their recreational activities differentially influence different species. More generally, these results reinforce that it is unlikely that a single management policy is suitable for all species and management should thus be tailored for each target species. 

The distance at which animals move away from threats, flight initiation distance (FID), is often used to study antipredator behaviour and risk assessment. Variation in FID is explained by a variety of internal and external biotic and physical factors, including anthropogenic activities. Most prior studies focused on unidentified individuals, so our understanding of the fitness consequences of FID is relatively limited. We asked whether consistent individual differences in variation in flight initiation distance is associated with variation in summer survival and/or winter survival in an individually marked population of yellow- bellied marmots. We found no clear association between flight initiation distance and summer sur- vival or winter survival. This suggests that FID decisions, while demonstrably optimizing current survival, may not have longer-term fitness consequences. Our results may be explained by the relatively modest repeatability of FID or it may have emerged from our attempt to explain longer-term measures of fitness. Future studies of the fitness consequences of personality traits should pay particular attention to the time interval between measuring the individuality of a trait and examining its fitness consequences.