Species in a Colorado subalpine ecosystem show subtle interdependences. Red-naped sapsuckers play two distinct keystone roles. They excavate nest cavities in fungus-infected aspens that are required as nest sites by two species of swallows, and they drill sap wells into willows that provide abundant

Many populations are heterogeneous collections of different sizes or stages of conspecifics. Existing overlap indices do not account for the size—/stage—structured nature of these populations. In this paper I present new overlap indices that use information about the sizes of individuals that co—occ

The larvae of Glaucopsyche lygdamus (Lepidoptera: Lycaenidae) secrete substances that attract ants. In two field sites in Colorado, tending ants protect caterpillars of G. lygdamus from attack by braconid and tachinid parasitoids. This protection may have been an important feature in the evolution o

The results suggest that yearling yellow-bellied marmots are more important for maintaining social cohesion than has previously been recognized, and that marmot colonies are largely organized based on age group and kinship.

The majority of flowering plants require animals for pollination, a critical ecosystem service in natural and agricultural systems. However, quantifying useful estimates of pollinator visitation rates can be nearly impossible when pollinator visitation is infrequent. We examined the utility of an in

Oviposition and emergence of a bivoltine population of B. bicaudatus in multiple stream reaches in one high-altitude watershed in western Colorado over 3 years was surveyed to determine whether hydrologic variation necessitated dispersal of females to find suitable oviposition sites and whether the

It is postulated that agonistic behaviour is one of the factors that limits the number of marmots on a colony site.

Female use of nutrients donated by males at mating, and complete sperm precedence, in Colias eurytheme Boisduval are documented.

The development of personality traits may facilitate animal’s coping with age-dependent requirements and constraints, and suggests an adaptive hypothesis: that these personality traits develop independently and at potentially age-appropriate times.

Aquatic insects have numerous adaptations reflecting the coevolution of predators and prey. Predators have a wide variety of search, capture, and consumption mechanisms, and prey demonstrate various physical, chemical, and behavioral defenses. Mortality in prey populations from predation may be sign

AbstractUnderstanding concentration‐discharge (C‐Q) relationships are essential for predicting chemical weathering and biogeochemical cycling under changing climate and anthropogenic conditions. Contrasting C‐Q relationships have been observed widely, yet a mechanistic framework that can interpret d

Redrock Lake is situated at 3,095 m in the subalpine zone on the east flank of the Front Range, Boulder County, Colorado. The lake lies on Pinedale moraine, and it contains 170 cm of organic sediments that overlie 10 cm of silty clay. The oldest of seven 14C dates from the organic sediment is 9,490

In high-elevation streams of western Colorado, mayflies (Baetis bicaudatus) develop faster, but mature at a smaller size where trout are present compared to streams where fish are absent. These life history traits reduce the time of larval exposure to trout predation, but cost reduced fecundity. We

Evidence is presented that discrimination occurs because white flowers have inferior ‘nectar guides’ and therefore require longer handling times than blue flowers, and pollinators may experience lower net rates of energy intake on white flowers, a sufficient reason for undervisitation by optimally-f

Although the empirical evidence lags behind the theoretical development, sex-allocation theory has been quite successful at predicting trends among populations.

Seasonal changes in the body weights of yellow-bellied marmot (Marmota flaviventris) populations were studied for 8 years in western Colorado. Marmots may be classified by size into four age groups: juvenile, yearling, 2-year-old, and 3-year-old or older, each group with significantly different mean

Strategies that enable species to persist in changing environments have historically been divided into ecological (distributional shifts and phenotypic plasticity) and evolutionary (adaptation and gene flow). However, most species will likely need to rely on a combination of approaches to mitigate

Snow is an important driver of ecosystem processes in cold biomes. Snow accumulation determines ground temperature, light conditions, and moisture availability during winter. It also affects the growing season’s start and end, and plant access to moisture and nutrients. Here, we review the current k

Variation in the degree of insect wing melanin affects thermoregulation, and is expected to be adapted to local environmental conditions, for example over an elevational gradient. The effects of melanization on flight activity and egg maturation rate were assessed in the closely related butterflies