Biomarkers of Animal Nutrition: From Seasonal to Lifetime Indicators of Environmental Conditions.

Nutrition underpins survival and reproduction in animal populations; reliable nutritional biomarkers are therefore requisites to understanding environmental drivers of population dynamics. Biomarkers vary in scope of inference and sensitivity, making it important to know what and when to measure to properly quantify biological responses. We evaluated the repeatability of three nutritional biomarkers in a large, iteroparous mammal to evaluate the level of intrinsic and extrinsic contributions to those traits.

Migration distance and maternal resource allocation determine timing of birth in a large herbivore.

Birth timing is a key life-history characteristic that influences fitness and population performance. For migratory animals, however, appropriately timing birth on one seasonal range may be constrained by events occurring during other parts of the migratory cycle. We investigated how the use of capital and income resources may facilitate flexibility in reproductive phenology of migratory mule deer in western Wyoming, USA, over a 5-yr period (2015-2019).

Drought reshuffles plant phenology and reduces the foraging benefit of green-wave surfing for a migratory ungulate.

To increase resource gain, many herbivores pace their migration with the flush of nutritious plant green-up that progresses across the landscape (termed "green-wave surfing"). Despite concerns about the effects of climate change on migratory species and the critical role of plant phenology in mediating the ability of ungulates to surf, little is known about how drought shapes the green wave and influences the foraging benefits of migration. With a 19 year dataset on drought and plant phenology across 99 unique migratory routes of mule deer (Odocoileus hemionus) in western Wyoming, United States, we show that drought shortened the duration of spring green-up by approximately twofold (2.

Spatial memory shapes migration and its benefits: evidence from a large herbivore.

From fine-scale foraging to broad-scale migration, animal movement is shaped by the distribution of resources. There is mounting evidence, however, that learning and memory also guide movement. Although migratory mammals commonly track resource waves, how resource tracking and memory guide long-distance migration has not been reconciled.

Where to forage when afraid: Does perceived risk impair use of the foodscape?

The availability and quality of forage on the landscape constitute the foodscape within which animals make behavioral decisions to acquire food. Novel changes to the foodscape, such as human disturbance, can alter behavioral decisions that favor avoidance of perceived risk over food acquisition. Although behavioral changes and population declines often coincide with the introduction of human disturbance, the link(s) between behavior and population trajectory are difficult to elucidate.

Migratory plasticity is not ubiquitous among large herbivores.

The migratory movements of wild animals can promote abundance and support ecosystem functioning. For large herbivores, mounting evidence suggests that migratory behaviour is an individually variable trait, where individuals can easily switch between migrant and resident tactics. The degree of migratory plasticity, including whether and where to migrate, has important implications for the ecology and conservation of large herbivores in a changing world.

The greenscape shapes surfing of resource waves in a large migratory herbivore.

The Green Wave Hypothesis posits that herbivore migration manifests in response to waves of spring green-up (i.e. green-wave surfing).