Physiological and behavioral processes interact with environmental conditions to strongly influence organismal life history strategies which covary with latitude. However, few studies have articulated explicit linkages between metabolism and life history across latitudinal gradients. Interactions between metabolism and resource dynamics may give rise not only to patterns of variation in mean life history traits, but also to patterns in the ranges (diversity) of those traits across the same gradients. Here we show that the range of viable and realized metabolic/life history strategies covaries with the amplitude of seasonal resource fluctuations and, thus, latitude. Using a theoretical metabolic model we predicted that aseasonal environments support a greater diversity of life-history strategies than those subject to strong seasonality, where only 'fast' strategies were successful. We analyzed a global database of organismal metabolic parameters (estimated using a standard dynamic energy budget model) and found empirically derived evidence supporting our theoretical prediction that life history diversity negatively covaries with resource seasonality. These results comprise a novel framework for exploring covariation of life history with latitude at global scales, which may in turn help to explain other fundamental ecological patterns such as species diversity across gradients of seasonality.
Understanding the migratory movements and habitats used during the annual cycle of migrants is essential to developing comprehensive conservation strategies. Mountain Plovers (Charadrius montanus) are short‐distance migrants listed as a species of conservation concern in many states across their range, however, little is known about their migratory ecology. We used data from geolocators to describe the first direct estimates of migratory routes and migration schedules for Mountain Plovers breeding in Phillips County, Montana. We attached geolocators to 36 Mountain Plovers in 2010–2012 and recovered five (13.9%; three males and two females). Four of five Mountain Plovers in our study overwintered in Texas, and one overwintered in Arizona. Migration routes were relatively linear, with the exception of one plover that moved south and then west to reach its winter range in Arizona. Two plovers left breeding areas in mid‐July and the other three left in late September. All plovers used stopover sites near either eastern Colorado or southwest Kansas. Plovers that departed earlier used stopover sites for ~100 d, whereas those that left later used them for ~35 d. All plovers in our study arrived in wintering areas by early November and departed by late March. Our results suggest that eastern Colorado and southwest Kansas are important stopover areas during migration, and highlight the need to better understand how these locations support non‐breeding plovers.
Application of stable isotopes to study movement ecology and diet variation in a migratory songbird. Journal of Field Ornithology. Accepted. https://journal.afonet.org/volXX/issYY/artZZ/ Individual posterior probability assignment maps for group G1 including δ²Hf values ranging from -175.6‰ to -160.2‰ (M = -167.1‰, SD = 5.02‰, N = 18). The red dot on the map represents the sampling site in Oklahoma.
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