Department of Natural Resource Ecology and Management, Oklahoma State University, 008C Ag Hall, Stillwater, Oklahoma, 74078, USA.
Ecology. 2018 Feb;99(2):289-299. doi: 10.1002/ecy.2102. Epub 2018 Jan 17.
Many terrestrial predators rely on olfaction to detect prey; therefore, prey should select habitat to reduce detectability of their odor cues. One way prey can potentially conceal their odor is by selecting locations with high turbulence and/or updrafts, conditions that disperse odor plumes and make odor sources difficult to locate. However, it is unclear how these conditions vary among vegetation cover types and which vegetative features drive them. We assessed variation and drivers of variables hypothesized to influence olfactory concealment (turbulence intensity and airflow slope) and experimentally evaluated whether these variables indeed influence predator detection of simulated prey. Specifically, we compared vegetation patch-scale values of turbulence intensity and airflow slope among grassland, shrubland, and forest and assessed relationships among these airflow variables and local-scale vegetative features within each vegetation type. Additionally, we experimentally investigated the importance of turbulence intensity, airflow slope, and visual concealment for predicting predator detection of scented quail eggs. In all vegetation types, we documented high variability in airflow conditions. At the patch scale, turbulence intensity was greater in shrubland and grassland than in forest, and updrafts were most common in shrubland whereas downdrafts were most common in grassland. Grassland was the only vegetation type with strong relationships among turbulence intensity and local vegetation features; both visual concealment and vegetation height were positively related to turbulence intensity. Additionally, persistence of scented quail eggs in grassland was best predicted by turbulence intensity; egg persistence increased with turbulence intensity. Our characterization of differences in olfactory variables among vegetation types provides an important step towards building a clearer understanding of olfactory landscapes. Further, our observation of both patch- and local-scale variation in olfactory variables suggests that prey can potentially select for olfactory concealment at multiple scales. We hypothesize that olfactory concealment provided by high levels of turbulence intensity is an important component of cover in grassland, and that in grassland/shrubland landscapes, prey selection of shrubland patches reduces odor detectability. Our finding of a positive relationship between turbulence intensity and visual concealment also suggests that olfactory concealment may be a previously underappreciated confounding factor in studies of habitat selection.
许多陆生捕食者依靠嗅觉来探测猎物；因此，猎物应该选择栖息地，以减少其气味线索的可探测性。猎物潜在地隐藏其气味的一种方法是选择具有高湍流和/或上升气流的位置，这些条件会分散气味羽流，使气味源难以定位。然而，目前尚不清楚这些条件在植被覆盖类型之间如何变化，以及哪些植被特征驱动了这些条件。我们评估了假设影响嗅觉隐蔽性的变量（湍流强度和气流斜率）的变化和驱动因素，并实验评估了这些变量是否确实影响了对模拟猎物的捕食者的探测。具体来说，我们比较了草地、灌丛和森林中斑块尺度上的湍流强度和气流斜率值，并评估了这些气流变量与每种植被类型内局部尺度植被特征之间的关系。此外，我们还实验研究了湍流强度、气流斜率和视觉隐蔽性对预测有气味鹌鹑蛋被探测的重要性。在所有植被类型中，我们记录了气流条件的高度可变性。在斑块尺度上，灌丛和草地中的湍流强度大于森林中的湍流强度，上升气流在灌丛中最为常见，而在草地中则最为常见。草地是唯一一种具有强烈的湍流强度与局部植被特征之间关系的植被类型；视觉隐蔽性和植被高度都与湍流强度呈正相关。此外，在草地中，有气味鹌鹑蛋的持久性受湍流强度的影响最大；随着湍流强度的增加，鸡蛋的持久性增加。我们对植被类型之间嗅觉变量差异的描述为建立对嗅觉景观的更清晰理解提供了重要步骤。此外，我们观察到嗅觉变量在斑块和局部尺度上的变化表明，猎物可能会在多个尺度上选择嗅觉隐蔽性。我们假设，高强度的湍流强度提供的嗅觉隐蔽性是草地中遮蔽物的一个重要组成部分，并且在草地/灌丛景观中，猎物对灌丛斑块的选择降低了气味的可探测性。我们还发现湍流强度与视觉隐蔽性之间存在正相关关系，这表明嗅觉隐蔽性可能是栖息地选择研究中一个以前被低估的混杂因素。
