Avian Communication and Behaviour in Dynamic Environments.

行为灵活性可能使物种能够应对不断变化的或新的环境，我们将在入侵城市地区的山雀和麻雀物种中进行研究，这些物种将其范围扩展到新的地区，或者与密切相关（但通常是孤立的）物种接触。通过提供喂食器和巢箱，黑冠山雀、栗色背山雀和山山雀经常被吸引到城市绿地中定居，但这种定居使它们受到噪音水平增加和城市化相关栖息地改变的影响。虽然这些物种定居在城市空间，但它们改变发声的能力可能会影响它们补偿不同环境的能力。我们和其他研究表明，低频城市噪音掩盖了较低音调的发声，这有利于在定居的个人/群体中转向高频和更响亮的信号。黑冠山雀在春季主要使用远距离鸣叫来发出信号；山地山雀交替使用鸣叫和更短距离的啼叫；栗色背山雀不会唱歌，只会发出咕嘟咕嘟的叫声。利用便携式扬声器播放城市噪音，我们将测试雄性动态调整信号以避免掩蔽的能力，并确定调整灵活性是否因物种而异。我们还将测试雌性和雄性辨别嵌入城市噪音中的鸟类鸣叫的感知能力，以及已经在城市景观中定居的鸟类是否会发出不太容易被掩盖的鸣叫。城市发展和林业实践也会影响物种相互作用的可能性。黑冠山雀和山雀喜欢不同的栖息地，通常不会有重叠的分布。然而，接触点发生在海拔较低的落叶林（黑冠栖息地）与海拔较高的针叶林（山地栖息地）之间，这可能是由于城市化或林业相关的土地清理造成的。在一个接触种群中，山雀（从属物种）改变了它们的鸣叫和鸣叫方式，以避免与黑冠山雀的信号重叠。尽管有这些调整，我们发现雌性山山雀和雄性黑冠山雀之间的额外配对导致杂交后代出现在山山雀的巢中，而不是黑冠山雀的巢中。我们将使用遗传分析来探索这些模式在新研究人群中的普遍性，并确定杂交后代是否会减少或成年状态。我们将对黑冠山雀播放山雀的鸣声，以确定改变鸣声是否足以减少社会优势物种的攻击性。我们还将在山山雀的领地内播放黑顶山雀的鸣叫声，以确定鸟类是否在存在优势竞争对手的情况下动态调整信号。落基山脉北部的伐木和大坝建设可能是栖息地走廊的来源，这些栖息地走廊允许东部物种，如白喉麻雀，在不列颠哥伦比亚省中北部建立小规模的繁殖种群。这一小群西部麻雀唱着一种独特的方言，与加拿大东部常见的歌曲不同，这可能是西部麻雀的创始人效应与歌曲的行为学习相结合的结果。我们将结合基因分析、羽毛中独特的同位素水平和安装在候鸟身上的光感地理定位器背包，来确定落基山脉两侧的种群被隔离的程度，以及这如何影响这一边缘种群中歌曲方言的进化和传播。

Behavioural flexibility may enable species to cope with changing or novel environments, which we will investigate among chickadee and sparrow species that have invaded urban areas, expanded their range into novel regions, or come into contact with closely-related (but typically isolated) species. Black-capped, chestnut-backed and mountain chickadees are often attracted to settle in urban greenspace through provision of feeders and nestboxes, but such settlement subjects them to the increased noise levels and altered habitats associated with urbanization. Though these species settle in urban spaces, their capacity to alter vocalizations may affect their ability to compensate for the different environments. Our and other studies show low-frequency urban noise masks lower-pitched vocalizations, which would favour shifts to higher-frequency and louder signals among settling individuals/populations. Black-capped chickadees primarily use long-range songs during spring signalling; mountain chickadees alternate the use of song and shorter-range chick-a-dee calls; and chestnut-backed chickadees lack song and produce only chick-a-dee calls. Using portable speakers broadcasting urban noise, we will test the capacity of males to dynamically adjust their signals to avoid masking, and determine whether the flexibility to adjust differs between species. We will also test the perceptive ability of both females and males to distinguish songs of birds embedded in urban noise, and whether birds that have already settled in urban landscapes produce songs that are less easily masked. Both urban development and forestry practices can also affect likelihood of species interactions. Black-capped and mountain chickadees prefer different habitats and typically do not have overlapping distributions. However, contact sites occur where the lower-altitude deciduous forests (black-capped habitat) abut higher-altitude coniferous forests (mountain habitat), which can arise from land clearing associated with either urbanization or forestry . In one contact population, mountain chickadees (the subordinate species) alter their songs and song/call usage to avoid signal overlap with black-capped chickadees. Despite these adjustments, we found that extra-pair matings between female mountain and male black-capped chickadees resulted in hybrid young appearing in mountain, but not black-capped, nests. We will use genetic analysis to explore the generality of these patterns in new study populations, and determine whether hybrids suffer reduced offspring or adult condition. We will playback mountain chickadee songs to black-capped chickadees to determine whether altering songs is sufficient to reduce aggression from the socially-dominant species. We will also playback black-capped chickadee song bouts within territories of mountain chickadees to determine whether birds dynamically adjust signalling in the presence of a dominant competitor. Logging and dam construction in the northern Rockies have been implicated as the likely source of habitat corridors that have allowed eastern species, like white-throated sparrows, to establish small breeding populations in north central British Columbia. This small western population of sparrows sings a distinctive dialect from the common song heard throughout eastern Canada, and may result from founder effects of this western population coupled with behavioural learning of songs. We will use a combination of genetic analyses, distinctive isotope levels in feathers and light-sensing geolocator backpacks mounted on migrating birds to determine the degree to which populations on either side of the Rockies are isolated, and how this affects the evolution and spread of song dialects in this peripheral population.