Global Ecology and Conservation (Jun 2023)
Causes and consequences of demography in continent-scale, full-annual-cycle population dynamics under global change
Abstract
Population ecologists have long been challenged to understand the spatiotemporal variation in the causes and consequences of demography, which is particularly important for migratory species that experience vastly different environmental conditions throughout the annual cycle. Such understanding is also essential for developing effective and efficient conservation strategies under global changes. The northern pintail (Anas acuta) is a continentally distributed migratory species that showed a decreasing population trajectory which is distinct from most other North American waterfowl. The environmental drivers of demography, contributions of demography to population growth, and linkages between breeding regions remain poorly understood, hindering our ability to develop appropriate conservation strategies. The goal of this study is to understand the spatiotemporal variation in the effects of climate and land use changes on three pintail breeding populations in Alaska, Northern, and Prairie regions through demographic processes, which also allows us to identify populations that are self-sustainable. Using an integrated population model that jointly analyzed a half-century (1961–2019) of count and band-recapture-recovery data, we found that the effects of breeding-season climate on productivity differed among regions, yet preceding winter temperature negatively affected productivity in all regions. Furthermore, our results revealed the importance of productivity in both Alaska and Prairie in driving breeding population dynamics in these regions and at a continental scale. The last, we found that the Alaska and Prairie populations, but not the Northern population, were self-sustainable, likely due to different productivity levels in these regions. Our results indicated the importance of developing different conservation strategies among breeding regions, but also pointed out that conservation strategies that mitigate negative effects of climate change on wintering regions are likely to benefit all breeding populations. Our work provides unique insights about continent-scale, full annual cycle population dynamics of a migratory species of great conservation interest. Our modeling approach and results need to be broadly considered in studies that aim to assess the effects of global changes on population dynamics and conservation strategies.
