DOI: 10.5061/dryad.k3j9kd59k
title: Data from: Changes in waterfowl migration phenologies in central North America: implications for future waterfowl conservation

description: Globally, migration phenologies of numerous avian species have shifted
 over the past half-century. Despite North American waterfowl being well
 researched, published data on shifts in waterfowl migration phenologies
 remain scarce. Understanding shifts in waterfowl migration phenologies
 along with potential drivers is critical for guiding future conservation
 efforts. Therefore, we utilized historical (1955–2008) nonbreeding
 waterfowl survey data collected at 21 National Wildlife Refuges in the
 mid- to lower portion of the Central Flyway to summarize changes in spring
 and autumn migration phenology. We examined changes in the timing of peak
 abundance from survey data at monthly intervals for each refuge and
 species (or species group; n = 22) by year and site-specific temperature
 for spring (Jan–Mar) and autumn (Oct–Dec) migration periods. For spring (n
 = 187) and autumn (n = 194) data sets, 13% and 9% exhibited statistically
 significant changes in the timing of peak migration across years,
 respectively, while the corresponding numbers for increasing temperatures
 were 4% and 9%. During spring migration, ≥80% of significant changes in
 the timing of spring peak indicated advancements, while 67% of significant
 changes in autumn peak timing indicated delays both across years and with
 increasing temperatures. Four refuges showed a consistent pattern across
 species of advancing spring migration peaks over time. Advancements in
 spring peak across years became proportionally less common among species
 with increasing latitude, while delays in autumn peak with increasing
 temperature became proportionally more common. Our study represents the
 first comprehensive summary of changes in spring and autumn migration
 phenology for Central Flyway waterfowl and demonstrates significant
 phenological changes during the latter part of the twentieth century.
description: Waterfowl survey data were collected by refuge personnel at the
 respective National Wildlife Refuges.
description: The file
 ‘AllCountData.xlsx’ contains all raw count data from waterfowl surveys at
 21 National Wildlife Refuges in the mid- to lower portion of the Central
 Flyway, USA, 1955–2008. Survey data consisted of both aerial and ground
 counts. Canada geese includes Canada Goose (<em>Branta
 canadensis</em>) and Cackling Geese (<em>B. hutchinsii</em>)
 and Light geese includes Snow Geese (<em>Anser
 caerulescens</em>) and Ross's Geese
 (<em>A.
 rossii</em>). Separate counts for Snow and Ross’s geese
 are included for the only refuge (Bitter Lake) that separated them during
 surveys. Total geese, swans, and ducks represent the sum of all goose,
 swan, and duck species, respectively. Missing values were propagated
 through summations so that any sum based upon a missing count value
 resulted in a missing value. The Comment field contains any pertinent
 information to the respective survey. Missing data are indicated by
 n/a.   The file
 ‘PeakAbundanceMonth.xlsx’ contains the phenological parameter ‘peak
 abundance month’ for spring (January–March) and autumn (October–December)
 migration seasons by year and average daily maximum temperature (Mean
 Daily Max Temp) for waterfowl at 21 National Wildlife Refuges in the mid-
 to lower portion of the Central Flyway, USA, 1955–2008. Peak abundance
 month was defined as the month with the highest monthly count average
 within the respective migration season (spring or autumn) and year for
 each species and refuge. Within each survey, all counts belonging to a
 waterfowl group for which the proportion of unidentified birds was
 indeterminable or exceeded 10% were excluded from the data set. Only
 species-refuge combinations with a total of at least 5 non-zero counts,
 fewer than 25% zero counts, and an average peak count of 200 birds or more
 for the migration season considered were included. Canada geese includes
 Canada Geese (<em>Branta
 canadensis</em>) and Cackling Geese (<em>B. hutchinsii</em>),
 Light geese includes Snow Geese (<em>Anser
 caerulescens</em>) and Ross's Geese
 (<em>A.
 rossii</em>), Goldeneyes includes Common and
 Barrow's Goldeneyes (<em>Bucephala
 clangula</em> and <em>B. islandica</em>),
 and Scaup includes Greater and Lesser Scaup (<em>Aythya
 marila</em> and <em>A. affinis</em>).
 Separate phenological data for Snow and Ross’s geese are included for the
 only refuge (Bitter Lake) that separated them during surveys. Missing data
 are indicated by n/a.