Changes in Spring Arrival and Fall Departure Dates of Migratory Birds as an Indication of Local Climate Change: A…

Changes in Spring Arrival and Fall Departure Dates of Migratory Birds as an Indication of Local Climate Change: A phenological study of New York State's Capital Region using citizen science

Biology

Townsend, Olivia C.

Garver, John

6/1/2014

Climate change is becoming an increasingly important topic of scientific research, and studies commonly analyze biological indicators. Migratory birds are responsive to environmental changes because life cycles depend on finding proper seasonal locations. eBird is a citizen science database launched by the Cornell Lab of Ornithology and National Audubon Society in 2002, and this study focused on eBird data to analyze migratory shifts over the past two decades for the Green-winged Teal (Anas crecca), Northern Pintail (Anas acuta), Bufflehead (Bucephala albeola), Common Goldeneye (Bucephala clangula), Common Merganser (Mergus merganser), Red-breasted Merganser (Mergus serrator), Canada Goose (Branta canadensis), Snow Goose (Chen caerulescens), Barn Swallow (Hirundo rustica), and Tree Swallow (Tachycineta bicolor ) in the Capital Region of New York State. Historical data sets from the early and mid-1900's were also used to make qualitative comparisons to past observations. Small changes in temperature and ice dynamics are already taking place in New York State, and observations of bird abundance and timing of migration may be reflecting climate change on a local scale. Plots were made using abundance data from eBird for Albany, Rensselaer, Saratoga, Schenectady, and Washington counties and evaluated in five?year time slices and decadal slices between 1995-2013. Overall, there has been advancement and delay in spring and fall migrations. The Barn Swallow and Tree Swallow show roughly a two?week advancement in spring arrival since the earlier decade. The Barn Swallow appeared to linger two weeks longer in the fall in the last decade, but sufficient data were not available for the Tree Swallow to make comparisons. The Green-winged Teal and Northern Pintail showed similar spring arrival dates between the two decades and an earlier fall departure by about two weeks in the later decade. The Common Goldeneye, Common Merganser, and Canada Goose displayed an opposite trend with a two- to three?week earlier spring arrival in the later decade and comparable fall departures between decades. The Bufflehead appeared to be arriving in the Capital Region approximately a month later in the more recent decade with a similar fall departure for both. Data were relatively sparse for the Snow Goose, and therefore migration dates for the two decades could not be compared. However, with the data available it appeared the Snow Goose decreased its length of time in the region. The Red-breasted Merganser is uncommon in this area, and there were essentially no sightings in the earlier decade. Thus, the slight increase may reflect a change in distribution. Avian migration is a complex behavior undoubtedly influenced by climatic conditions. These can either have direct impacts by affecting open water availability or indirect impacts by altering plant activity and insect abundance. Other factors like photoperiod, territorial competition, and risk of pre-breeding mortality must be recognized as affecting migration in addition to climate.

thesis

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