Climate and Food Synchronize Regional Forest Bird Abundances

Abstract

Analysis of synchrony in population fluctuations can help to identify factors that regulate populations and the scales at which these factors exert their influence. Using 15 years of data on the abundances of songbirds at four replicate forest sites in New Hampshire, USA, we addressed two main questions: (1) Are forest bird populations synchronous at the scale measured (tens of kilometers), and if so, (2) what environmental factors are responsible for the synchrony? Nine of the 10 bird species we examined exhibited significant spatial synchrony across the four sites. Within nesting and foraging species groups, tree nesters and foliage gleaners exhibited the highest spatial synchrony. Long‐distance (Neotropical) migrants exhibited higher spatial synchrony than did short‐distance migrants or year‐round residents. Synchrony within and among six species of long‐distance, migratory, insectivorous birds was correlated with synchronous fluctuations in the abundance of lepidopteran larvae, a primary food type during the breeding season, which in turn have been shown to be influenced by El Niño/La Niña global climate patterns. Abundances of year‐round resident species were related to another large‐scale climatic phenomenon, the North Atlantic Oscillation. Winter weather can have both direct (e.g., via temperature‐mediated mortality) and indirect (e.g., via winter food availability) effects on year‐round resident species. We do not believe that predation on adults or nests accounted for the observed synchrony. Dispersal among regional populations in this system may have played a role but is likely a product of the influence of regionally synchronous caterpillar fluctuations on bird reproduction. Long‐term regional population trends may have contributed to the observed synchrony for some species, but we do not consider these trends to be primary factors. Our findings of population synchrony support the importance of food and climate in influencing forest bird abundances and have broad implications for potential responses of bird and insect populations to climate change.

Climate change and its impact on Australia's avifauna

“…Taylor and Wilson 1990;Fraser et al 1992;Ainley 2002;Bergstrom 2003) but not others (Cunningham and Moors 1994;Kaiser 1997;Barbraud and Weimerskirch 2001;Woehler et al 2001;Ainley 2002). Population trajectories (and breeding phenology) in several species of land birds have been associated with long-term changes in large-scale meteorological phenomena, such as the Pacific decadal oscillation (Ballard et al 2003), the North Atlantic oscillation (Forchhammer et al 1998;Stenseth et al 2002;Jones et al 2003) and the ENSO (Boersma 1998;Stenseth et al 2002); the precise nature of the influence of climate change on these events is currently unknown. Examination of population trends in 77 species of common birds in France over the period [1989][1990][1991][1992][1993][1994][1995][1996][1997][1998][1999][2000][2001][2002] indicated that species with northern breeding distributions were more likely to have declined than those with southern distributions (Julliard et al 2004).…”

Plasma carotenoid levels in passerines are related to infection by (some) parasites

“…As previously commented, carotenoids should be obtained from an animal's diet and in the case of birds both invertebrates and fruit are important sources of carotenoids. Both of these resources undergo significant annual and seasonal oscillations in abundance (Herrera et al, 1998;Jones et al, 2003) that may explain our results. Both the effects of year and season have been already reported in the case of the Great Tit Parus major, the only species in which seasonal and annual variation in plasma carotenoids has been studied to date (Isaksson et al, 2007).…”

Egyes időjárási tényezők hatása a barátposzáta (Sylvia atricapilla) költési sikerére

“…Egyes területeken a több fészkelő madár átlagosan kevesebb fiókát tud felnevelni a megnövekvő intrapopulációs forráskompetíció miatt. A klímaváltozás következtében egyes táplálék rovarfajok populációi csökkenő trendet mutatnak, ami szintén hatással lehet az erdei énekesmadárfajok, így a barátposzáta költési sikerére is (JONES et al, 2003;BOTH & VISSER, 2005). A költési siker, a kompetíció mértéke élőhelyfüggő (WEIDINGER, 2000), erre következtethetünk azon eredményeinkből is, mely szerint a két vizsgálati területen tapasztalt produktivitási értékek évenkénti alakulása között nincs szignifikáns korreláció.…”

“…Csapadékösszegre vonatkozó szignifikáns korrelációkat csak a második költés esetében tudtunk kimutatni, ahol a júniusi negatív irányú kapcsolat a fészekpusztulások miatti mortalitást jelezheti, míg a júliusi pozitív kapcsolat a táplálékbőséggel hozható összefüggésbe (JONES et al, 2003). Egy angliai hosszú távú, több fajra vonatkozó vizsgálat (PEARCE-HIGGINS et al, 2015) szintén kimutatta, hogy egyes énekesmadárfajok érzékenysége a hőmérsékletre jobban meghatározta a költési sikert, mint a csapadékösszeg mértéke.…”