The Effect of Energy and Seasonality on Avian Species Richness and Community Composition

Abstract

We analyzed geographic patterns of richness in both the breeding and winter season in relation to a remotely sensed index of seasonal production (normalized difference vegetation index [NDVI]) and to measures of habitat heterogeneity at four different spatial resolutions. The relationship between avian richness and NDVI was consistent between seasons, suggesting that the way in which available energy is converted to bird species is similar at these ecologically distinct times of year. The number and proportion of migrant species in breeding communities also increased predictably with the degree of seasonality. The NDVI was a much better predictor of seasonal richness at finer spatial scales, whereas habitat heterogeneity best predicted richness at coarser spatial resolutions. While we find strong support for a positive relationship between available energy and species richness, seasonal NDVI explained at most 61% of the variation in richness. Seasonal NDVI and habitat heterogeneity together explain up to 69% of the variation in richness.

The distribution of species: occupancy, scale, and rarity

“…Knowledge about spatial distribution is essential for studying macroecological biodiversity patterns (Gaston, 1994;Gaston & Blackburn, 2000), for predicting the distribution of species in areas where observations are not available (Heikkinen & Hö gmander, 1994;MacKenzie et al, 2002;Raxworthy et al, 2003), for understanding environmental determination of species distribution (Currie, 1991;Lennon, Greenwoord & Turner, 2000;He, Zhou & Zhu, 2003;Hurlbert & Haskell, 2003), for assessing the effect of landscape fragmentation and climate change on extinction Fagan et al, 2005), and for planning biological conservation priority (Myers et al, 2000). However, the scale dependence of spatial distributions is sometimes considered as a statistical and ecological nuisance that prevents the prediction of species distribution across scales, thus hampering our ability to determine species' conservation status across scales.…”

Species–energy relationships at the macroecological scale: a review of the mechanisms

“…The latter is sometimes considered to be independent of energy availability and to rival it as an explanatory mechanism for species richness patterns (e.g. Williams, 1964 ;Kerr & Packer, 1997 ;Hurlbert & Haskell, 2003). However, the niche position mechanism provides a potential causal link between increased productive energy availability and increased habitat heterogeneity (Fig.…”

Environmental correlates of avian diversity in lowland Panama rain forests

“…Correlates of distribution patterns of bird species richness were examined using environmental variables known to be associated with species richness in the tropics (Gentry, 1982;Clinebell et at, 1995;Rosenzweig, 1995;Rahbek & Graves, 2001;Hurlbert & Haskell, 2003;Hawkins et at, 2005;Pautasso & Gaston, 2005). We did not consider temperature in our analyses because it varies little across the subregions; temperatures range daily and annually from 22 to 30°C throughout our study site; which is typical of lowland tropical rain forests (Garwood, 1983).…”

“…Patterns in the distribution of species diversity are the result of ecological, physical and historical factors across time and space (Vuilleumier & Simberloff, 1980;Currie & Paquin, 1987;Kerr & Packer, 1997;Hill & Hill, 2001;Hurlbert & Haskell, 2003;Hawkins et al, 2005Hawkins et al, , 2006. Whereas biogeographical history influences the characteristics of species assemblages and therefore puts bounds on the composition of local communities (Ricklefs, 2004), local community composition is also strongly affected by local environmental (abiotic and biotic) conditions (Ricklefs, 1987;Wiens & Donoghue, 2004).…”

“…Specific examples include the increase in plant and bird diversity with variation in mean annual rainfall (Gentry, 1982;Cueto & Lopez de Casenave, 1999;Gillespie & Walter, 2001;Hawkins et al, 2005;Schnitzer, 2005), topographic complexity and variability of elevation (Kerr & Packer, 1997;Kerr et al, 2001;Rahbek & Graves, 2001). Many potential explanations for diversity gradients have been proposed, including speciesenergy relationships (Hurlbert & Haskell, 2003;Hurlbert, 2004), habitat heterogeneity-animal species diversity relationships (Kerr & Packer, 1997;Tews et al, 2004) and historical factors (Ricklefs & Schluter, 1993;Ricklefs, 2004;Hawkins et al, 2006). Few studies have examined relationships across small geographical areas in the species-rich tropics.…”