Moreover, both captive and wild data probably underestimate actua

Moreover, both captive and wild data probably underestimate actual maximum life spans because in the field the recovery of very old, banded birds requires considerable luck, and in captivity mortality can result from accidents, animal care practices and inappropriate living conditions rather than senescence (e.g. Sherman & Jarvis, 2002). We were forced to use a single mass and longevity datum per species by lack of other information: intra-specific variation in life spans has been quantified for

only a few birds (e.g. Fox et al., 2006; Jones et al., 2008; Keller et al., 2008), and in the 11 data bases we buy LDK378 consulted (Appendices 1 and 2) body masses of males and females typically were not separated and the sex of the longest-lived individual usually was not specified. All our analyses assume that, like noise in a signal, deficiencies in the quality and quantity of maximum longevity data for individual species would increase variance and mask associations with ecological, physiological and behavioral variables that actually exist, but they would not generate associations that do not in fact occur. For

each species in our longevity data base we sought information on eight categorical variables that have been hypothesized to affect extrinsic mortality and senescence, using the following nine data sources: Cramp & Perrins (1977–1994), Animal Diversity Web (1995–2006), del Hoyo et al. (1997), Juniper (1998), Global Raptor Information Network (1999–2007), Longevity Records (2002), Birds in Backyards (2005), SCH727965 supplier Birds of North America Online (2005) and NatureServe (2008). These variables were: (A) Diet– Each species was categorized based on its typical diet as being a: (1) Carnivore; (2) Herbivore; (3) Omnivore. Ultimately, information on both continuous variables (maximum longevity and mean mass) and all eight categorical variables was available for 470 species (Appendix 2). This represents almost 5% of the world’s avifauna, and

we believe it is the largest data Plasmin base of its kind available. The Passeriformes was the most speciose order in our data base, containing complete information on 179 species in 17 families. We included this order in our comprehensive analysis and also analyzed the Passeriformes separately, to see if intra- and inter-order results corresponded; no other orders could be analyzed separately due to insufficient sample sizes. Initially we had planned to include ‘age at first reproduction’ in our multivariate analyses. However, we decided not to do so for two reasons. First, preliminary exploration of our data base revealed that age at first reproduction was so tightly correlated with mean mass (F=11.1727, d.f.=1314, P<1.29E−24) that the two variables could not be treated as independent. Second, age at first reproduction is more appropriately considered an effect rather than a primary cause of the environmental factors generally hypothesized to underlie variations in life spans and senescence rates.

Leave a Reply

Your email address will not be published. Required fields are marked *

*

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>