m.r.Life ι**=7/3ψ

Bird & Mammal Populations

Aim and Scope

Life history traits define not only the natural selection fitness of individuals, but also the growth of populations. Estimates of their variation are essential to progress evolutionary understanding, population dynamic modelling, and ecological management.

Our abilities in these areas improve with the completeness of estimates, but life history data are incomplete or missing for most species. Bird & Mammal Populations (BMP) aim to fill this gap by estimating life history and population dynamic models with no missing parameters, covering most species of birds and mammals in the world (Witting, 2024).

These models are used in natural selection analyses that decompose and reconcile much of the inter-specific life history variation by a few axes of natural selection (Witting, 2023a). They form the base of timeseries analyses that decompose population dynamic regulation into density regulation and population dynamic feed-back selection (Witting, 2023b). The resulting models are available in the Population Dynamic Simulator, where you can construct you own population dynamic predictions given habitats that fragment or improve. The estimates can also be downloaded under a Creative Common NonCommercial ShareAlike International License (CC BY-NC-SA 4.0).

Fig. 1 The estimation of missing parameters is cross-validation optimised to provide the best prediction of the available data. Estimation levels: genus (blue), family (green), order (yellow), and class (red). Witting (2024).

Estimation and uncertainty

Each of the 16,123 life history models in BMP reconciles the physiology and demography of a species with the intra-specific interactive foraging ecology at the naturally selected population dynamic equilibrium. The estimation of these models is based on Malthusian relativity, which is the only natural selection theory available that predicts the inter-specific variation of the body mass allometries from the natural selection of metabolism and mass (Witting, 1995, 2017a,b).

The theoretically predicted and empirically observed body mass allometries are combined in a joint inter-specific extrapolation that estimates the missing life history and ecological parameters for all species with body mass data (Witting, 2024). This estimation is cross-validation optimised to provide the best estimates of the available data, using estimators at the lowest phylogenetic level with data (Fig. 1). The precision of the data estimation is converted into uncertainty measures of the estimated missing parameters (Table 1), with an overall precision of about 28%.

Table. 1 The average uncertainty of estimated missing parameters, given by the standard deviations of the log ratios between data and their cross-validation predicted values (a cv like measure). From Witting (2024).

Data and sources

BMP is based on the Birdlife (2015) taxonomy for birds and the MDD (2023) taxonomy for mammals, with some subspecies with separate body mass estimates categorised as species.

The input data for model estimation is obtained from more than 600 independent literature sources. These include databases like i) AnAge that document longevity and life history traits across the tree of life (De Magalhaes et al., 2009), ii) PanTHERIA that focusses on life history, ecology, and geographical variation among mammals (Jones et al., 2009), iii) Myhrvold et al. (2015) who collect life history data for birds, mammals, and reptiles, iv) COMADRE that deals with demographic data and matrix population models that span a rich diversity of the animal kingdom world-wide (Salguero-Gomez et al., 2016), and v) AnimalTraits that focuses on the connection between body mass, metabolism, and brain size (Herberstein et al., 2022).

Other sources include body mass data from Smith et al. (2007), Dunning (2007), Weisbecker et al. (2013), and Tobias et al. (2021). Demographic traits on reproduction, time periods, and growth from Jetz et al. (2008) and del Hoyo et al. (1992�2011). Growth curve and survival data were obtained from an independent literature search, including survival estimates from McCarthy et al. (2008), DeSante and Kaschube (2009), Ricklefs et al. (2011), del Hoyo et al. (1992�2011), Wilson and Mittermeier (2009�2014), and Beauchamp (2023). Ecological parameters included population densities from Damuth (1987) and Santini et al. (2018), and home range areas from Tucker et al. (2014), Tamburello et al. (2015), and Nasrinpour et al. (2017) with an independent literature search for marine mammals and bats. Basal metabolic rates were obtained primarily from McNab (2008) for mammals and from McKechnie and Wolf (2004) for birds, with field metabolism for both taxa from Hudson et al. (2013).



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