Inferring interactions between populations of different species is a challenging statistical endeavour, which requires a large amount of data. There is therefore some incentive to combine all available sources of data into a single analysis to do so. In demography and single-population studies, Integrated Population Models combine population counts, capturerecapture and reproduction data to fit matrix population models. Here, we extend this approach to the community level in a stage-structured predator-prey context. We develop Integrated Community Models (ICMs), implemented in a Bayesian framework, to fit multispecies nonlinear matrix models to multiple data sources. We assessed the value of the different sources of data using simulations of ICMs under different scenarios contrasting data availability. We found that combining all data types (capture-recapture, counts, and reproduction) allows the estimation of both demographic and interaction parameters, unlike count-only data which typically generate high bias and low precision in interaction parameter estimates for short time series. Moreover, reproduction surveys informed the estimation of interactions particularly well when compared to capture-recapture programs, and have the advantage of being less costly. Overall, ICMs offer an accurate representation of stage structure in community dynamics, and foster the development of efficient observational study designs to monitor communities in the field.L stages per species requires estimation of (S × L) 2 interaction parameters; this may be why unstructured statistical models for interaction between species have so far been preferred (Ives et al., 2003), at least when a single type of data is used (e.g., time series of counts, Dennis et al.
1995). Although nonlinear MPMs have many parameters, because of their internal age-structure, they also have advantages over unstructured discrete-time models currently fitted to data (i.e., discrete-time Lokta-Volterra or log-linear autoregressive modelling; Ives et al. 2008; Mutshinda et al. 2009; Hampton et al. 2013). Indeed, the survival rates expressed in MPMs are well estimated by capture-recapture techniques (Caswell, 2001; Lebreton et al., 2009). This opens new avenues tofit nonlinear matrix models for multiple species, by considering other types of data than just counts of species, such as data on survival and development rates, as well as reproduction. One approach to incorporate such demographic datasets, used in plant community dynamics, is to fit separate models for reproduction and survival components of the demography (Adler & HilleRisLambers, 2008;Chu & Adler, 2015), and then simulate the community-level model thus created, to evaluate its prediction of the counts and spatial structure. While this approach is sound, it does not take full advantage of opportunities to combine vital rate data with counts, which might be problematic for small datasets.Capture-recapture and reproduction data can be combined advantageously with counts within the Integrated Population ...