Shifting baselines increase the risk of misinterpreting biodiversity trends

Ecological studies quantifying the impact of land-use change on biodiversity may be sensitive to the choice of reference points – or baselines – particularly when sampling across human land-use gradients and other space-for-time comparisons. Much depends on whether the chosen baseline has already undergone shifts in species composition because of hunting, habitat loss, and degradation. However, few studies have assessed the influence of shifting baselines on estimates of anthropogenic impacts. Using new survey data from five West African land-use gradients, we examine how habitat patch size and structure influence the estimated impact of land-use change on bird species richness and functional diversity. We show that smaller forests have already lost many forest-dependent birds, particularly those with large body size or specialised ecological niches, leading to reduced estimates of biodiversity loss after deforestation. The steepest biodiversity loss was found in mid-sized forests,..., , # Shifting baselines increase the risk of misinterpreting biodiversity trends

This DRYAD repository contains the code and data associated with the manuscript: Shifting baselines increase the risk of misinterpreting biodiversity trends published in the journal Ecography.

**Before you start**

To reconstruct our analyses, all our scripts are run through R and can be executed on a standard PC.

We have depended on the following R packages to produce analyses and figures:
glmmTMB
DHARMa
multcomp
psych
emmeans
scales
sf
geosphere
lwgeom
rgeos
sp
dplyr
ggplot2
ggeffects
tidyverse
patchwork
ggpubr

These should be installed before rerunning code (using \"install.packages(*name_of_packages*)\" in R). After installation, the required packages to run each script will be loaded automatically when the script is run.

#### **Data**

The Excel file `Data S1.xlsx` contains the raw survey data used in our analyses.

The Excel file is organised into the following sheets:

```
Data_S1.xlsx
├── Metadata
...,