# Spatial Variation in Body Condition of a Coastal Sentinel, the Little Penguin, Reflects Marine and Terrestrial Factors

## TL;DR

Little penguins in eastern Tasmania are healthier than those in the north, with marine productivity and habitat loss affecting their body condition.

## Contribution

This study reveals sex-based and environmental influences on penguin health across multiple populations using Bayesian modeling.

## Key findings

- Eastern penguin populations have better body condition than northern ones.
- Marine productivity strongly positively correlates with penguin body condition.
- Habitat loss and parasite load negatively affect penguin health, especially in females.

## Abstract

Seabirds are widely considered sentinels of their coastal ecosystems. However, biological associations between specific marine and terrestrial factors and seabird health are less well understood. Here, we investigate the associations between habitat‐scale processes and variability in body condition of breeding little penguins
Eudyptula minor, across 15 populations in Lutruwita/Tasmania, Australia. Sites represent a range of nesting habitats, oceanographic conditions and localised anthropogenic disturbance, providing an unparalleled opportunity to assess the impact of multiple processes shaping health. We show significant regional differences in body condition, with eastern populations consistently in better body condition than northern. Using Bayesian multilevel models, we found marine productivity to have the strongest relationship (coef. 0.52, 95% CI [0.13, 0.91]). Body condition was also negatively related to habitat loss, expressed as total road length around the colony, and ectoparasite load, with parasitism having a greater negative association in females. By assessing health across a spatially robust number of populations, rarely performed in seabirds, we reveal marine, terrestrial and sex relationships, indicating potentially important processes shaping health that would otherwise be difficult to discern.

We detected spatial heterogeneity in the early breeding body condition of a coastal resident, the little penguin. Using Bayesian hierarchical modelling, we looked at several different environmental variables and their associations with conditions. We found differing sex‐based associations and that local marine productivity had the strongest positive association with condition, but urbanisation and parasite load were negatively associated with condition.