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Molts & plumages

Bird molt represents a key investment in self-maintenance and is readily shaped by environmental conditions. As such, I study variation in molt from temperate and tropical systems to determine how environment shapes molt strategies (characterized by changes in timing, extent, insertions, and duration) contributing to life history variation and adaptation to diverse ecological conditions.


Additionally, age-related variation in molt extent allows us to place individual birds into discreet age categories. Age classification is often necessary to understand variation in survival and dispersal. The calendar-based age classification system (widely used in North America) separates age classes based on hatch date relative to January 1st which, unfortunately, renders the system useless in tropical systems where breeding seasons often overlap January 1st. Based on relationships between molt extent and bird age, we developed a universal system of bird-age classification called the WRP system.

To help ornithologists effectively use the WRP system in the field and museum, I created a tutorial with photographic examples that reflect the majority of molt patterns exhibited by resident Neotropical birds. I will be adding photographic examples from North American as well as representative birds from central and east Africa in the near future. Make sure that you are familiar with the WRP system before reviewing photographic examples.

Click here to learn more about using the WRP system.


Click here to view examples of age classification using the WRP system


Click here to read Jared's blog on "Advanced WRP: new codes to better classify bird age" 


"Molt in Neotropical Birds" details molt strategies of tropical families, and provides detailed age and sex accounts for nearly 200 species.

Documenting novel molt patterns, such as this eccentric prealternate molt in an Indigo Bunting, provides insight into life history variation across birds.

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