Hybrid Ravens and Taxonomic Puzzles: Untangling Australia’s Corvid Conundrum
Genomic evidence reveals unexpected hybridisation between Little and Australian Ravens, challenging long-held assumptions about species boundaries
Ravens with blurred lines
For generations, Australian birdwatchers have wrestled with the problem of telling ravens apart. The Australian Raven (Corvus coronoides), Little Raven (C. mellori), and Forest Raven (C. tasmanicus) look and sound remarkably similar, with only subtle differences in hackle shape, calls, and behaviour. Now, a comprehensive genomic study led by Anna Kearns and colleagues has revealed that the confusion runs deeper than field identification – hybridisation between these species is real, and their evolutionary history is more complex than previously thought.
Unexpected hybrids uncovered
By sequencing DNA from 94 specimens – both fresh tissues and historical museum skins – the team discovered several birds originally labelled as Australian Ravens that were, in fact, Little Ravens or hybrids between the two. This is the first confirmed evidence of hybridisation between C. coronoides and C. mellori, a finding that challenges past assertions that these species never interbreed. Some individuals showed clear genetic signatures of backcrossing, suggesting that hybrids can survive and reproduce, weaving genetic threads between the species.
Subspecies under scrutiny
The study also sheds new light on the contentious question of subspecies within the Australian Raven. Traditionally, two forms have been recognised: the widespread eastern C. c. coronoides and the south-western C. c. perplexus. Morphological and behavioural differences – such as throat hackle shape and flocking behaviour – have long hinted at a divide. However, the genomic data suggest only limited structuring, with much of the variation explained by geography and isolation-by-distance.
Intriguingly, the greatest genetic disjunction was detected not where earlier work had placed it, near South Australia’s Eyrean Barrier, but further west across the Nullarbor. This raises the possibility that C. c. perplexus is truly confined to the far south-west of Western Australia, potentially as a regional subspecies rather than a full species.
A taxonomic tangle
The findings reaffirm that Little and Forest Ravens are valid, distinct species. Yet the blurred boundaries within the Australian Raven lineage highlight the difficulties of drawing firm taxonomic lines in birds that have experienced both historical separation and later secondary contact.
The Kangaroo Island population, for example, appears genetically distinct, though researchers caution against hasty recognition of yet another subspecies. The broader message is that raven taxonomy remains unsettled, and that subtle differences in call, plumage, and size may not always reflect neat evolutionary divisions.
Implications for ornithology
Beyond classification debates, the study underscores how museum collections, when paired with modern genomics, can uncover hidden evolutionary stories. Birds collected over a century ago now reveal genetic secrets about hybridisation and population structure that were invisible to earlier naturalists.
For birders, the work is both a reassurance and a complication. It confirms why distinguishing Australian and Little Ravens in the field can be so tricky – they are not just lookalikes but sometimes genetic blends. For scientists, it highlights the dynamic nature of species boundaries and the importance of hybridisation in shaping avian evolution.
The raven’s lesson
In the end, these findings remind us that evolution is messy, and taxonomy is an attempt to impose order on a fluid process. Australia’s ravens, with their haunting calls and subtle differences, continue to defy simple categorisation – and in doing so, they offer a deeper lesson in the complexity of nature.
September 2025
Share this story
