Many bird species enjoy far greater longevity than mammals of a similar size. Some modestly-sized birds, such as crows and ravens, can live for almost half a century when sheltered from the harsh realities of a wild life. What is the root of this avian longevity? A recent paper makes the case for greater resistance to oxidative damage:
Current mechanistic theories of aging would predict that many species of birds, given their unusually high metabolic rates, body temperatures, and blood sugar levels, should age more rapidly than mammals of comparable size. On the contrary, many avian species display unusually long life spans.
This finding suggests that cells and tissues from some avian species may enjoy unusually robust and/or unique protective mechanisms against fundamental aging processes, including a relatively high resistance to oxidative stress. We therefore compared the sensitivities of presumptively homologous epithelial somatic cells derived from bird and mouse kidneys to various forms of oxidative stress.
When compared to murine cells, we found enhanced resistance of avian cells from three species (budgerigars, starlings, canaries) to 95% oxygen, hydrogen peroxide, paraquat, and gamma-radiation. Differential resistance to 95% oxygen was demonstrated with both replicating and quiescent cultures. Hydrogen peroxide was shown to induce DNA single-strand breaks. There were fewer breaks in avian cells than in mouse cells when similarly challenged.
You might recall that greater resistance to oxidative damage - due to differing rations of biochemicals in cell membranes - is also the present consensus explanation for the outsize longevity of naked mole-rats in comparison to other rodent species.