Healthy mum – eggcellent chicks
Tuesday 21 July 2009
Parents who eat their 5-a-day can help protect their chicks against parasites, reveals new research on the New Zealand hihi published today.
Scientists identified carotenoids in adult hihi diets as an important ingredient for counteracting the negative effects of the blood sucking mite Ornithonyssus bursa on their chicks.
Hihi mums with mite-invested nests were provided with a dietary supplement of carotenoids by the researchers. These birds then went on to raise broods that were as healthy as those from mums with mite-free nests.
Carotenoids give egg yolks their rich gold colour, so mums that lay golden eggs are giving their chicks the best chance of defending themselves against the mites.
“Carotenoids are naturally occurring biochemicals that perform important roles in animal health including enhancing the immune system and acting as strong antioxidants.
"Nestlings face a period of rapid and energetic growth where resources are ideally used to reach a point where they can fend for themselves.
"Carotenoids help support this rapid development and can also help when additional stressors such as parasites are experienced by developing young.” says ZSL's Dr John Ewen, lead author of the study.
He adds: “Our results add to extensive global research showing the beneficial roles carotenoids play in the health of both young and adult birds and other vertebrates.”
Fruit and vegetables are rich in carotenoids, so it’s important that hihi parents build nests in forests with high plant biodiversity, to ensure a healthy, balanced diet.
Once widespread across New Zealand’s North Island, the hihi is now endangered and confined to a single remnant population on the small offshore island of Little Barrier and a few additional populations recently established through reintroduction.
“Like many other island endemic bird species, the hihi has declined following European colonization due to the introduction of exotic mammalian predators and extensive loss of habitat as well as the possible spread of exotic diseases”, says Dr Phill Cassey, from the University of Birmingham’s Centre for Ornithology and co-author of the study.
This timely research highlights the need for conserving rich forest ecosystems, providing hihi with the food sources they need to lay ‘golden’ eggs.
The research paper, Maternally invested carotenoids compensate costly ectoparasitism in the hihi, is published online this week in the US journal Proceedings of the National Academy of Sciences (PNAS).