Spending time with the offspring is beneficial for development and can be a lifeboat for the finches of the Galapagos Islands, as a group of experts from Flinders University has recently shown.
A new study, published in the Proceedings of the Royal Society B, has found evidence that female Darwin’s finches that spend more time inside the nest can better protect from the larvae of vampire flies , which are deadly to growing chicks, as They are literally your food.
According to the investigation, the mother acts as a shock absorber and thereby saves their lives. Especially during the first few days after hatching, at which time the chicks are blind, defenseless, and unable to groom themselves . The older hatchlings still have to deal with the larvae, but they already have the ability to preen and shed intruding carnivores in this way. They even occasionally eat some in their personal maintenance tasks. The predator turned into prey.
“The male is also critical to the success of the chicks. If you feed the offspring a lot, the mother can stay inside the nest for longer, ”says Sonia Kleindorfer, professor at Flinders University and associated with the University of Vienna.
Timing is everything. The female must give up looking for food by herself and her presence is strongly influenced by the good supply of food from the male ”.
The avian vampire fly ( Philornis downsi ) was unintentionally introduced and is an invasive species in the Galapagos Islands. They take advantage of the absence of the parents of Darwin’s finches to enter the nests. It is similar in size and appearance to the common house fly. It is generally dark in color. Males usually have yellow legs and females darker. Adult flies feed on fruit and nectar . But they lay their eggs in bird nests or directly on the chicks . They take between one and two days to hatch, after which the larvae feed on the blood and tissues of the young chicks . Even inside the nostrils. After seven days the larvae pupate at the base of the nests and emerge as flies fourteen days later.
Indeed the introduction in the Galapagos Islands was accidental, in 1964. The Charles Darwin Foundation makes great efforts to effectively mitigate the threat of Philornis downsi , but at present there are no known techniques to achieve this.
British naturalist Charles Darwin’s theory of evolution by natural selection was developed while observing plants and animals in various settings, including the Galapagos Islands. There he noticed in 1835 the great diversity of endemic plants, birds and reptiles. And, among all the animals studied, the finches stand out. The 17 species of Darwin’s finches of the Galapagos Islands are a book example of rapid evolutionary adaptation, as each species has a unique beak shape suitable for extracting resources from a different ecological niche. Since Darwin’s finch nests were first observed in 1997, the avian vampire fly has been parasitizing chicks and changing their beaks and behavior.
The flies lay eggs that hatch into larvae, which in turn feed on the developing chicks. In this process, they kill most of the parasitized chicks or cause the beak of the survivors to be deformed.
“What we show in this publication is that the time spent by females in the nestling of the chicks predicts the number of parasites in the nest,” says Kleindorfer.
“The findings of the new research are significant because they show that ‘just being there’ can be a form of first-line defense against threats to the survival of offspring.”
So female Darwin’s finches provide nest care for younger than male pups and need their presence to defend themselves against parasites. For this reason, the survival of the females is compromised. Monitoring female survival is often more difficult than for males, as male Darwin’s finches produce a loud tune that females do not. Generally, we think that active defending males contribute more to offspring survival than females who incubate the eggs or chicks, says Andrew Katsis, a researcher at Flinders University.
“From long-term monitoring of Darwin’s finches we know that annual survival in females is much lower than in males, and more than 50% of male Darwin’s finches sing in nests without attracting females.”
“Control measures are urgently needed to save Darwin’s finches from extinction,” scientists say in a new publication in Birds.
The researchers found that only 10.4% of critically endangered medium tree finch (Camarhynchus pauper ) nests produced young on Floreana Island. The rest were wiped out by predators or parasites.
The article Female in-nest attendance predicts the number of ectoparasites in Darwin’s finch species has been published in December 2021 and is signed by Sonia Kleindorfer, Lauren K Common, Jody A O’Connor, Jefferson Garcia-Loor, Andrew C Katsis, Rachael And Dudaniec, Diane Colombelli-Négrel and Nico M Adreani.
The second article, also from December, is titled Nesting Success and Nesting Height in the Critically Endangered Medium Tree Finch ( Camarhynchus pauper ), has been published in Birds and is signed by Sonia Kleindorfer, Lauren K Common and Petra Sumasgutner.
