̽��ֱ�� of Cambridge - Claire Spottiswoode

Successful honey-hunters know how to communicate with wild birds

jg533 — Fri, 08 Dec 2023 09:04:57 +0000

Wild honeyguide birds prefer to cooperate with people who have learned local cultural traditions to find and access honey-filled bees’ nests, a new study has found.

Birds and honey badgers could be cooperating to steal from bees in parts of Africa

jg533 — Thu, 29 Jun 2023 11:27:19 +0000

̽��ֱ��tale of two charismatic species cooperating for mutual benefit has captivated naturalists for centuries – but evidence has been patchy. Researchers have now carried out the first large-scale search for evidence.

Scientists crack egg forging evolutionary puzzle

ta385 — Tue, 12 Apr 2022 06:00:00 +0000

A genetic study of Zambian cuckoo finches has solved one of nature’s biggest criminal cases, an egg forgery scandal two million years in the making. Its findings suggest that the victims of this fraud may now be gaining the upper hand.

Cheating birds mimic host nestlings to deceive foster parents

jg533 — Fri, 02 Oct 2020 13:23:30 +0000

Working in the savannahs of Zambia, a team of international researchers collected images, sounds and videos over four years to reveal a striking and highly specialised form of mimicry. They focused on a group of finches occurring across much of Africa called the indigobirds and whydahs, of the genus Vidua.

Like cuckoos, the 19 different species within this group of finches forego their parental duties and instead lay their eggs in the nests of other birds. Each species of indigobird and whydah chooses to lay its eggs in the nests of a particular species of grassfinch. Their hosts then incubate the foreign eggs, and feed the young alongside their own when they hatch.

Grassfinches are unusual in having brightly coloured and distinctively patterned nestlings, and nestlings of different grassfinch species have their own unique appearance, begging calls and begging movements. Vidua finches are extremely specialised parasites, with each species mostly exploiting a single host species.

Nestlings of these ‘brood-parasitic’ Vidua finches were found to mimic the appearance, sounds and movements of their grassfinch host’s chicks, right down to the same elaborately colourful patterns on the inside of their mouths. ̽��ֱ��study is published in the journal Evolution.

“ ̽��ֱ��mimicry is astounding in its intricacy and is highly species-specific,” said Dr Gabriel Jamie, lead author on the paper and a research scientist in the ̽��ֱ�� of Cambridge’s Department of Zoology, and at the FitzPatrick Institute of African Ornithology, ̽��ֱ�� of Cape Town.

He added: “We were able to test for mimicry using statistical models that approximate the vision of birds. Birds process colour and pattern differently to humans so it is important to analyse the mimicry from their perspective rather than just relying on human assessments.”

While the mimicry is very precise, the researchers did find some minor imperfections. These may exist due to insufficient time for more precise mimicry to evolve, or because current levels of mimicry are already good enough to fool the host parents. ̽��ֱ��researchers think that some imperfections might actually be enhanced versions of the hosts’ signal, forcing it to feed the parasite chick even more than it would its own.

̽��ֱ��mimetic adaptations to different hosts identified in the study may also be critical in the formation of new species, and in preventing species collapse through hybridisation.

“ ̽��ֱ��mimicry is not only amazing in its own right but may also have important implications for how new species of parasitic finches evolve,” added Professor Claire Spottiswoode, an author of the paper and a research scientist at both the ̽��ֱ�� of Cambridge and Cape Town.

Vidua nestlings imprint on their hosts, altering their mating and host preferences based on early life experiences. These preferences strongly influence the host environment in which their offspring grow up, and therefore the evolutionary selection pressures they experience from foster parents. When maintained over multiple generations, these selection pressures generate the astounding host-specific mimetic adaptations observed in the study.

Reference
Jamie, G. A, et al: ‘Multimodal mimicry of hosts in a radiation of parasitic finches.’ Evolution, July 2020. DOI:10.1111/evo.14057

̽��ֱ��common cuckoo is known for its deceitful nesting behaviour – by laying eggs in the nests of other bird species, it fools host parents into rearing cuckoo chicks alongside their own. While cuckoos mimic their host’s eggs, new research has revealed that a group of parasitic finch species in Africa have evolved to mimic their host’s chicks - and with astonishing accuracy.

̽��ֱ��mimicry is astounding in its intricacy and is highly species-specific.

Gabriel Jamie

Cheating birds mimic host nestlings to deceive foster parents

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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How humans and wild birds collaborate to get precious resources of honey and wax

amb206 — Fri, 22 Jul 2016 08:17:43 +0000

Humans have trained a range of species to help them find food: examples are dogs, falcons and cormorants. These animals are domesticated or taught to cooperate by their owners. Human-animal collaboration in the wild is much rarer. But it has long been known that, in many parts of Africa, people and a species of wax-eating bird called the greater honeyguide work together to find wild bees’ nests which provide a valuable resource to them both.

Honeyguides give a special call to attract people’s attention, then fly from tree to tree to indicate the direction of a bees’ nest. We humans are useful collaborators to honeyguides because of our ability to subdue stinging bees with smoke and chop open their nest, providing wax for the honeyguide and honey for ourselves.

Experiments carried out in the Mozambican bush now show that this unique human-animal relationship has an extra dimension: not only do honeyguides use calls to solicit human partners, but humans use specialised calls to recruit birds’ assistance. Research in the Niassa National Reserve reveals that by using specialised calls to communicate and cooperate with each other, people and wild birds can significantly increase their chances of locating vital sources of calorie-laden food.

In a paper (Reciprocal signaling in honeyguide-human mutualism) published in Science today (22 July 2016), evolutionary biologist Dr Claire Spottiswoode ( ̽��ֱ�� of Cambridge and ̽��ֱ�� of Cape Town) and co-authors (conservationists Keith Begg and Dr Colleen Begg of the Niassa Carnivore Project) reveal that honeyguides are able to respond adaptively to specialised signals given by people seeking their collaboration, resulting in two-way communication between humans and wild birds.

This reciprocal relationship plays out in the wild and occurs without any conventional kind of ‘training’ or coercion. “What’s remarkable about the honeyguide-human relationship is that it involves free-living wild animals whose interactions with humans have probably evolved through natural selection, probably over the course of hundreds of thousands of years,” says Spottiswoode, a specialist in bird behavioural ecology in Africa.

“Thanks to the work in Kenya of Hussein Isack, who electrified me as an 11-year-old when I heard him speak in Cape Town, we’ve long known that people can increase their rate of finding bees’ nests by collaborating with honeyguides, sometimes following them for over a kilometre. Keith and Colleen Begg, who do wonderful conservation work in northern Mozambique, alerted me to the Yao people’s traditional practice of using a distinctive call which they believe helps them to recruit honeyguides. This was instantly intriguing – could these calls really be a mode of communication between humans and a wild animal?”

With the help of honey-hunters from the local Yao community, Spottiswoode carried out controlled experiments in Mozambique’s Niassa National Reserve to test whether the birds were able to distinguish the call from other human sounds, and so to respond to it appropriately. ̽��ֱ��‘honey-hunting call’ made by honey-hunters, and passed from generation to generation, is a loud trill followed by a short grunt: ‘brrr-hm’.

To discover whether honeyguides associate ‘brrr-hm’ with a specific meaning , Spottiswoode made recordings of this call and two kinds of ‘control’ sounds : arbitrary words called out by the honey-hunters and the calls of another bird species. When these sounds were played back in the wild during experimental honey-hunting trips, birds were much more likely respond to the ‘brrr-hm’ call made to attract them than they were to either of the other sounds.

“ ̽��ֱ��traditional ‘brrr-hm’ call increased the probability of being guided by a honeyguide from 33% to 66%, and the overall probability of being shown a bees’ nest from 16% to 54% compared to the control sounds. In other words, the ‘brrr-hm’ call more than tripled the chances of a successful interaction, yielding honey for the humans and wax for the bird,” says Spottiswoode.

“Intriguingly, people in other parts of Africa use very different sounds for the same purpose – for example, our colleague Brian Wood’s work has shown that Hadza honey-hunters in Tanzania make a melodious whistling sound to recruit honeyguides. We’d love to know whether honeyguides have learnt this language-like variation in human signals across Africa, allowing them to recognise good collaborators among the local people living alongside them.”

̽��ֱ��greater honeyguide is widely found in sub-Saharan Africa, where its unassuming brown plumage belies its complex interactions with other species. Its interactions with humans to obtain food are mutually beneficial, but to obtain care for its young it is a brutal exploiter of other birds.

“Like a cuckoo, it lays its eggs in the nests of other birds, and its chick hatches equipped with sharp hooks at the tips of its beak. Only a few days old, the young honeyguide uses these built-in weapons to kill its foster siblings as soon as they hatch,” says Spottiswoode. “So the greater honeyguide is a master of deception and exploitation as well as cooperation – a proper Jekyll and Hyde of the bird world.”

Human cooperation is crucial to honeyguides because bees’ nests are often hidden in inaccessible crevices high up in trees – and honeybees sting ferociously. Therefore the honeyguide waits while an expert human undertakes the dangerous tasks of subduing the bees (by smoking them out using a flaming bundle of twigs and leaves hoisted high into the tree) and extracting the honey from within, usually by felling the entire tree. There is no competition for the prize: the honey-hunters harvest the honey and honeyguides devour the wax combs left behind.

Co-author Dr Colleen Begg adds: “ ̽��ֱ��Niassa National Reserve is as much about people as it is about wildlife, and this is really exemplified by these human-honeyguide interactions that have been forged over thousands of years of coexistence. While many people consider wilderness not to have people in it, at Niassa people are an essential part of the landscape.”

This foraging partnership was recorded in print as early as 1588, when a Portuguese missionary in what is now Mozambique observed a small brown bird slipping into his church to nibble his wax candles. He described how this bird had another remarkable habit: it led men to bees’ nests by calling and flying from tree to tree. Once the nest was located, he wrote in his account of life on the eastern African coast in the 17^th century, Ethiopia Oriental, the men harvested the honey and the bird fed on the wax.

“What João dos Santos described was what we now call a mutualism between species. Mutualisms are crucial everywhere in nature, but to our knowledge, the only comparable foraging partnership between wild animals and our own species involves free-living dolphins who chase schools of mullet into fishermen’s nets and in so doing manage to catch more for themselves. It would be fascinating to know whether dolphins respond to special calls made by fishermen, as Pliny the Elder asserted nearly two thousand years ago,” says Spottiswoode.

“Back in Africa, we’re fascinated by the evolution of the honeyguide-human mutualism and, as a next step, we want to test whether young honeyguides learn to recognise local human signals, creating a mosaic of honeyguide cultural variation that reflects that of their human partners. Sadly, the mutualism has already vanished from many parts of Africa. ̽��ֱ��world is a richer place for wildernesses like Niassa where this astonishing example of human-animal cooperation still thrives.”

̽��ֱ��project was funded by the Biotechnology and Biological Sciences Research Council (BBSRC) in the UK and the DST-NRF Centre of Excellence at the FitzPatrick Institute in South Africa.

For further information on this and other projects go to www.africancuckoos.com and www.niassalion.org

Inset images: Yao honey-hunter Orlando Yassene harvests honeycombs from a wild bees’ nest in the Niassa National Reserve, Mozambique (Claire Spottiswoode); Yao honey-hunter Orlando Yassene holds a female greater honeyguide temporarily captured for research in the Niassa National Reserve, Mozambique (Claire Spottiswoode); Yao honey-hunter Orlando Yassene chops open a bees’ nest in a felled tree in the Niassa National Reserve, Mozambique (Claire Spottiswoode); Yao honey-hunter Orlando Yassene holds a wax comb (honeyguide food) from a wild bees’ nest harvested in the Niassa National Reserve, Mozambique (Claire Spottiswoode); Claire Spottiswoode interviewing honey-hunter Issufo "Kambunga" Jaime (Mbumba Marufo).

By following honeyguides, a species of bird, people in Africa are able to locate bees’ nests to harvest honey. Research now reveals that humans use special calls to solicit the help of honeyguides and that honeyguides actively recruit appropriate human partners. This relationship is a rare example of cooperation between humans and free-living animals.

What’s remarkable about the honeyguide-human relationship is that it involves free-living wild animals whose interactions with humans have probably evolved through natural selection, probably over the course of hundreds of thousands of years.

Claire Spottiswoode

How honeyguide birds talk to people

Claire Spottiswoode

Yao honey-hunter Orlando Yassene holds a male greater honeyguide temporarily captured for research in the Niassa National Reserve, Mozambique.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Opinion: There’s a reason why Africa’s migratory songbirds sing out of season

Anonymous — Mon, 09 May 2016 11:15:42 +0000

Bird song has fascinated scientists for decades. Songs can be intricate, loud and, as it turns out, very important for reproductive success. In many species the males with the most complex songs secure the highest quality breeding territories and mates, and end up producing the most young. For species that spend their summers in Europe, almost every hour of daylight is crammed full with energetic and often very loud song.

For songbirds that have migrated to Africa at the end of the breeding season, singing shouldn’t be on their to-do list. Singing requires a big energetic investment and increases vulnerability to predators. ̽��ֱ��only time males should be willing to pay these costs is when there is a good chance of attracting females as mates, and that is not going to happen in Africa outside of the breeding season.

Despite this, several species of migratory songbirds, from Wood Warblers to Nightingales, are known to sing a great deal in Africa. This prompted us to ask: what is the purpose of singing in Africa, when the breeding grounds are thousands of kilometres away? To answer this question, we focused on a drab-looking but raucous singer, the Great Reed Warbler. This species breeds in Europe and spends the northern winter in the wet grasslands and savannahs of sub-Saharan Africa.

Testing a long-held hypothesis

We began by testing a long-held hypothesis for the persistence of singing in Africa. Perhaps singing is being used as a means to defend individual winter-feeding territories. It might be acting as a “keep out” sign to other individuals encroaching on the territory holder’s space.

In territorial systems, distinct boundaries are expected between the spaces used by each individual in combination with an aggressive reaction when that territorial boundary is breached. We used radio transmitters to track bird movements through the tall grasses of the study site in Zambia, and used models of Great Reed Warblers with recorded song to simulate territory intrusions. We found no support for the expectations of territoriality. Great Reed Warblers overlapped widely in their use of space, and individuals were unperturbed by other birds in their space.

Radio transmitters were used to track bird movements Jason Boyce

Given that Great Reed Warblers did not have a territorial system, this long-held hypothesis of singing for territorial protection didn’t hold up.

Singing for song improvement

Next, we tackled an intriguing but yet untested hypothesis. Perhaps, given the importance of song quality for males during breeding, they were using their downtime in Africa to improve the quality of their songs.

To find out, we combed through the literature and spoke to other researchers in Africa to determine which of the 57 migratory songbird species that migrate from Europe sing while in Africa and, importantly, how much. If this hypothesis is true, the benefits of singing in Africa should be most important for species in which song is especially valued when choosing a mate. Those should be species with the most complex songs, but conversely with the dullest appearance. So, when males are drab, females are expected to pay more attention to flashy song rather than flashy plumage.

Sure enough, we found that species with more complex songs, and those with drab plumage colouration, sing most often when in Africa. We argue that the costs associated with practice are probably well worth the investment for those species that stand to benefit most from producing the highest-quality songs.

A final piece of evidence comes from the Great Reed Warblers themselves. If songs function to defend territories, then they should sing the short territorial warnings they use to defend their breeding territories. But instead, recordings from Zambia showed that African songs are much more like those sung during mate attraction on the breeding grounds, when attracting a female is paramount. But there are a couple of important differences.

In Africa, songs are much longer and with many more switches between syllables than those sung in Europe. Given that songs in Africa are sung without a female receiver in mind, this may be the best way to practice. In Europe, when songs are mixed amongst the racket from competing males, repeating complex syllables up to five times is important to ensure that they are received loud and clear by females.

With the evidence tallied, both from Great Reed Warblers and across the dozens of songbird species that migrate between Africa and Europe, this puzzling non-breeding singing behaviour appears best explained as a rehearsal period before the big show the following spring.

To conclusively test this hypothesis, researchers would need to follow individual birds between their breeding and non-breeding grounds and monitor changes to their song and their breeding success. But this is close to impossible given the current tracking devices available. For now, this study points towards an intriguing new explanation for this previously unstudied behaviour. It also offers insight into the lives of migratory songbirds during the lengthy, but little-known part of their lives spent in Africa.

Marjorie Sorensen, Humboldt Postdoctoral Fellow, Goethe ̽��ֱ�� Frankfurt am Main and Claire Spottiswoode, BBSRC David Phillips Research Fellow and Hans Gadow Lecturer, ̽��ֱ�� of Cambridge

This article was originally published on ̽��ֱ��Conversation. Read the original article.

̽��ֱ��opinions expressed in this article are those of the individual author(s) and do not represent the views of the ̽��ֱ�� of Cambridge.

Claire Spottiswoode (Department of Zoology) and Marjorie Sorensen (Goethe ̽��ֱ�� Frankfurt am Main) discuss why several species of migratory songbirds sing a great deal in Africa when their breeding grounds are thousands of kilometres away.

Son of Groucho

̽��ֱ��African Golden Weaver, Zanzibar

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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Attribution

Natural born killers

gm349 — Wed, 07 Sep 2011 09:43:42 +0000

Only a few days old and still blind and naked, chicks of the African greater honeyguide kill their newly hatched foster siblings in order to eliminate competition for parental care, new research from the ̽��ֱ�� of Cambridge has found.

Honeyguides are brood parasites, cheats of the bird world that exploit the parental care of other birds to raise their young. Cuckoos are well-known examples, but parasitic behaviour has separately evolved in several other groups of birds too.

Honeyguides are celebrated for their unique cooperation with humans, whereby they guide honey-hunters to bees' nests and exploit the humans’ use of fire and tools to gain access to their favourite food, energy-rich bees' wax. But new research from Cambridge, published today (07 September 2011) in the Royal Society journal Biology Letters, has confirmed that honeyguides have a much darker side as unusually brutal brood parasites.

Honeyguides hatch from the egg already equipped with a pair of needle-sharp hooks at the tips of their beaks. It has long been inferred that they use these to kill the chicks of their hosts (often bee-eater birds) since maimed host young had been found alongside honeyguide chicks, but this behaviour had never been observed under natural conditions in host nests.

"This was very intriguing, so we buried infra-red video cameras within the hosts' underground nests to see what happened," said Claire Spottiswoode, the lead author of the paper. "While the apparent violence with which young honeyguides attacked their newly hatched foster siblings was quite shocking at first sight, it shows the power of evolution to shape amazing adaptations in parasites."

̽��ֱ��scientists have provided graphic video evidence of the honeyguide chicks’ behaviour, showing how they repeatedly grasp, bite and shake chicks of their host family until they eventually die. This behaviour occurs in pitch darkness because the most common hosts at the authors' Zambian study site, little bee-eater birds, nest in underground tunnels, usually dug into the roofs of abandoned Aardvark burrows.

" ̽��ֱ��killing behaviour is actually the culmination of a sequence of specialised adaptations that ensure that the young honeyguide has sole access to the food the host parents bring to the nest," said Dr Spottiswoode. " ̽��ֱ��honeyguide mother ensures her chick hatches first by internally incubating the egg for an extra day before laying it, so it has a head start in development compared to the host, and she also punctures host eggs when she lays her own. But some host eggs are overlooked or survive puncturing, and it is these eggs that precipitate chick killing by the young honeyguide has soon as they hatch."

Because the honeyguide hatches first, it has grown to about three times the weight of a hatchling bee-eater by the time it sets about killing it. ̽��ֱ��research showed that just one to five minutes of active biting time was enough to inflict sufficient injuries to cause host death. However, after maimed chicks stopped moving honeyguides often ceased their attacks and, as a result, hosts sometimes took over seven hours to die.

Host parents are apparently blithely unaware of what is happening and, in the darkness of their burrows, even attempted to feed a honeyguide chick busy attacking their own young. ̽��ֱ��researchers also filmed one instance of the honeyguide biting its foster parent by accident. By the time the honeyguide emerges from the burrow after about a month of assiduous care by its foster parents, however, its bill hook has grown out and there is no trace of its siblicidal beginnings.

"This behaviour is exactly analogous to that of young cuckoos, which hoist host eggs or chicks onto their backs and tip them over the rim of the nest. But because honeyguide hosts breed in tree holes or underground burrows, honeyguides can't eject host chicks and have instead evolved this highly effective killing behaviour to make sure that they alone monopolise the nest. Each time brood parasitism has evolved we see specialised adaptations for parasitic exploitation, which are no less astonishing for being sometimes rather gruesome."

This research was funded by ̽��ֱ��Royal Society and the DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, ̽��ֱ�� of Cape Town.

Newly hatched chicks of African honeyguide birds bite to death their foster siblings to eliminate competition.

̽��ֱ��killing behaviour is actually the culmination of a sequence of specialised adaptations that ensure that the young honeyguide has sole access to the food the host parents bring to the nest.

Claire Spottiswoode, the lead author of the paper

Claire Spottiswoode

African greater honeyguide

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Biological arms races in birds

gm349 — Wed, 13 Apr 2011 09:56:24 +0000

Brood parasitic birds such as cuckoos lay eggs that mimic those of their hosts in an effort to trick them into accepting the alien egg and raising the cuckoo chick as one of their own.

New research from the ̽��ֱ�� of Cambridge has found that different bird species parasitised by the African cuckoo finch have evolved different advanced strategies to fight back.

One strategy is for every host female to lay a different type of egg, with egg colour and pattern varying greatly among nests. These egg 'signatures' make it harder for the cuckoo finch to lay accurate forgeries. Since the female cuckoo finch always lays the same type of egg throughout her lifetime, she cannot change the look of her egg to match those of different host individuals - thus her chances of laying a matching egg are exasperatingly small.

Dr Claire Spottiswoode, a Royal Society Dorothy Hodgkin Research Fellow from the ̽��ֱ�� of Cambridge’s Department of Zoology, said: “As the cuckoo finch has become more proficient at tricking its hosts with better mimicry, hosts have evolved more and more sophisticated ways to fight back. Our field experiments in Zambia show that this biological arms race has escalated in strikingly different ways in different species. Some host species – such as the tawny-flanked prinia – have evolved defences by shifting their own egg appearance away from that of their parasite. And we see evidence of this in the evolution of an amazing diversity of prinia egg colours and patterns.

“These variations seem to act like the complicated markings on a banknote: complex colours and patterns act to make host eggs more difficult to forge by the parasite, just as watermarks act to make banknotes more difficult to forge by counterfeiters.”

̽��ֱ��researchers also found that some cuckoo finch hosts use an alternative strategy: red-faced cisticolas lay only moderately variable eggs but are instead extremely discriminating in deciding whether an egg is their one of their own. Thanks to their excellent discrimination, these hosts can spot even a sophisticated mimic.

Dr Martin Stevens, a BBSRC David Phillips Research Fellow from the ̽��ֱ�� of Cambridge’s Department of Zoology, commented on this aspect of the findings: “Our experiments have shown that these different strategies are equally successful as defences against the cuckoo finch. Moreover, one species that has done a bit of both – the rattling cisticola – appears to have beaten the cuckoo finch with this dual strategy, since it is no longer parasitised. ̽��ֱ��arms race between the cuckoo finch and its host emphasises how interactions between species can be remarkably sophisticated especially in tropical regions such as Africa, giving us beautiful examples of evolution and adaptation.”

Their findings are reported today in the journal Proceedings of the Royal Society B.

New research reveals how biological arms races between cuckoos and host birds can escalate into a competition between the host evolving new, unique egg patterns (or ‘signatures’) and the parasite new forgeries.

As the cuckoo finch has become more proficient at tricking its hosts with better mimicry, hosts have evolved more and more sophisticated ways to fight back.

Dr Claire Spottiswoode, a Royal Society Dorothy Hodgkin Research Fellow from the ̽��ֱ�� of Cambridge’s Department of Zoology

Claire Spottiswoode

Image shows a variety of cuckoo finches each adapted to mimic a different host species or colour morph

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