Can Parrots That Speak Different Dialects Understand Each Other?
by GrrlScientist  /  Oct 31, 2020

“Captive-bred parrots may develop a different dialect from their wild relatives and this could prevent them from being able to communicate effectively with their wild peers after they’re released. Puerto Rico’s endangered parrots may be facing a new challenge to their long-term survival: dialects. Conservation efforts have apparently allowed these iconic parrots to develop different dialects from their wild relatives. This may prevent them from being able to communicate effectively with their wild peers after they’re released into their native habitat, which could prevent them from finding mates, thereby threatening their survival.

Captive-breeding is a conservation strategy that is commonly used when endangered animal populations have plunged to a mere handful of individuals. On one hand, it can help wild populations recover their numbers after they’ve experienced dramatic declines, but on the other hand, it can create a variety of new problems that can also threaten endangered animals. One particularly powerful, yet rarely appreciated challenge is the cultural and behavioral differences that arise in captive-bred animals: these differences can severely limit the success of reintroduction of captive-bred animals into the wild because the environments they were raised in are often dramatically different from their wild homes, and because they lack opportunities to interact with and learn from their wild counterparts. This is the situation with the critically endangered Puerto Rican Amazon parrot, Amazona vittata. This hand-sized green parrot with a brilliant red forehead and dazzling blue flight feathers is often referred to as the iguaca, in respect for the onomatopoeic name inspired by the parrots’ flight call that the indigenous Taíno people knew it by.

Iguaca were not always rare: it’s estimated that more than one million of these parrots lived on Puerto Rico and its nearby islands in the early 1500s, when European colonizers first arrived. But we all know how the familiar old story goes: rampant destruction of old-growth forests ensued, destroying the parrots’ homes, food sources and precious nest cavities, which led to their fragmentation into several tiny, isolated populations. Combined with hunting and poaching for the international pet trade, the parrots’ numbers were reduced to just 13 individuals by 1975, making the iguaca one the ten most endangered bird species in the world, according to the U.S. Fish and Wildlife Service. Alarmed, conservation biologists designed a captive breeding plan to save these parrots before they slipped away forever. “The captive-breeding program began in 1973”, said conservation biologist Tanya Martínez, Project Leader for the Puerto Rican Parrot Recovery Project that is run by the Puerto Rico Department of Natural and Environmental Resources, in email. “At this point, they began bringing birds into captivity mostly by removing eggs and chicks from the few remaining wild nests.

But they didn’t successfully breed their first chick in captivity until 1979.” Despite this slow start, by 2006, there were 600 iguaca in four separate populations: a captive flock and a free-roaming reintroduced flock in Río Abajo State Forest, a captive flock established in 1973 in El Yunque National Forest, and the last members of the original wild flock that were confined to one of the island’s few remaining rainforests, El Yunque. Shortly after she started working with the iguaca, Ms Martínez noticed something strange about the different parrot flocks: they all spoke different languages. “I would say I first noticed about a year after I had been working with the parrots”, Ms Martínez said in email. It was 2013, and she was deciding on a topic for her MS project at the University of Puerto Rico, Mayaguez, when she first became aware of the acoustic differences between the wild and captive birds in the Río Abajo Forest.

“I noticed that I could usually tell if a wild or a captive bird was calling even if I couldn’t see it”, Ms Martínez said. “At this point, I had not yet visited the wild parrots in El Yunque but many of my co-workers had, and they always remarked on how different the wild birds in El Yunque sounded in comparison to all the other populations.” In fact, Ms Martínez soon found that all three captive-bred populations, which sounded different from each other, all sounded dramatically different from the last remaining truly wild flock, too. “If you would go into the El Yunque forest to work with the wild population, it almost sounded like a different species”, Ms Martínez pointed out in email. To better document these vocal differences, Ms Martínez recorded the calls produced by parrots in all four flocks (Figure 1) and used bioacoustic analysis software to analyze them. Because parrots have a large repertoire of sounds, Ms Martínez and her collaborators analysed variants of the two contact calls, which all of the parrots produce. They refer to these variants with the onomatopoeic names ‘caw’ and ‘chi’. Ms Martínez converted more than 800 hours of these recordings to spectrograms, which are pictures of sounds that show how auditory frequencies vary over time (Figure 2). Spectrograms are sometimes known as sonographs, voiceprints, or voicegrams. The spectrograms were then grouped based on their similarities to determine whether they could be accurately assigned to their source populations based on their acoustic structure. As Ms Martínez suspected, each of the four populations had its own discrete dialect.

Further, she found that contact calls produced by the relict flock at El Yunque were radically different from contact calls produced by all the other populations, and was described as a single repeated syllable, confirming anecdotal reports. It was almost as if the last truly wild flock was speaking a different language entirely. This contrasts with the contact calls produced by the other flocks of parrots, which are comprised of least two different syllables. Careful analysis revealed that the El Yunque captive, the Río Abajo captive and the Río Abajo free-flying populations all shared at least two call variants, but even still, each population’s contact calls were nevertheless distinctive. “The reasons why this happened vary between populations”, Ms Martínez said in email. “To start, the first captive population (the one in El Yunque) was founded by vocally naive parrots. The founders of the first captive population were brought into captivity as eggs and chicks and had not yet learned the wild dialect of their parents. These captive birds had few opportunities to interact with their wild counterparts because there were very few wild Puerto Rican Parrots left at this time and because the captive facility was not located very close to the few remaining wild parrot roosting and foraging sites”, Ms Martínez said in email. “Since they lacked vocal tutors of their own species, we believe that the first captive parrots may have modeled their vocalizations on Hispaniolan amazons.”

Hispaniolan amazon parrots, Amazona ventralis, are a closely-related species that is comparatively plentiful on their native Caribbean island of Hispaniola, which is split between the nations of Haiti and the Dominican Republic. These parrots were regularly used as foster parents for iguaca chicks in the early days of the conservation program to help boost the population numbers of iguaca and thus, large numbers of them were kept at the captive breeding facility for this purpose. “Vocal divergence occurred a second time when the second captive breeding facility was founded in Río Abajo”, Ms Martínez went on in email. Unlike the facility in El Yunque, this population was founded by adult birds so birds in the Río Abajo flock had the opportunity to learn their calls from members of their own species. “However, when populations are separated, cultural traits can undergo a process of cultural drift”, Ms Martínez said in email. Vocal learning, like any learning or copying process, is imperfect so innovations and tiny changes — “errors” — can emerge as one bird learns its calls from another. “This is one way in which dialects emerge in nature and we believe this is what happened in Río Abajo”, Ms Martínez explained in email. “A similar process likely explains the vocal divergence that occurred when parrots were released into the wild in Río Abajo. Cultural drift again causes the vocalizations to change. For the wild birds in Río Abajo, we believe that the vocal divergence was reinforced by the social interactions that occur outside of captivity. Wild birds model their vocalizations on other wild birds because these birds need to be able to communicate with each other to find food and mates.”

Parrots identify flock members on the basis of their vocalizations, and being a member of a flock comes with a number of other advantages besides finding mates, like evading predators, and working together to find ephemeral food sources. Tragically, the original dialect spoken by the last 50 or so remaining wild iguaca was forever lost when Hurricane Maria roared across Puerto Rico, destroying the last remnants of the precious relict population living in El Yunque. “Losing an entire wild population is an incredible blow to the recovery of any endangered species”, Ms Martínez explained in email. “But that wasn’t even the worst of it.” Not only did Hurricane Maria completely destroy the wild relict population in El Yunque, but it also caused a 40% decline in the free-flying iguaca population in Río Abajo. Hurricane Maria also caused significant damage to both breeding facilities in Río Abajo and El Yunque and damaged another facility in the Maricao Commonwealth Forest where a third captive population was being prepared for reintroduction by the Recovery Program. “We’ve been able to make a comeback in recent years though”, Ms Martínez added in email. “Today, the wild population in Río Abajo surpasses that of its pre-Maria numbers. A group of wild parrots was released in El Yunque at the beginning of 2020. The captive breeding facilities are being remodeled and there are plans to re-initiate the release efforts in Maricao Forest as early as next year.”

Are there any plans to teach the captive-bred iguaca their original calls? “Preserving the original calls at this point seems very unlikely”, Ms Martínez replied in email. “The relict dialect went extinct when hurricane Maria destroyed the relict population in El Yunque and there are no members of that population left that produce this dialect.” The original contact calls made by the relict flock of iguaca can only be heard in audio and video recordings. “However, the surviving dialects are still functional to the wild birds as evidenced by how well the wild flock in Río Abajo is doing”, Ms Martínez elaborated in email. “The calls are functional as long as all members of a given population respond to them within the appropriate contexts. That’s why it’s important to give captive birds every opportunity to listen and learn the wild calls of the population that they will be released into.” To ensure that the captive-bred parrots can understand the dialect spoken by the free-flying flocks of parrots that they will be joining, the Río Abajo breeding facility is situated so young parrots can hear the wild parrot flocks from the day they hatch.

Some wild parrots even nest close to the enclosures where captive-bred iguaca are preparing for their life of freedom. The breeding and foraging sites for free-flying iguaca at Río Abajo overlap with the breeding facility’s grounds. “Río Abajo has been a tremendous success. Its population has increased steadily over the years and this past breeding season we fledged a record 44 chicks in the wild.” Conservation is complicated and sometimes species management decisions that benefit a species in one way can have unintended consequences in the long term in ways that are difficult to predict. Although this is the first time that a dialect has been documented in any re-introduced animal population, I’ll bet it won’t be the last because we are now aware that this can happen and are looking for it. “Cultural behaviors (behaviors that one animal learns from another) can be especially tricky to manage in captivity because captivity usually implies removing an animal from the proximity of its wild counterparts and limiting access to its cultural tutors”, Ms Martínez agreed in email. “For conservation biologists, it can be especially important to pay attention to these types of behaviors.”

These findings have changed how conservationists are working with these parrots. First, they are working to blend the dialects of reintroduced birds and to familiarize them with other iguaca dialects. Second, they have stopped using Hispaniolan parrots as foster parents, and third, they have begun gradually reintroducing the birds into the wild, so they have time to watch, listen, and learn the dialect of the existing free-flying iguaca, who will serve as language tutors. Ongoing conservation efforts are beginning to pay off after the destruction caused by Hurricane Maria: Thirty captive-bred parrots were recently reintroduced into the wild iguaca’s last stronghold in the recovering El Yunque rainforest, where their calls — different but still functional — will once again fill the rainforest.”

Source: Tanya M. Martínez and David M. Logue (2020). Conservation practices and the formation of vocal dialects in the endangered Puerto Rican parrot, Amazona vittataAnimal Behaviour 166:261-271 | doi:10.1016/j.anbehav.2020.06.004

“Puerto Rican parrot Amazona vittata, known locally as the iguaca”

People’s Parrot Inspires Community-Sponsored Genome Project
by GrrlScientist / Feb 25, 2019

“An international team of 16 scientists recently published their conservation genomics study that had the primary goal of helping to prevent the extinction of three threatened parrot species. The project’s secondary goal was to demonstrate the applicability of conservation genomics for conserving endangered species. The researchers used cutting-edge technologies to sequence and assemble genome maps of the critically endangered Puerto Rican parrot, the Cuban parrot and the Hispanolian parrot, all of which (as their names suggest) are endemic to islands in the Caribbean Sea. These parrots are threatened by a variety of human activities, particularly logging and other forms of habitat destruction, the local pet trade, and growing pressures from expanding human populations occupying their island homes. Scientists have looked to islands as important model systems for research into speciation and extinction ever since Charles Darwin published his observations of those remarkable finches that he encountered on the Galapagos Islands roughly 150 years ago. Closer to home, Amazon parrots living on the islands of the Greater Antilles are another valuable model system for investigating how species disperse throughout an island archipelago and subsequently diversify.

But parrots are loud, colorful, intelligent and destructive, so they are the focus of human affection and persecution, which means these birds are often endangered. The Puerto Rican parrot is one of the ten most endangered bird species in the world, according to the U.S. Fish and Wildlife Service. But these parrots weren’t always vanishingly rare. When explorer and navigator, Christopher Columbus arrived on the island in 1493, more than one million Puerto Rican parrots were already there. At present, there are fewer than 500 wild and captive Puerto Rican parrots. “These parrots, especially the key species in the study, the Puerto Rican parrot, have very low genetic diversity because of a recent dramatic bottleneck (the population went down to 13 birds in the 1970s),” said evolutionary biologist and lead author of the study, Sofiia Kolchanova, in email. “The other species less so, but their numbers in the wild are decreasing and so does the diversity.”

Genetic diversity is important because it makes a species more resilient and adaptable so it can respond successfully to changes in the environment. Because the Puerto Rican parrot’s founder population comprised a mere handful of individuals, this raises some critically important questions about the conservation of these parrots: How much, if any, genetic diversity do they still possess? How does the Puerto Rican parrot’s overall genetic diversity compare to its closest relatives, whose populations are declining? What can we learn from studying the genomes of endangered species? To answer these questions, Taras Oleksyk, who studies genome diversity and its implications for evolutionary processes at Oakland University, and Walter Wolfsberger, a doctoral student in biological and biomedical sciences, teamed up with Ms. Kolchanova. Together with their other collaborators, they used advanced molecular biology and computational techniques to assemble a genome map of the Puerto Rican parrot, Amazona vittata, which is also known amongst the locals as the iguaca.

Sequences from the iguaca were then used as a reference for assembling and improving already existing genome sequences for the Cuban parrot, A. leucocephala, and the Hispaniolan parrot, A. ventralis. Because the iguaca had recently passed through a severe population bottleneck, the genomes of the remaining individuals are nearly identical, making the sequence data easier to work with. “Puerto Rican, Cuban and Hispaniolan parrots are sister species that populated the Caribbean islands at the same time, but since [then], each had a different demographic history. The Puerto Rican parrot has the lowest amounts of genetic diversity among the three,” Professor Oleksyk explained in email. “Due to the close relatedness of the three species, we can integrate information from them to annotate functional elements (like genes, etc) and to interrogate these sequences to learn about the evolutionary histories.” Together, these detailed genome maps were used to build models of the demographic history for these species, and were also interpreted within the larger context of parrot dispersals and evolution throughout the Caribbean (Figure 1).

Amazona parrots living in the Greater Antilles share the most recent common ancestor with the white-fronted amazon parrots, A. albifrons. These medium-sized, highly social parrots live in Central America and Mexico. Molecular evidence suggests they arrived twice in the Greater Antilles during the Pliocene Epoch (5.333 million to 2.58 million years before present): one wave of migrants apparently arrived first on Jamaica whilst the other wave probably arrived first on Cuba. After their arrival, the parrots then dispersed further, stepping stone-style, to colonize additional islands in the archipelago before finally arriving on Puerto Rico. Ms. Kolchanova, Professor Oleksyk and their collaborators then analyzed their detailed genome data to estimate the size of each species’ genome and to calculate their remaining levels of genetic diversity. What they found was deeply troubling. “As expected, these parrots do not have much genetic variation left,” Professor Oleksyk said. “This finding stresses the need for further conservation efforts.” The Puerto Rican parrot plays a pivotal role in the proper function of its island ecosystem, particularly for seed dispersal. “These parrots are the gardeners of the island, and as they’ve gone, the trees that have been cut down can’t come back,” Professor Oleksyk explained, noting that the relationship between the iguaca and the trees is one of interdependence. “The parrots can no longer [survive in large numbers] because the only place they can [breed] is inside tree hollows, and to have a tree hollow you need an old tree.”

This study also underscores the value of the new discipline of conservation genomics as an important tool for studying the dynamics of genetic diversity in populations over time. “[G]enomic data is useful in case of the wild populations […] for population status assessment, studies of population dynamics, and further fundamental research (e.g. evolution, comparative genomics etc) on these or other related species,” Ms. Kolchanova explained in email. “This project is part of an international effort to preserve these species and learn as much as we can about their biology and evolution,” Ms. Kolchanova added in email. “It is great that there are people who’re passionate about such things.” Genome sequencing got its start with the Human Genome Project, but today, scientists hope to sequence and study the complete genomes of every living species on Earth. What we learn about one species, such as the iguaca, can be applied to many other organisms. “Evolution of genomes is an ongoing story that unites all the living things,” Professor Oleksyk said in email. “[The] story of each species in written it its genome,” Professor Oleksyk elaborated. “Each nucleotide is there because it came through a long line of ancestry. Genome evolution is the story of how genetic diversity changes over time. This means both the ancient and the recent story. The ancient story is about natural history and phylogeny: where did this species come from, what is it related to, how different is it from other species, what really makes it so unique? The recent story is about conservation status and demography: how many individuals there are, how much variation has there been and how much is still left, what is the chance of this population’s survival and what we can do to help it? I moved to Puerto Rico from the National Cancer Institute in Maryland, as I wanted to look for interesting questions,” Professor Oleksyk explained in email. “There I met with people at the Puerto Rican parrot recovery program, and I wanted to help.”

This conservation genetics project was hatched at the convergence of a unique set of circumstances. First, funding challenges faced by the researchers forced them to “think outside of the box”. Professor Oleksyk, who often championed the iguaca as “the people’s parrot”, used a variety of clever methods to inspire Puerto Ricans from all walks of life to crowd-fund this project to help conserve their island’s mascot. “In 2010, this genome would have cost us close to $100K. Asking for that much money would take a long time, and the funding for science seemed to be decreasing,” Professor Oleksyk said. “However, early in 2011 we noticed how quickly the prices were falling. When the projected price went down to $10,000 we decided not to go the conventional route of submitting grants and [instead] try to raise money on our own.” Almost overnight, what once had been nearly impossible had suddenly become feasible. “We convinced our community that they could contribute to the development of local science, and our science can contribute to better understanding of the island’s beloved species that needs help to come back from the brink of extinction.”

Once they got started, the project was surprisingly achievable: For example, the Puerto Rican parrot’s genome was relatively small (1.65Gb), it was readily available from the USFWS captive breeding program, and the complicated process of assembly and annotation of the sequence data were conducted as part of an undergraduate biosciences education and training program at the University of Puerto Rico at Mayagüez. “Today’s science is always a large collaborative effort,” Professor Oleksyk elaborated in email. “Very few projects in genomics can be done by a single person, research requires many specific skills. Many people do many different parts: someone, usually a veterinarian or aviculturist identifies and collects the right samples, someone has to get the DNA and RNA transported and extracted at the genome quality level, and once you work with bioinformatics tools, there are experts on genome assembly, phylogenetics, annotation, demographics. Once you are collaborating all of these efforts, you have to go back to all these experts and make sure that every part of the analysis holds together, and every experiment is described in excruciating detail, so it can be replicated [by others].”

But what was the most inspiring aspect of this collaborative effort? “I think one of the most important things here is that in the process we involved many young researchers in the creative process of building a project from ground up,” Professor Oleksyk said. “We had artists, scientists, fashion designers, community activists — all galvanized by a parrot genome project.” And who knows: Ms. Kolchanova’s and Professor Oleksyk’s determination and willingness to try novel approaches to make this project happen may provide an important — and inspirational — model for how to accomplish future genome research.”

Source: Sofiia Kolchanova, Sergei Kliver, Aleksei Komissarov, Pavel Dobrinin, Gaik Tamazian, Kirill Grigorev, Walter W. Wolfsberger, Audrey J. Majeske, Jafet Velez-Valentin, Ricardo Valentin de la Rosa, Joanne R. Paul-Murphy, David Sanchez-Migallon Guzman, Michael H. Court, Juan L. Rodriguez-Flores, Juan Carlos Martínez-Cruzado and Taras K. Oleksyk (2019). Genomes of Three Closely Related Caribbean Amazons Provide Insight for Species History and Conservation, Genes, 10:54–71 | doi:10.3390/genes10010054



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