Animal world: How to make your announcements heard
What audible components of animal communication serve an alerting function?
University of Konstanz
It is hard to be attentive to all the information that is around us; we need to focus on particular signals or sensory channels to get more details. This is why alerting signals are frequently used in human communication: for example, calling “hey” before addressing another person or sounding a chime before announcements at train stations and airports.
We can find these alerting components among animals as well – signals whose primary function is to draw conspecifics’ attention to what they are about to communicate. “As an animal, this is even more crucial because you always need to monitor your environment. Otherwise, you’ll miss food opportunities or fail to notice predators”, says behavioural ecologist Vlad Demartsev. This is why alerting signals make communication more efficient – for the receivers, as continuous focused attention on one, specific signal reduces their capacity to monitor their environment. And for the signallers, the alerting signals ensure that the core message, which may be costly or risky to produce, is received.
Vlad Demartsev, a post-doc at the Cluster of Excellence “Collective Behaviour” at the University of Konstanz and the Max Planck Institute of Animal Behavior, and his colleagues from Tel Aviv University and Bar-Ilan University introduce a framework to test animal signals for their alerting function in a paper recently published in the journal Animal Behaviour. In a second step, they applied this framework to find out whether the introductory notes (“wails”) in rock hyraxes’ songs met the criteria for such an alerting function.
Clues to an alerting function
The proposed framework is based on examining three tiers: the signal itself, the signaller and the audience. To begin with, an alerting signal is expected to be heard from greater distances and resist being drowned out by environmental noise. Do signallers use the component flexibly – e.g. omit it if receivers react to it, or repeat it in case of environmental noise? And on the listening side, does the signal affect the receivers in a predictable way, increasing the likelihood and speed of their responses? “The phenomenon of alerting signals is likely widespread among animals”, says Demartsev, “but so far, we haven’t had a systematic method to examine it.”
Rock hyraxes are social mammals with a well-described vocal repertoire. Their songs are complex with much information encoded in them, and as singing mammals, they are quite unique. Male hyraxes may use the songs to advertise themselves to potential female mating partners and assess competitors. It is thus crucial for them to be heard, whereas the costs may be high, if they are detected by predators or aggressive rivals.
Rock hyrax songs are arranged in sequences of three distinct vocal elements. These include “wails” that Demartsev and his colleagues hypothesize might have an alerting function, as they are the opening elements in songs and frequently subside as songs progress. Moreover, wails are not correlated with the male animals’ traits like age or rank – unlike other vocal elements.
Hey, listen to me
The question is: How did the researchers assess whether wails potentially serve an alerting purpose? First of all, they analyzed all the song data they had collected and found out that wails are only used at the beginning of songs and are dropped if the songs are sung following events that already attract conspecific attention (such as predator presence, alarm calls or fights). Then the research team conducted experiments on the physical propagation and the degradation of those sounds over distances and under different wind conditions.
“Finally, we field experimented with rock hyrax songs. We took a template song, played it, measured the responses by other rock hyraxes, and then we deleted most of the wail elements and replaced them with background noise. We also segmented wails and broke the continuous structure of the songs. With both of these manipulations, we saw a reduction in the audience’s responses”, explains the biologist.
Wails meet several criteria for an alerting component: They are stable over medium transmission distances, they happen at the start of the song, and they are associated with an increase in the response rate, which the researchers describe as a crucial benchmark for alerting significance. “Wails likely serve as alerting signals, even though they don't meet all of our criteria perfectly. Some ecological constraints definitely have an effect, such as habitat structure, background noises, or risks from predation. Besides, I would not go as far as saying that alerting is the only function wails have. They might encode additional information that we haven’t found yet”, Demartsev explains.
The researchers hope their framework for assessing potential alerting signals will be applied to other species as well. Future research could also examine the evolutionary trade-offs associated with producing highly detectable signals, e.g. enhanced conspicuousness to unintended receivers such as predators or competitors.
Key Facts:
- The study “Alerting components in animal vocalisation” was recently published in the journal Animal Behaviour.
- The study introduces a framework to test animal signals for their alerting function and, in a second step, applies this framework to evaluate whether the introductory notes in rock hyraxes’ songs meet the criteria for an alerting function.
- Authors:
Behavioural ecologist Vlad Demartsev (first author) works as a post-doc at the Cluster of Excellence "Centre for the Advanced Study of Collective Behaviour" at the University of Konstanz and is an associated researcher at the Max Planck Institute of Animal Behavior.
Behavioural ecologist Eli Geffen (last author) is professor at the School of Zoology at Tel Aviv University (Tel Aviv, Israel).
Other contributors to the paper were Yair Geva, Pablo Alba González and Amiyaal Ilany (all from the School of Zoology at Tel Aviv University) and Lee Koren (Bar-Ilan University, Ramat Gan, Israel). - Funding: Israel Science Foundation, Alexander von Humboldt-Stiftung, German Research Foundation (DFG) funding for the Cluster of Excellence "Collective Behaviour" (EXC 2117 – 422037984)
Note to editors:
You can download images here:
Photo (DSCN 1947 and/or 2780): Subtitle: Rock hyrax at Ein Gedi Nature Reserve, Israel;
Copyright: Héloïse Brotier and Lee Koren, Bar-Ilan University
https://www.uni-konstanz.de/fileadmin/pi/fileserver/2025_extra/wie_tiere_sich_untereinander_1.JPG
https://www.uni-konstanz.de/fileadmin/pi/fileserver/2025_extra/wie_tiere_sich_untereinander_2.JPG
Video (Sing 3.mp4): Subtitle: Rock hyraxes’ songs are quite complex and begin with wails.
https://youtu.be/dG1MrRnPkMM?si=4nTwfuLxE992S-z8
Copyright: Héloïse Brotier and Lee Koren, Bar-Ilan University
Journal
Animal Behaviour
Wild giraffes lose their conservation safety net as zoo populations hybridize
image:
New genomic research shows widespread hybridization among North American giraffes in zoos and private ranches, diminishing their conservation value.
view moreCredit: Kari Morfeld, Morfeld Research & Conservation LLC.
URBANA, Ill. — Zoos and private collections teach, inspire, and connect people to animals they may never encounter in the wild. And, in some cases, those animals represent valuable ‘assurance populations’ — essentially, backups that could be used to revive critically endangered populations in their native ranges. But new research from the University of Illinois Urbana-Champaign and Morfeld Research & Conservation shows American giraffe collections have been hybridized across species, sharply reducing their conservation value.
“Captive breeding programs in zoos would be better off restarting with fresh stocks from the wild, if they want to maintain assurance stocks for the purposes of conservation,” said senior study author Alfred Roca, professor in the Department of Animal Sciences, part of the College of Agricultural, Consumer and Environmental Sciences at Illinois.
Wild giraffes can’t afford to lose their backups. With a population of approximately 97,500 across 21 African countries, the animals have long been listed as vulnerable on the International Union for Conservation of Nature’s Red List. For conservation to work, though, there must be a basic understanding of which species are where, and how they interact with other populations and their environment. These fundamental questions help conservation biologists manage the unique needs of the animals they protect.
For years, all giraffes were thought to be part of a single species, with nine subspecies scattered across the African continent. However, recent advancements in DNA sequencing indicate that giraffes actually fall into four distinct species that rarely intermingle, much less interbreed. Earlier this year, the IUCN formally recognized all four species as vulnerable, with several populations categorized as critically endangered.
Why does this matter for captive collections? As genetic repositories for wild populations, animals in human care should represent what’s in the wild. But, after analyzing the DNA of 52 giraffes across American facilities, including private ranches and zoos, Roca and his collaborators found the opposite: these animals have become a genetic mish-mash, reflecting decades of interbreeding and hybridization.
“We compared the DNA sequences of giraffes from North American collections to 63 wild individuals across all four species and were able to see how strongly their genetics aligned with different species in the wild,” said Wesley Au, the study’s first author and doctoral researcher in the informatics program at U. of I. “Only eight giraffes got close to representing a single species — reaching about a 90% match — but the rest were a mix of two and sometimes three species.”
Chris Fields, study co-author and lead of the HPCBio core in Illinois’ Roy J. Carver Biotechnology Center, added, “This study demonstrates how to perform conservation studies through genomics, by comparing genome data from the giraffes to reference genomes from wild species.”
The team determined that a handful of individuals may have originated from a wild reticulated giraffe that itself was a rare natural hybrid. According to the researchers, the others may have resulted from a 2004 Association of Zoos and Aquariums policy to manage most giraffe breeding as a single ‘generic’ unit, rather than maintaining separate breeding programs for individual subspecies, as the AZA had done previously.
“The AZA decision acknowledged that hybridization was already extensive within its giraffe population,” Roca said. “Additionally, I'm not sure it was obvious in 2004 that the animals were from such disparate genetic stocks. Those studies came later, so it's not surprising.”
Study co-author Kari Morfeld says captive breeding programs often prioritize animal demeanor.
“A lot of times, decisions to breed animals are based on, ‘She's a nice female, he's a nice male. Let's put them together for breeding.’ The genetics aren’t usually considered in making breeding decisions for giraffes, but they should be. We have a responsibility to consider genetics, not only demeanor or physical characteristics, to do better for giraffe conservation,” said Morfeld, reproductive physiologist and owner of Morfeld Research & Conservation.
The researchers recommend phasing out hybridized animals from the captive breeding program. These animals certainly have inherent value, especially as ambassadors for giraffes, and some could potentially serve as surrogates for implanted embryos representing wild genetics. Additionally, more animals could be screened to learn whether better genetic matches to wild populations already exist within the American giraffe collection.
Finally, the authors say giraffe conservation plans can’t hinge entirely on zoos and ranches — major investments are needed to restore wild populations in Africa, some of which have dwindled precipitously close to local extinction.
Morfeld acknowledges that starting the breeding program from scratch with wild genetics would be a logistical challenge.
“Physically moving these huge animals between continents would be difficult. So, a better way, in my opinion, is to develop reproductive technologies where you can move semen or embryos and proceed with artificial insemination, IVF, and embryo transfer. We do this all the time in livestock and other species. There's no reason this can't be applied to giraffes.
“And there are a lot of things to consider beyond moving genetics,” Morfeld added. “It really comes down to establishing trusting relationships with African governments, conservation organizations, and scientists. It's one thing to conduct an artificial insemination, but you really have to ask the question of how all stakeholders will benefit.”
The study, “Genomic assessment of giraffes in North American collections highlights conservation challenges,” is published in the Journal of Heredity [DOI: 10.1093/jhered/esaf089]. Authors include Wesley Au, Kari Morfeld, Christopher Fields, Yasuko Ishida, and Alfred Roca.
Research in the College of ACES is made possible in part by Hatch funding from USDA’s National Institute of Food and Agriculture. This study was also supported by Morfeld Research & Conservation, LLC, Daniel Houck II, and Missy Howell.
Roca is also affiliated with the Carl R. Woese Institute for Genomic Biology, the School of Information Sciences, and the Illinois Natural History Survey, part of the Prairie Research Institute at U. of I.
Journal
Journal of Heredity
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