|Winemiller honored by the American Fisheries Society
Posted: 31 Aug 2018 06:00 AM PDT
Media contact: Blair Fannin, 979-845-2259, firstname.lastname@example.org
COLLEGE STATION – Dr. Kirk Winemiller has received the American Fisheries Society Award of Excellence and was inducted as a Fellow at the society’s 2018 annual meeting in Atlantic City, New Jersey.
Dr. Kirk Winemiller, Texas A&M AgriLife Research scientist and Regents Professor in the department of wildlife and fisheries sciences at Texas A&M University, College Station, has received the Award of Excellence and was inducted as a Fellow of the American Fisheries Society. (Texas A&M AgriLife photo)
Winemiller is a Texas A&M AgriLife Research scientist and Regents Professor in the department of wildlife and fisheries sciences at Texas A&M University, College Station.
American Fisheries Society President Steve L. McMullin presented the award at the meeting’s plenary session.
The Award of Excellence is presented to a living person for original and outstanding contributions to fisheries and aquatic biology. It is the Society’s highest award for scientific achievement.
“We applaud the distinguished contributions of Dr. Winemiller and thank him for his continuous efforts to share the value of fisheries and aquatic biology,” McMullin said.
Winemiller’s research activities and interests focus on multiple areas, including ecology, evolution, systematics, biology, fisheries management, and biodiversity conservation. His publications in these fields have led to major advances in fisheries and aquatic ecosystem management.
Winemiller has published more than 250 peer-reviewed articles with his most cited papers concerning fish life history. Winemiller’s life-history model predicts how demographic tradeoffs influence fish population responses to environmental variation—particularly to altered flow regimes and harvest levels. He has also advanced the science of fish food-web ecology, fish functional traits and fish density dependence, according to the society.
Winemiller received the George Mercer Award in 1992 from the Ecological Society of America for an outstanding ecological research paper published by a researcher younger than 40 years old.
Winemiller has also been recognized as a Fellow of the American Association for the Advancement of Science, and a Fellow of the Ecological Society of America.
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There’s a new article by Dr. Jacquelyn K. Grace about maltreatment of wild birds and the effects of certain stressors. To read more about how early-life maltreatment stress responses of the wild birds, follow this link.
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Dr. Delbert M. Gatlinn III has an article in Aquaculture on the metabolic responses of Nile tilapia. Interested in learning more? Then, please click here to read the full article regarding the tilapia’s responses to methionine and taurine supplementation.
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Dr. Lee A. Fitzgerald has a new article in the Ecological Applications, Ecological Society of America on the Dispersal and population state of an endangered island lizard. If you would like to check out the article and learn more about the population and dispersal of the island lizards, please click here.
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Angeli, N. F., Lundgren, I. F., Pollock, C. G., Hillis-Starr, Z. M. and Fitzgerald, L. A. (2018), Dispersal and population state of an endangered island lizard following a conservation translocation. Ecol Appl. doi:10.1002/eap.1650
Download PDF: Who’s eating all the shrimp?
Whether in prawn cocktail, shrimp gumbo, or grilled on the barbeque, you’ve probably eaten shrimp lots of times. It’s the most common seafood in the US. An American eats on average 4 pounds of it every year!
While we know that shrimp is a popular seafood, we wanted to find out how important it was in supporting other valuable fish species in the Gulf of Mexico.
We studied the relationship between the abundance of shrimp and the fish that eat them, and found that there was a statistical link between the two. Although we cannot conclude that this is entirely due to the abundance of shrimp, we believe that our research shows that shrimp are a really important prey for these fish species.
Shrimp fishing is big business in the Gulf of Mexico! In fact, it’s the most valuable fishery in the entire Gulf region, contributing a whopping 65% of all US shrimp (Fig. 1). But that’s not the only reason why shrimp are valuable…
Recent studies have shown that shrimp might be a very important prey for larger fish. We call this type of species forage species, which means that if their population falls, it will have a negative impact on the populations of the fish that eat them (their predators).
Three of the major predators of young (juvenile) shrimp in the Gulf of Mexico are southern flounder, spotted seatrout and red drum. These fish are really important for recreational and/or commercial fisheries. The potential decrease in shrimp abundance is a big ecological concern because of its role as prey supporting many valuable predators, such as these fish species.
In this study, we wanted to find out how important shrimp were as a forage species for these fish.
From 1986 to 2014 the Texas Parks and Wildlife Department (TPWD) used different types of nets to collect samples of white shrimp and brown shrimp, and three fish species: southern flounder, spotted seatrout and red drum (Fig. 2). Juveniles and young adults of these fish prey upon shrimp, so these were the stages included in our statistical analysis.
While sampling took place monthly for shrimp, we found more brown shrimp in May and more white shrimp in August and November than during any other months. We used shrimp data from these months in the analysis and matched these data to the closest spring and fall catch data available for the fish.
We converted these data into an indicator known as catch-per-unit effort (CPUE), which in this case is the number of individuals of each species caught per hour within the nets used for sampling. It shows the relative abundance of each species in a particular place and time.
We investigated the statistical relationship between the CPUE of shrimp as prey and fish as predators over the time of the studies. We call these data a ‘time series’. We ran two types of statistical analysis on these time series to look for relationships between the abundance of shrimp and the abundance of fish.
The two statistical analyses we used were Partial Least Squares Regression (PLSR) and co-integration analysis. PLSR is good for finding links between two variables (shrimp and fish) in year-to-year fluctuation, while co-integration analysis is good for slowly changing (increasing or decreasing) time series, which are called “non-stationary time series.” Most of our CPUE time series were non-stationary.
Our PLSR analysis found 8 significant relationships between shrimp and fish time series out of a total of 36 comparisons.
Our co-integration analysis showed significant associations between 31 out of 70 shrimp and fish time series pairings.
Using co-integration analysis we also found that white shrimp in August and brown shrimp in May were strongly linked with fish CPUEs in bays on the southern coast of Texas (Fig. 3). White shrimp in November were more strongly linked with fish CPUEs in bays located to the north.
All three fish species appeared to be affected by shrimp abundance in all of the regions that we studied.
We predicted that if our two shrimp species were vital for the fish in our study, there would be a statistical association between the changes in abundance of prey and predator.
Our PLSR analysis wasn’t conclusive because we found associations between shrimp and fish CPUEs in only 22% of cases. These associations could have just been because of statistical error.
However, our co-integration analysis showed significant associations in 52% of cases. It also revealed clear patterns between the seasons and different locations.
Different shrimp species are important at different times of the year and in different parts of the Gulf of Mexico. Observed patterns in their abundance over the latitude (the distance from the equator) might be because of changes in temperature or salinity – both of which have an effect on shrimp populations. We would need to do further studies to better understand these effects.
Fishing for all of the species in this study has had a big impact on their populations, and affected their roles as prey or predators. There have been lots of improvements in fishery management practices to stop overfishing. It is possible that these actions could be covering up, or adding to, the statistical associations that we saw.
The importance of any fishery stock is normally worked out by its market value when caught. Our research shows that the ecological importance of shrimp has been underestimated. The shrimp are not just valuable as a fishing stock, but they are also important as a forage species for three of the most valuable fishes in the Gulf of Mexico.
Using statistical analyses we found that there was a significant relationship between shrimp abundance and the presence of these three fish species in the Gulf of Mexico.
We also found that naturally-occurring changes in shrimp abundance from year to year complicate this relationship and additional studies are needed. However, it’s clear that shrimp fisheries need to be regulated in order to keep them sustainable. If not, it could have a negative effect on these three valuable fish species.
Glossary of Key Terms
Commercial fisheries − The people and companies who catch fish to sell them.
Habitat − The place, or type of place, where an animal lives and hangs out.
Predator − An animal that’s above another in the food web. In our study, the predators were the southern flounder, spotted
seatrout and red drum.
Prey − An animal that’s below another in the food web. In our study, the prey were the white and brown shrimp.
Recreational fishing − People who catch fish for fun and/or for their own food.
Salinity − The salt content of the sea. High salinity means there’s a lot of salt, low salinity means that there is not as much.
Significant − A result that is likely not due to chance, but rather due to a real process. Scientists often define a result as
“significant” if it would happen by chance less than 5% of the time.
Check your understanding
- One of the changes in management practices was to reduce the sale of new shrimp fishing licenses and a buyback program for old licenses. Over 65% of shrimp fishing licenses were bought back and retired. What effect do you think this would have had on the shrimp population?
- Most young shrimp start their lives in marshes and coastal wetlands. Our findings show the importance of protecting ecological integrity of such habitats in order to increase the amount of shrimp reaching adulthood and helping the valuable fish species they support. What management strategies would you suggest to protect these habitats?
- Scientists have proven that temperature affects the survival and growth of shrimp in the Gulf of Mexico. Why do you think this is?
- Why is statistical analysis alone not sufficient to prove a relationship between the abundances of shrimp
and fish? What other data can help prove a relationship?
Мore free environmental science resources аt: www.ScienceJournalForKids.org
Fujiwara M, Zhou C, Acres C, Martinez-Andrade F (2016) Interaction between Penaeid Shrimp and Fish Populations in the Gulf of Mexico: Importance of Shrimp as Forage Species. PLoS One http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0166479
Alder J, Campbell B, Karpouzi V, Kaschner K, Pauly D. (2008) Forage fish: From ecosystems to markets. Annual Review of
Environment and Resources. http://www.annualreviews.org/doi/abs/10.1146/annurev.environ.33.020807.143204
EPA: About Coastal Wetlands: https://www.epa.gov/wetlands/coastal-wetlands
Publication supported in part by an Institutional Grant (NA14OAR4170102) to the Texas Sea Grant College Program from the National Sea Grant Office, National Oceanic and Atmospheric Administration, U.S. Department of Commerce. All views, opinions, findings, conclusions, and recommendations expressed in this material are those of the author(s) and do not necessarily reflect the opinions of the Texas Sea Grant College Program or the National Oceanic and Atmospheric Administration.
COLLEGE STATION – Dr. Kevin Conway is ecstatic.
Conway, a Texas A&M AgriLife Research wildlife and fisheries scientist at College Station, is part of a joint team of researchers from Texas A&M University and Texas Parks and Wildlife Department who after years of searching, recently collected a rare fish from the Rio Grande.
“The Rio Grande Shiner, Notropis jemezanus, is a type of freshwater cyprinid fish, commonly referred to as carps, minnows and shiners, that is endemic to the Rio Grande drainage,” Conway said. “It’s large as shiners go, growing up to about 3 inches in length, and though it has never been economically valuable from a commercial or recreational standpoint, it is certainly a valuable bioindicator of river health.”
Not unlike the now extinct passenger pigeon, which was once so numerous their flights could block the sun, Conway said the Rio Grande shiner was formerly found throughout almost the entire Rio Grande drainage and was one of the most abundant species in the system. But its numbers declined steadily in both Texas and New Mexico until it became a rarity.
“It’s not been collected in the Rio Grande in New Mexico since the 1940s and has only been collected sporadically from the lower Rio Grande along the Texas-Mexico border since 2000,” Conway said. “Its decline in Texas seems to have slipped under the radar and is likely the result of the interplay of anthropogenic manipulation of the system, including impoundment, dewatering and possibly the introduction of invasive species.”
Other contributing factors Conway alluded to were poor water quality stemming from agricultural and urban runoff and sewage effluent entering the river. Changing land management practices, including the loss of riparian gallery forests and floodplain habitats and water withdrawals, impact spring flood pulses, which serve as spawning cues for the fish, further adding to the fishes’ woes.
Those up on shiner politics might ask why some native species such as the Red Shiner are doing OK in the Rio Grande while others like the Rio Grande Shiner are not? Conway said the answer may stem from the reproductive nature of the Rio Grande Shiner.
“The Rio Grande Shiner belongs to a unique reproductive guild referred to as pelagic broadcast spawners,” he said. “Members of this guild shed eggs and sperm directly into the water column. Fertilization and development of the semi-buoyant eggs occur as they drift downstream. The eggs only take a couple of days to hatch, but in that time they can drift a long way and must remain suspended in the water column.”
Trouble comes when the streamflow slows or stops due to impoundments or too much water leaves the river during drought or times of heavy irrigation, Conway said. When the stream flow becomes too slow to move the eggs along, they sink to the bottom and become trapped in the substrate and die.
“Needless to say, these pelagic broadcast spawning shiners are among the most threatened species of freshwater fishes in the U.S., particularly in the Great Plains and desert regions of the Southwestern U.S., including Texaswhere streamflow can slow to a trickle,” Conway said. “Those like the Red Shiner continue to do well in the Rio Grande because they lay their eggs directly on the substrate where they hatch and don’t require a large stretch of river to drift in the water column.”
Conway has been conducting surveys for Rio Grande Shiner along the Texas-Mexico border since 2014 as part of a project funded by Texas Parks and Wildlife Department. Despite multiple attempts to find the fish, he had had no luck.
In a last-ditch effort in March, Conway joined forces with Megan Bean, a TPWD fish conservation biologist from Kerrville, to try to locate the species near Eagle Pass and Laredo where Bean was previously successful in finding the rare fish.
Bean said Conway’s AgriLife Research projects with the Rio Grande Shiner provide Texas Parks and Wildlife Department and conservation partners with important information on species distribution and status as well as river health. She said this information provides a data-driven, science-based approach to species conservation and management.
“We worked together to identify sites we thought would work based on earlier findings of researchers from Texas State University, University of Texas and the University of New Mexico and voucher specimens within museum collections,” Conway said.
The joint research team managed to collect four fish from the Rio Grande just downstream from Shelby Park in downtown Eagle Pass on March 21.
“This was the only spot out of six sampled by the joint agency team that produced specimens of this rare shiner,” Conway said. “But at least we are relieved to know they still exist.”
So why so much angst over a minnow?
“That’s a good question since there are lots of different silvery minnows around, so I guess you could look at this from two different points of view,” Conway said. “First, the Rio Grande shiner is probably the largest species of shiner in the U.S. and it would be a tragedy to lose it, not only because of its unique characteristics but also because there are very few pelagic broadcast spawning fishes in the U.S. in the first place. And second, the presence of a healthy number of pelagic broadcast spawners within a particular river system could be taken as a sign that the system is healthy. When they are gone then it could be taken as a sign the physical characteristics of a river have been significantly degraded. Once they are gone from a system it is not easy to put them back.”
Texas Pride is also no small reason for saving the shiner in Bean’s estimation.
“The Rio Grande Shiner is found nowhere else in the world except for this region in the U.S. and Mexico,” Bean said. “This small fish is a unique part of our natural resource heritage we should conserve, manage and treasure. It’s a part of what makes Texas so special.”
Though the future seems bleak for the Rio Grande Shiner in the lower part of the Rio Grande along the Texas-Mexico border, Conway said there may still be light at the tunnel’s end.
“We’re comparing the DNA of the four recently collected fish with that of individuals from the Pecos River in New Mexico to assess whether members of these two populations are genetically similar,” Conway said.
“The genetic investigation of the New Mexico and Texas samples of Rio Grande Shiner are being conducted by Dr. Megan Osborne at the University of New Mexico and Dr. Dave Portnoy at Texas A&M University-Corpus Christi. We are anxiously awaiting the results of these analyses in order to plan the next steps in the conservation of the Rio Grande Shiner in Texas.”
A set of curious researchers, state-of-the-art visual technology and a bit of good luck helped find a new fish whose tooth collection could put a shark to shame.
Scientists at the University of Washington, Texas A&M University and the Western Australian Museum have discovered and named a new genus and species of clingfish after stumbling upon a specimen preserved in a jar dating back to the 1970s. The fish was unmistakably different from the other 160 known clingfishes, named for the disc on their bellies that can summon massive sticking power in wet, slimy environments.
The researchers named the new species “duckbilled clingfish” (Nettorhamphos radula) for its broad, flat snout ? not unlike the bill of a duck ? that houses an impressive number of tiny, conical teeth.
“This fish has characteristics we just haven’t seen before in other clingfish. It’s the teeth that really gave away the fact that this is a new species,” said lead author Kevin Conway, a fish taxonomist and associate professor at Texas A&M University.
A detailed description of the new genus and species was published April 14 in the journal Copeia.
Scientists, including co-author Adam Summers of the University of Washington’s Friday Harbor Laboratories, are interested in clingfish for their ability to stick to rough surfaces. The finger-sized fish uses suction forces to hold up to 150 times its own body weight. Understanding the biomechanics of these fish could be useful in designing devices and instruments to be used in surgery, or to tag and track whales in the ocean.
Conway and co-author Glenn Moore of Western Australian Museum discovered the new clingfish while looking through specimens preserved in jars at the museum in Welshpool, Australia. It’s common for unknown specimens collected during surveys to be registered and shelved until an expert has the time, and interest, to take a closer look. This specimen was caught off the coast of Southern Australia in 1977. Even though the fish is only as big as a pinky finger, its unique teeth structure caught their attention.
A couple of hours later, Moore found yet another specimen with similar features on the museum shelves. Together, the specimens are thought to be the only two of this new species that exist out of water.
“A discovery like this highlights the importance of museum collections and reminds us just how much lies waiting to be uncovered,” Moore said. “Finding a previously unknown specimen in a jar is exciting, but our collections of identified specimens are equally important so that we have something to compare against.”
The researchers suspected they had discovered a new species that represented a new genus of clingfish, given the unusual mouth structure and teeth arrangement, but they were faced with a conundrum: Naming a new species requires an intact, complete fish with good documentation of its morphology and clear distinctions from other species. With only two known specimens, dissection was out of the question.
Instead they turned to Summers, who studies clingfish and is actively working to scan and digitize every fish species in the world using a computerized tomography (CT) scanner. Each completed scan is housed on Open Science Framework.
Using the scanner, the scientists were able to capture even finer details of the new clingfish than would be possible through manual dissection. They also used the digital scans to 3-D print parts of the fish in larger-than-life size to be able to analyze the mouth and jaw structures.
“This CT scan allowed us to take a completely noninvasive look at the entire skeleton of the fish, and it produced a gorgeous set of morphological photos that you couldn’t get from dissection,” Summers said. “It’s a testament to the importance of using these noninvasive methods of data collection.”
The scans allowed the researchers to hone in on the fish’s skeletal structure from many different angles and essentially digitally dissect parts of the fish. They estimate the tiny fish has between 1,800 to 2,300 individual teeth ? or 10 times what all other known clingfish have. The teeth point backward, which would suggest a gripping function, Conway said, but the researchers can’t be sure since the fish has never been observed in the wild.
The duckbilled clingfish joins the ranks of hundreds of new fish species that are described each year. It’s more unusual for these new species to be placed into a new genus ? in this case, the fish’s wider and longer upper jaw and abundance of tiny, dagger-like conical teeth were the sure signs of a brand-new genus.
The researchers are particularly pleased to have discovered a new clingfish in a region of Southern Australia that is known for its clingfish diversity and abundance.
“I think it’s remarkable that we would add to this diversity with yet another new genus,” Conway said. “It’s pretty special given this fauna is already pretty well-studied.”
This work was funded by the National Science Foundation.
For more information, contact Summers at email@example.com or 301-864-1491; Conway at firstname.lastname@example.org or 979-845-2620; and Moore at email@example.com or 61-8-9212-3744 (in Australia).
Related paper: http://www.asihcopeiaonline.org/doi/abs/10.1643/CI-16-560
Follow the #ScanAllFishes project on Twitter: https://twitter.com/hashtag/scanallfishes?lang=en
Duckbilled clingfish images: https://flic.kr/s/aHskSN9Mj3
Writer: Paul Schattenberg, 210-859-5752, firstname.lastname@example.org
Contacts: Melissa Meierhofer, 920-203-3668, email@example.com
Dr. Michael Morrison, 979-204-3015, firstname.lastname@example.org
COLLEGE STATION – The fungus that causes white-nose syndrome in hibernating bats has been detected on three species in the Texas counties of Childress, Collingsworth, Cottle, Hardeman, King and Scurry.
Bats play an important role in controlling insect populations that pose threats to Texas crops as well as assist in crop pollination. In 2011, the authors of the paper “Economic Importance of Bats in Agriculture” estimated the loss of bats to have a negative economic impact on U.S. agriculture of at least $3.7 billion annually. Recent studies indicate the value of insect control by bats to Texas agriculture is $1.4 billion annually, based on fewer crop losses from insects, reduced disease and less pesticide use.
The fungus was found in samples collected by a team from Texas A&M University’s Institute of Renewable Natural Resources and wildlife and fisheries sciences department, along with Bat Conservation International. The tested samples showed the fungus was present on tri-colored, cave myotis and Townsend’s big-eared bats.
“White-nose syndrome, which is caused by the Pseudogymnoascus destructans fungus, has already caused catastrophic bat losses in the eastern U.S. and is projected to be in Texas within the next few years,” said Melissa Meierhofer, a research associate at the Institute of Renewable Natural Resources in College Station. “The disease was first reported in New York 10 years ago and has been spreading to other bat populations at a distance of about 100 miles per year.”
Texas, with 32 bat species, has the greatest bat fauna diversity in the U.S., according to the Texas Parks and Wildlife Department. To date, bats with white-nose syndrome disease symptoms have been found in 30 U.S. states and five Canadian provinces. The fungus causing the disease has been discovered in three additional states as it makes its way across North America.
Since 2011, the TPWD has worked with Bat Conservation International to monitor caves in the Panhandle for the disease. In 2015, the agency funded a statewide project with the IRNR and wildlife and fisheries sciences focused on early disease detection and identification of bat populations before white-nose syndrome appeared.
Meierhofer said the fungus had previously been discovered within the past three years in bats wintering in the neighboring states of Arkansas and Oklahoma and that it was “only a matter of time” before the fungus and disease came to Texas.
“White-nose syndrome is only known to affect hibernating bats and has no direct health impact on humans,” she said. “The cold-adapted fungus causing the disease irritates the bat’s skin, disrupting its hibernation and causing it to deplete its store of fat. And while instances of the fungus in nearby states may not have resulted in the death of the infected bat, they still demonstrated the potential for the disease to occur in Texas and the need to be vigilant.”
Meierhofer said with assistance from the TPWD, Texas Cave Management Association, Texas Speleological Survey, Texas Department of Transportation, biologists and private landowners, the team surveyed a total of 223 sites in 2016 and 2017, which included caves, buildings, culverts, bridges and even one tree site.
In 2016, the team took swab samples from bats at eight cave sites in eight counties, but all samples tested negative for the fungus. In 2017, the team swabbed another 10 sites – two culverts and eight caves — in eight counties. Four of the cave sites had bats that tested positive for the fungus.
“Data from these surveys will help characterize suitable habitats where the fungus could appear so the agencies and organizations involved will be better prepared to manage the disease,” she said.
Maintaining healthy bat populations is critical, particularly for the agriculture industry, because certain bat species eat insects that can harm crops, said Dr. Michael Morrison, a professor of wildlife and fisheries sciences at Texas A&M in College Station and a co-primary investigator for the bat survey project.
“Also, without sufficient bat populations, there would be an increase in insects and that could lead to an increase in insect-vectored diseases,” Morrison said. “So accurate data on the species and populations of bats throughout the state will be helpful in protecting the bats susceptible to white-nose syndrome once it crosses into Texas.”
If the disease appears in Texas it could result in a much higher mortality for some bat species in the state, he said.
“Until we get a better handle on where the fungus and possible white-nose syndrome is located, we just cannot predict the ultimate consequences of how losing bats will affect the state’s agriculture,” Morrison said. “We’re still early in this evaluation and we just have to get out there and determine how large this problem is. That said, when the fungus arrived in other states, bats did develop white-nose syndrome and the population size of some species saw substantial declines.”
Fortunately, according to TPWD, the disease should not affect the Mexican free-tailed bat – the primary species in many popular Central Texas ecotourism sites – as this species has a short winter hibernation period.
Morrison said though there is no known cure for white-nose syndrome, numerous wildlife disease experts are actively working on treatments that may prove effective.
“There are some developing treatments for the fungus and the disease, but those will not be helpful if we cannot get a good handle on where the fungus is and how it is spreading,” he said. “Unfortunately, our current funding is not sufficient to sample as intensively as needed now that the fungus has been found in Texas.”
Study finds beauty in the eye of the beholder…and rivalry
Writer: Steve Byrns, 325-653-4576, email@example.com
Contact: Dr. Jessica Yorzinski, 979-845-5777, firstname.lastname@example.org
COLLEGE STATION – Flock, muster ostentation, cluster, lek, pulchritude, pride or bawl, no matter what a group of peacocks is called, Texas A&M University at College Station is now home to 40 of them, thanks to a Texas A&M AgriLife Research scientist.
Dr. Jessica Yorzinski with the university’s wildlife and fisheries sciences department, said her research flock arrived in College Station last fall and are settled in and happily enjoying Texas weather.
Yorzinski uses the birds to conduct a variety of behavioral studies. She trapped the original set from feral populations in Florida and California about eight years ago.
“I chose peafowl as study subjects because I was looking for a species in which males exhibited elaborate ornaments that females could use to assess their mates and other males could use to assess their rivals,” she said. “That was one reason, and the other reason was they are relatively large birds, so they are able to easily sport the equipment I use in my studies.”
One such study, Selective Attention in Peacocks During Assessment of Rival Males, was published in the Journal of Experimental Biology on March 15. The work and list of authors is available http://jeb.biologists.org/content/current. In the study Yorzinski looks through the eyes of the birds to actually see what the animals are paying attention to, in this particular case, how males size up their competition.
“It is important to understand how males are evaluating each other during the breeding season because their ability to compete with other males can impact their chances of copulating with females,” she said.
She found the males look at the lower regions of the other male’s display, mostly looking at the lower eyespot areas as well as the body of the rival. They also pay more attention to their rivals when said rivals are moving around or shaking their wings, but not when they are shaking their long train of decorative tail feathers. That particular movement apparently only interests the “girls.”
Yorzinski said peacocks set up territories, which they defend against rivals, and peahens visit these territories to check out potential mates.
“What we learned is that the males are evaluating similar traits when inspecting their rivals as females are evaluating when choosing their mating partners, but they are doing this, of course, for very different reasons.
“Competition among males can be costly in terms of energy expended and injuries, so males tend to spend a good amount of time, almost a third, sizing up the competition,” she said. “However, unless they are actively courting a peahen, the girls only get a glance from the males about 5 percent of the time.”
So how does one look through the eyes of a peacock? Yorzinski said that’s done through a novel approach called eye-tracking. The birds are equipped with cameras able to monitor their precise gaze behavior. The cameras were left on the birds about an hour as called for in the trial, so they didn’t have to wear the equipment continuously.
“Peafowl only mate a few months out of the year,” she said. “The males generally start displaying in early spring and continue until mid summer when they drop all their feathers and start growing a new set for the next season.
Since in the wild, being eaten by a predator is always a risk when one is distracted by too many stimuli or by a rival or prospective mate, the birds, both male and female, have likely evolved the ability to selectively shift their gaze among competing interests.
“It would be fascinating to extend this work to other species, including our own, to determine how animals are checking out their competition,” she said.
In the meantime, Yorzinski said one of the next projects she’s working on is using a system that tracks both of the birds’ eyes at the same time.
“So far, we’ve had to put a patch over one of their eyes due to technological limitations, so the next step is to look at all the visual information that the birds use and extend this current work into other contexts like navigation and foraging.”