Cholao, a small Lesser Yellowlegs (Tringa flavipes) is changing into a well known character amongst Audubon’s social media followers. Its migratory journey between the Cauca Valley, in southwestern Colombia, and the boreal forests of Canada, is monitored with a satellite tv for pc GPS transmitter that tracks its whereabouts, its motion, its epic crossing over the Gulf of Mexico till touching down in Louisiana, and its flight to the boreal forests of Canada.
Jorge Velásquez, Audubon’s Science Director for Latin America and the Caribbean, is maybe the one who is aware of probably the most in regards to the life and travels of Cholao —who is not only one, however a number of people— as he has spent a number of years monitoring not solely this particular hen, however the flights of 34 different “tringas,” as they’re informally known as. Along with his assist, we reply a few of the continuously requested questions on this hen and its spectacular journey.
How did the monitoring of those migratory birds get began, and why give attention to the Lesser Yellowlegs somewhat than one other species?
We started monitoring the actions of Tringa flavipes within the Cauca Valley, Colombia, in April 2022. Two components influenced this alternative: first, it is likely one of the shorebirds whose inhabitants has declined considerably; and second, it’s a species related to two crops intently tied to our work within the Cauca Valley — sugar cane and rice. This sparked our curiosity in studying extra about how lengthy these birds stay within the area throughout the wintering months, their migratory journeys, their origin, and their nesting areas within the boreal forests.
Have you ever at all times used the identical monitoring expertise, or has it modified over time?
It has modified! We began with Motus transmitters, despite the fact that there have been no Motus stations within the Cauca Valley that might detect them. Monitoring the actions of those tringas was not only a matter of becoming them with radio transmitters, but additionally establishing the infrastructure within the area to have the ability to monitor them. The truth is, of the primary 10 tringas we captured — throughout an train we did with Selva, a Colombian analysis and conservation group — we by no means knew once they left the nation, as a result of there have been no stations.
Motus has been the expertise wherein we’ve invested probably the most time and sources to trace the tringas. Nevertheless it has a significant limitation: it requires community protection, which is superb in the USA and in sure nations in Latin America. However as soon as the birds cross the border into Canada, particularly within the central a part of the continent, Motus protection may be very poor.
Does that imply we do not know what occurs to them?
Within the first two years of monitoring the 30 people we had tagged, we might lose monitor of them as soon as they handed via North Dakota. That’s the reason, in 2025, we began utilizing satellite tv for pc transmitters, which give us a greater document of native actions. This manner, we’ve already recognized the world the place they’re presumably nesting — and we are actually attempting to confirm it in particular person.
Do these birds observe the identical migration route annually, each on their method north and on their return to the Cauca Valley? How predictable are Lesser Yellowlegs?
I do suppose there are some patterns of their routes. We’ve got seen that, normally, throughout the spring migration, within the months of April and Might, birds appear to be in a race to succeed in their nesting grounds within the boreal area of North America. Essentially the most environment friendly route for that objective is the Midcontinent Flyway — virtually a straight line via all of the central states of the USA till crossing the border into Canada.
Within the fall migration, there may be extra variability: some undergo the central states and make stops alongside the way in which, in all probability gathering meals and vitality. Others take attention-grabbing detours: we’ve had tringas that enter via Minnesota and North Dakota, whereas others go all the way in which to New York and are available down the East Coast. There are additionally tringas that come down via the center of the nation and find yourself in Kentucky, Tennessee, South Carolina, and depart via Florida. And nonetheless others come down the identical route we’ve detected them utilizing throughout the spring migration.
In Cholao’s current journey, the route appears very very similar to a straight line — environment friendly.
That’s what we noticed with Cholao, tagged with GPS: it made virtually an uninterrupted two-and-a-half-day journey between Cali and the Louisiana coast. As quickly because it arrived in Louisiana, Cholao spent every week there — I think about recovering from the journey, feeding, and gathering vitality. From there it flew to Iowa, the place it stopped at a big swamp, absolutely stuffed with meals right now of 12 months. And from there it flew to its present space within the province of Saskatchewan, Canada.
One other fast reality about Cholao: how briskly does it fly?
Primarily based on what we’ve recorded, a minimum of throughout its ocean crossing and relying on components reminiscent of wind and climate, they common 25 to 30 miles per hour (45 to 50 kilometers per hour).
How is that this knowledge helpful to us, and the way does it inform decision-making?
Monitoring the actions of tringas and different birds permits us to establish the stopover websites of migratory birds — in different phrases, their “motels and eating places.” For this, the Motus community may be very helpful, since having knowledge from 30 or extra tagged people permits us to establish probably the most closely used areas, and thus get a greater concept of the threats they face alongside their migration route. As a corporation devoted to hen conservation, this enables us to start managing actions to deal with these threats.
And at a extra native scale — for which satellite tv for pc transmitters are very helpful — we are able to pinpoint precisely which land plots the tringas use, go to them, and examine what they do there, their environmental traits, and what could have an effect on them. With simply 5 people tagged with GPS, we have already got virtually 30,000 detections — a formidable quantity of knowledge that may assist decision-making at a really detailed scale.
What’s the gear the hen carries like? Does it make it considerably heavier or extra weak to predators or potential mates throughout the reproductive stage?
For each Motus transmitters and those who use satellite tv for pc positioning, the kind of transmitter is similar: a tiny backpack worn on the hen’s again, the place solely the form and weight fluctuate barely. The Motus transmitter is a bit flatter and lighter, weighing lower than two grams, whereas satellite tv for pc ones weigh round two grams.
Concerning the impact on particular person birds, there may be at all times a priority that they could influence mortality — not a lot as a result of they make them extra enticing as prey, however as a result of the harness can restrict mobility if it isn’t fitted appropriately. That’s the reason solely licensed personnel deal with the set up.
The opposite issue is that migration carries an vitality value, and people two grams could make an enormous distinction. In most species studied for migration, the intention is to maintain transmitter weight beneath three p.c of the person’s physique weight. Till just a few years in the past, it was unattainable to think about placing satellite tv for pc transmitters on a hen like Cholao — on a tringa — as a result of they had been all too massive. Now we are able to have transmitters beneath three p.c, which supplies us some peace of thoughts relating to the survival of the tringas. In any case, it should be evaluated with knowledge whether or not becoming the transmitters is having an impact on survival.
And what’s the lifespan of those transmitters? How do they work?
Each sorts of transmitters, GPS and Motus, use daylight to provide energy. Within the case of the Motus transmitters, they’ve a battery that recharges with daylight — as do the satellite tv for pc ones — and in idea they will final a number of years. Nonetheless, the longest we’ve managed to trace a single particular person is 2 years. It’s believed that this occurs because of put on and tear of the harness, which is manufactured from nylon and falls off.
With the info collected to date, what has stunned you?
I used to be anticipating a stronger affiliation between the tringas and pure habitats or wetlands. I imagined that within the Cauca Valley there could be a focus round Laguna de Sonso or the Cauca River. However no! The affiliation of the Lesser Yellowlegs with rice crops is unimaginable — virtually wherever there’s a rice crop, they’re there or will arrive.
This implies we’re heading in the right direction, and we should give attention to implementing bird-friendly practices within the Cauca Valley, the place these rice crops are a key piece of the migratory puzzle.
