In the American state of Florida , rancher Jim Strickland can see his cows at any time , day or night .
To do this , all he needs is his phone .
Strickland uses virtual fencing to watch and control the movements of his animals .
It can also help improve animal health .
Strickland has been using the system for about six months .
“It has exceeded by far my expectations .”
Virtual fencing uses radio signals to make an invisible fence .
This means you cannot see the fence .
This keeps animals within , or outside of , certain areas .
The signals come from nearby mobile phone towers .
The signals can also come from base stations that can be moved using a small truck .
Each animal wears a collar around its neck .
The collar has a radio signal receiver and a GPS device that shows the animal's location .
Ranchers train livestock to connect a sound with a small electric shock .
When an animal gets close to a virtual fence , its collar makes a warning sound .
If the animal moves even closer to the fence , it receives a shock .
In this way , livestock quickly learn to stay away from the fence .
Ranchers can change the virtual fence boundaries quickly by using a phone App or computer .
And livestock quickly learn the new boundaries .
Strickland and his coworkers can use their phones even while on horseback to move cattle from one area to another .
All they need to do is change the virtual fence lines .
“And every 30 minutes , that line will move down ; it will literally drive those cows down .”
Physical fences take time , labor and money to build .
It can be difficult to put them in areas such as rocky and hilly land , wet areas , or places with thick vegetation .
Over time , fences need to be fixed or new ones need to be built .
When hurricane Ian hit Florida last year , it destroyed four houses and 45 kilometers of physical fence on the land where Strickland works .
But the cell towers for the virtual fence system kept working .
Physical fences can also harm wild animals by making it difficult for them to move within and to areas they need for survival .
The Nature Conservancy (TNC ) is a U.S-based environmental non-profit organization .
It has partnered with cattle ranches in the states of Kansas , New Mexico and Colorado to research the effects of virtual fencing .
William Burnidge is Deputy Director of TNC's North America Regenerative Grazing Lands Strategy .
He said that by changing fence boundaries , the systems prevent animals from eating too much vegetation within one area .
This helps plants regenerate , or grow again .
He added that virtual fences could help protect rare plants and areas near rivers and streams .
They could also support conservation of wild animals , improve the health of animals and help ranch workers have a better quality of life .
Strickland works with partners at Florida Conservation Group and the University of Florida .
With virtual fences , they can carefully control grazing .
This helps them research the effects of grazing patterns on the growth of young cows , birth rates , and even the effects on nesting birds .
They also plan to research how grazing can affect the release of carbon dioxide gas into the atmosphere .
In Florida and other places , fields are sometimes burned to prepare them for future grazing .
The burning releases carbon .
Virtual fences may help reduce burning by better controlling where and how long cattle graze .
Both Strickland and Burnidge note that , unlike physical fences , livestock cannot not get injured by a virtual fence .
The GPS collars also let ranchers watch for animals that may be having problems .
For example , if the system shows that a cow has not moved for many hours , it may be sick or injured .
Cattle can easily damage burned areas and the young plants that grow there .
The Oregon study showed that cows without virtual fence collars ate nearly 70 percent of the plants available to them in a burned area .
However , cows with collars spent very little time in the burned area and ate less than three percent of the plants available to them .
Although virtual fencing systems have benefits , they can be costly .
A collar for just one animal can cost around $50 each year or more .
And portable base stations cost $10,000 or more .
Researchers are looking for ways to lower costs and bring the technology to developing countries .
Last year , the Bezos Earth Fund awarded $9.9 million to Cornell University's College of Agriculture and Life Sciences to develop low-cost virtual fencing .
The university plans to test new systems in Kenya , Mongolia , Argentina , Brazil and Colombia .
But in some areas , virtual fencing may not be the best solution , Burnidge said .
When Burnidge visited Kenya , he saw many workers who closely follow and take care of livestock .
Virtual fences could cause some of these workers to lose their jobs .
Still , Burnidge said , many people want to learn more about the technology .
And Strickland said they are already working on more ways virtual fencing can be used .
“Now we're seeing so many things .
Once you start down the road of new technology , then it starts expanding . . .
It's like , what can we do next ?” he said .