We first collared FP-153 in the Deep Lake Unit on February 19, 2007 She did not have a transponder, so was estimated to be 6 years of age.  She was in good health and weighed 88 lbs. We also treed 2 kittens estimated at 10-11 months of age and the houndsman saw a third kitten. None of these were handled.

FP-153’s 10-11 month old daughter.

FP-153 running through sawgrass June 13, 2007.

 FP-153 was re-collared on March 3, 2008. She was in good health and weighed 85 lbs.

In July 2008 FP-153 denned. Deborah Jansen tells that story below.

Panther Kitten “ACE” is Dealt an Unlucky Hand

FP-153 was with male FP-138 for two consecutive surveillance flights early in April 2008, and then located with another male FP-133, during the next two flights.

Since gestation for panthers is just over 3 months, we began watching from the air, early in July, for her to settle in to den. And she did. She chose a palmetto thicket in northern Airplane Prairie on the Turner River Unit of Big Cypress. It was only a straight-line distance of 2.5 miles from Turner River Road, but for us, a 5 mile, 1.5 hour swamp buggy trip, one-way. On July 9, 2008 we set up the biologist-in-a box to monitor her den.

On Sunday, July 20th, FP-153 was away from her den, so we searched for the kittens, and found them after 18 minutes, hidden in the dense palmetto. I only spotted two kittens resting side-by-side so asked Annette Johnson, (BCNP research team member) who had approached from another angle, to slowly crawl through the palmetto toward me and look for additional kittens. She did, indeed, find a third one under dried palmetto fronds at the far edge of the den.

K-274. 275, and 276 in their den

We weighed and marked via transponder two males and one female. All were healthy, weighing around three pounds each at three weeks of age. They were now kittens #274, 275, and 276.

K-274, K- 275, and K-276

One research priority is to obtain more accurate information on kitten survivorship between the time we mark them at the den and when they are 6-months-of- age. The better the data that goes into panther population modeling, the better the results. One technique of documenting kitten survival has been to check the original den for kitten remains and scan the site for transponders after the mother has moved the litter to another den. At FP153’s den we used the added technique of placing two specialized trail cameras outside the den. Since they emit neither sound nor flash, we expected these cameras not to influence FP153’s or her kittens’ behaviors. We also hoped that the cameras’ odor would not linger more than what scent we left behind.

Trail camera in den.

FP-153 returned to the den between 7 and 8 PM on the day we handled the kittens, yet, to our surprise, we did not hear her signal via the remote phone after that. Several things could explain this. Either the monitoring box wasn’t working, or FP-153 was coming back during the time her collar automatically shut off at night, or she had abandoned the den. Our routine fixed-wing flights indicated that she had indeed moved the den 275 yards southeast of the original, so we could now go in and retrieve the cameras.

We arrived at the “old” den site Sunday, July 27, 2008 one week after marking the kittens. As Ralph Arwood (BCNP research team member) approached the den, he heard plaintive crying. Male K-275 was still at the original den! With a wicked storm threatening, we pulled the cameras and collected K-275 who had lost 40% of his body weight in that week.

K-275 alone at the den.

Many questions tumbled through our minds as we made the long wet buggy trip back to the road with K-275 dry and nestled among pillows in a large cooler, crying for food. “When did FP-153 move her kittens to the second den?” “Why had she left K-275 behind?” “Could we get him back to his siblings?”

Back at BCNP headquarters, with only a little coaxing, K-275 welcomed the warm KMR (kitten milk replacement) and comfort of his temporary “den” of towels in a Rubbermaid storage bin.

While he slept, the events of the past week in the den, as documented by the field cameras, were unfolding on Ralph’s computer screen. Some of the 850 shots which had an animal in view told us that FP-153 had returned to the den at 7:22 PM on the day we first handled the kittens. We also saw that for the next two days, only two opossums wandered through the cameras’ beams. The kittens were likely just out of range of the cameras, because early Wednesday morning the whole family was visible. At 4:07 AM that day, FP-153 picked up one kitten in her mouth and walked off. The remaining two kittens were then photographed, sometimes sleeping, sometimes playing.

FP-153 at her den.

At 9:04 AM, FP-153 returned, picked up another kitten and walked off. For the rest of that day and the following three days, the cameras recorded only K-275, first quiet in the den, then progressively wandering back and forth through the cameras’ beams. In the later shots, his mouth is often open in a cry that the cameras do not record.

The day after K-275 was retrieved, we briefed FWC veterinarian Mark Cunningham and other agency staff on our findings and strategized on how best to return the kitten to his mother and siblings. Our challenge was to determine FP-153’s new den location through triangulation and find it while she was off hunting. Monday’s flight told us that FP-153 was at the den, so that evening, after the storms had dissipated, we set up the monitoring box near her new den and secured a more accurate location from the ground.

We got out of the woods at 11:00 that evening, only to start in again before daylight the next morning, this time with K-275 in hand.
When we approached the den area, we could hear FP-153’s signal an estimated half-mile southeast of the den. “Was she returning?” “Did we have time to find the den and get K275 back with his siblings?” We decided to give it a try. We found the den in four minutes, and noticed a kitten quietly laying at its edge. We set K-275 down between two palmetto roots that would funnel him to his sibling. As he crawled toward the other kitten, it gave a startled spit. But it soon calmed as K-275 crawled over it, purring loudly. We quickly left. As of August 5, 2008 a week after we returned K-275, FP-153 was still coming back to the second den.

We will never know why FP-153 left K-275 behind. We will only know if K-275 was accepted and raised by his mother if, one day, we scan the back of a tranquilized adult male panther and the screen displays “695ACE5”. By coincidence, the word “ACE” was part of his unique transponder number. We hope that’s a lucky sign. 

FP-153 denned again in June of 2009.  She made us work for this den. It’s location was even more remote than K-275’s den, with a longer rougher buggy ride to get there. It took us multiple attempts to find the kittens in very dense sword fern. The July heat and mosquitos made for an exhausting search.


Entrance to den.

K-281 and K-282 in den

On July 8, 2009 we handled 2 male kittens, K-281 and K-282.

We could not handle FP-153 during the 2009-2010 capture season because her kittens were less than 12 months of age and her collar battery failed on August 22 2009.

FP-153 February 19, 2012.

On February 19, 2012 Houndsman Rocky McBride’s dogs treed FP-153 in the Turner River Unit. The dogs also found a near by den with four kittens. Rocky quickly secured the kittens in the empty dog box on his buggy while the rest of the team converged on the site. It was decided that the best course was to change FP-153’s collar and mark the kittens.

Kittens in dog box

Her 4 male kittens were about nine days old and weighed between 1 lbs 4 oz and 2 lbs 1 oz. Two of the kittens did not look healthy.

On February 23, 2012 after FP-153 had relocated her den we returned to the original den.  We found the remains of K-351. He was the smallest of the four kittens we had handled four days earlier. It appeared that he had died in the last 24 hours.    

K-348 and K-351 at den

We also found a K-348 at the den.  His weight had dropped from 1 lbs. 12 oz. to 1lbs. 7 oz. but he other wise appeared healthy.  After giving him some kitten milk replacement formula he was placed within 30 meters of the estimated location of FP153’s second den when FP-153 was there and could hear him vocalizing.


FP-153’s movements over the next several months indicated that she was caring for her kittens.

In June of 2015, FP-153 was found to be in the same cypress dome on three tracking flights. On the third flight her collar was in mortality mode. Her body was recovered on June 16, 2015. She was found floating in a gator pond. Her skull had been crushed. Due to the amount of decomposition the cause of her death could not be determined. She was 14 years old.

© Ralph Arwood 2019