Three captive-reared saltwater crocodiles did not show movement toward their former husbandry sites after release, while the only wild crocodile moved to a new area traveled consistently toward his former capture area. He never got back there during the 53–127-day tracking period. The contrast comes from a five-animal study in Bangladesh’s Sundarbans, so it is an important early result—not a universal rule about every crocodile.
The short answer
A 2026 study followed five mature saltwater crocodiles (Crocodylus porosus) after release in the Sundarbans mangrove ecosystem of Bangladesh. Three had been raised in captivity. One wild crocodile was released near where he had been caught, and another wild crocodile, named Jongra, was moved to a different area before release.
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The three captive-reared animals established comparatively compact ranges and showed no indication of homing toward their former husbandry sites during tracking. The locally released wild crocodile also remained within a relatively small range. Jongra behaved differently: he traveled much farther, reached a maximum reported daily movement of 34.3 kilometers, and occupied a 2,515-square-kilometer home range while moving consistently in the direction of his former capture area. He did not complete the trip during the study.
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What the study was designed to find out
The researchers asked what “home” means to a mature saltwater crocodile after release. A crocodile that has been moved may orient toward its capture site, while an animal raised by people may have no equivalent wild location to navigate back to. Comparing those release histories can show whether post-release movements differ according to an animal’s previous experience.
The work was led by Ruchira Somaweera and coauthors and published on 23 March 2026 in Wildlife Research (volume 53, issue 4, article WR25141; DOI 10.1071/WR25141). The study took place in the Sundarbans, a network of tidal rivers, creeks, mudflats and mangrove forest where saltwater crocodiles move through both freshwater-influenced and brackish habitats.
The five release histories
- Three captive-reared crocodiles: mature animals that had spent extended periods in captivity before release.
- One locally released wild crocodile: caught in the wild and released near the original capture area.
- Jongra: a wild-caught crocodile moved to a different release area, making him the study’s sole translocated animal.
Because only one crocodile experienced long-distance translocation, the comparison is informative but narrow. Jongra’s behavior is a case study, not a population estimate.
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How researchers measured movement
Each crocodile carried a satellite-tracking device. The tags supplied repeated location data while the animals moved through the Sundarbans. Tracking lasted between 53 and 127 days per animal, depending on the individual.
To interpret those locations, the researchers used continuous-time state-space modeling. This statistical approach estimates an animal’s likely path between observations and separates movement patterns from gaps or uncertainty in the transmitted data. It also allowed the team to estimate a daily movement distance and a home-range area for each crocodile.
A home range is the area an animal uses over the observation period; it is not necessarily a defended territory, a permanent lifetime range or proof that every part of the area was used equally. Likewise, “homing” in this context means movement oriented toward a former capture or husbandry location. It does not require that the animal reach that destination.
What each crocodile did after release
| Release history | Movement consistent with homing? | Reported movement and range | What can be concluded |
|---|---|---|---|
| Three mature captive-reared crocodiles | No indication of movement toward former husbandry sites during tracking | Shorter daily movements than Jongra; home ranges fell within 14.2–125 km² | These animals established relatively defined ranges during 53–127 days of observation |
| Wild crocodile released near capture area | No unusual long-distance return movement reported | Home range included within the 14.2–125 km² range reported for captive-reared and locally released wild animals | Releasing near the capture area did not produce Jongra’s extensive movement pattern |
| Jongra, wild-caught and translocated | Yes, movement consistently pointed toward his former capture area, although he did not return during the study | Maximum daily movement: 34.3 km; estimated home range: 2,515 km² | One translocated crocodile showed unusually extensive movement consistent with homing |
The range difference was substantial. The 14.2–125 km² estimates for the three captive-reared crocodiles and the locally released wild crocodile were far smaller than Jongra’s 2,515 km² estimate. Exact daily-distance values for each of the other four crocodiles were not stated in the reported findings; the study describes them as moving shorter distances than Jongra.
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Why Jongra’s route looks like homing
Jongra did not simply wander in a large circle. His locations showed a consistent directional tendency toward the area where he had originally been captured. That is why the authors describe his movements as consistent with homing.
He nevertheless failed to reach the former capture site during the tracking window. Several explanations are possible in principle: the distance and tidal landscape may have slowed travel, the crocodile may have changed course, or the observation period may have ended before a return. The study does not establish which explanation applies. The evidence supports a directional movement pattern, not a completed journey or a demonstrated navigational mechanism.
Behavioral ecologist and study author Ru Somaweera described crocodilians as “the largest predators in most tropical, subtropical freshwater and brackish environments” and “a unique case when it comes to homing behaviour.” Their size, aquatic mobility and ability to move through connected waterways make them especially useful for studying how release location interacts with prior experience.
What the captive-reared result means
None of the three captive-reared crocodiles showed indications of homing toward the places where they had been kept. Instead, they occupied smaller, more defined ranges during the months they were tracked. That pattern suggests that mature captive-reared crocodiles can settle into a release landscape without immediately attempting to travel back to a former facility.
The result should be stated narrowly. It applies to these three animals, their release conditions and the 53–127-day tracking periods. It does not demonstrate that captive-reared crocodiles lack spatial memory, cannot move long distances later, or will always remain near a release site. It also does not by itself establish survival rates, body condition, breeding, recruitment or long-term population growth.
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Those qualifications are important for conservation decisions. A compact early home range may indicate successful short-term establishment, but movement data alone cannot show whether an animal finds enough food, avoids people, reproduces or survives across seasons.
Why release history changes the risk
The comparison points to a practical difference between two kinds of release. A captive-reared crocodile has no known former wild territory to revisit. A wild crocodile that is moved away from its capture area may retain a strong orientation toward familiar habitat.
Jongra’s response illustrates the management problem. A translocated crocodile that travels hundreds of kilometers through rivers and mangroves can cross boundaries, enter areas used by people or expend energy before settling. The larger the release distance, the more difficult it may be to predict where the animal will go and what conflicts or ecological effects may follow.
Somaweera summarized the implication for managers: “For translocated crocodiles, it’s important there is careful release planning to manage their tendencies to return home.” Planning does not mean that every translocation will fail. It means that release sites, distances, timing, monitoring and contingency actions should account for the possibility of a return attempt.
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Questions a release plan should address
- How far is the release site from the capture area? Jongra’s movements show why distance and direction matter.
- Are waterways connected? Tidal channels can provide routes for rapid travel and carry an animal into unexpected areas.
- What human-use zones lie along likely routes? Fishing grounds, villages and boat traffic may become conflict points.
- How long will monitoring continue? A 53-day track may capture a different phase of movement than a 127-day track.
- What happens if the crocodile keeps moving? Managers need agreed responses before release rather than improvising after a long-distance excursion.
Does this prove captive release is better than translocation?
No. The study does not compare two large, randomly assigned groups, and it does not measure all the outcomes needed to rank conservation strategies. It compares three captive-reared crocodiles, one locally released wild crocodile and one translocated wild crocodile under observational conditions.
The authors do see potential in releasing mature captive-reared crocodiles. Their conclusion is that such releases may be a viable strategy for strengthening wild populations, provided that other requirements for a successful conservation program are met. “Viable” is a possibility supported by the observed movement pattern, not a guarantee of survival or a recommendation to release animals without site assessment.
Translocation can still be appropriate in situations where moving a wild animal is necessary. The evidence instead argues for more deliberate design: choose locations with suitable habitat, anticipate directional movement, reduce conflict opportunities and use telemetry or other monitoring to detect unexpected travel.
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What the five-animal sample cannot answer
- How common homing is: one translocated crocodile cannot provide a population-wide rate.
- Whether sex, age or body size changes the response: the reported comparison does not establish those effects.
- How seasons alter movement: tracking lasted months, not a complete multi-year cycle.
- Whether compact ranges persist: the captive-reared animals may have moved differently after the tracking ended.
- Whether the releases increased the population: reproduction and long-term survival were not established by movement observations alone.
- Why Jongra oriented toward his former area: the pattern is clear, but the sensory cues or memory processes behind it remain unresolved.
These limits do not erase the finding. They define its proper scale: an early, closely observed comparison that identifies a management issue and a promising avenue for further study.
How to read the headline accurately
“Three captive crocodiles stayed free” is a concise way to say that the captive-reared animals did not show a return movement toward their former husbandry sites during observation. “The wild one tried to go home” refers to Jongra’s directional movement toward his former capture area, not to a verified arrival.
The most defensible takeaway is therefore conditional: in this small Sundarbans study, mature captive-reared crocodiles established relatively limited ranges, while the single wild crocodile moved to a new area traveled extensively toward his former range. Future releases should treat those histories as different behavioral starting points.
Quick Recap
Study at a glance
- Species: saltwater crocodile (Crocodylus porosus).
- Location: Bangladesh’s Sundarbans mangrove ecosystem.
- Animals: five mature crocodiles.
- Tracking method: satellite telemetry analyzed with continuous-time state-space modeling.
- Tracking duration: 53–127 days per animal.
- Jongra’s maximum daily movement: 34.3 km.
- Jongra’s estimated home range: 2,515 km².
- Range for the three captive-reared and locally released wild crocodiles: 14.2–125 km².
- Publication: Wildlife Research, published 23 March 2026.
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