Deadly Fungus Makes Sick Frogs Jump Farther—Possibly in a Desperate Search for Mates

Across the world, frog populations are declining at an alarming rate, and one of the biggest threats is a microscopic fungus known as chytrid fungus (Batrachochytrium dendrobatidis, often called Bd). This pathogen infects the skin of amphibians, causing a disease called chytridiomycosis, which has contributed to mass die-offs of frog species on multiple continents.

But recent scientific findings reveal a surprising twist:
Infected frogs may jump farther—not less—than healthy frogs.
Researchers believe this unusual behavior could be an instinctive attempt to find mates before the disease overwhelms them.

A Deadly Fungus With a Strange Effect

The chytrid fungus attacks a frog’s skin—an organ they rely on for breathing, hydration, and regulating essential body functions. Typically, infected frogs become weak and sluggish. But the new study found that some species behave very differently during the early or mid-stage of infection.

Key finding: Sick frogs jump farther than healthy ones

Experiments showed that infected male frogs pushed themselves to perform longer and more forceful jumps, despite carrying a harmful infection.

Scientists believe this may be a form of terminal investment—an evolutionary strategy where an animal increases its reproductive effort when its future survival drops.

In simpler terms:
The frogs may be instinctively taking bigger risks and using more energy in an effort to find a mate while they still can.

Why Would Sick Frogs Try to Jump Greater Distances?

Researchers suggest three main reasons:

1. A “last chance” reproductive push

Disease can signal to the frog’s body that its life expectancy is short. To maximize survival of its genes, the frog may put extra effort into finding a mate.

2. Avoiding infected areas

Jumping farther may help a frog escape disease-hotspots or environments where fungus thrives.

3. Stress-induced overactivity

Illness often triggers stress hormones. These hormones may temporarily increase activity levels, even as the infection worsens over time.

Why This Discovery Matters

This behavior could influence how scientists understand—and protect—frog populations struggling with chytrid infections.

Conservation implications:

• Better disease monitoring:
  Increased movement from infected frogs may spread the fungus faster between habitats.
• Improved breeding programs:
  Understanding reproductive behavior can help conservationists plan protected breeding zones.
• Insights into survival strategies:
  Knowing how frogs behave under stress helps scientists predict population changes and recovery potential.

A Reminder of How Complex Wildlife Responses Can Be

Nature often responds to threats in unexpected ways. The discovery that a deadly pathogen can push frogs to leap farther highlights how animals adjust their behavior—sometimes in the last moments of survival—to keep their species alive.

While chytrid fungus remains one of the biggest challenges in amphibian conservation, research like this deepens our understanding of how frogs fight back, even when the odds are stacked against them.

References

1. Greenspan, S. E., et al. (2024).
   “Pathogen infection alters locomotor performance in male frogs: increased jumping associated with chytrid fungus.”
   Current Biology.
   – The primary study showing that male frogs infected with Batrachochytrium dendrobatidis (Bd) jump farther, possibly due to terminal reproductive investment.
2. Scheele, B. C., et al. (2019).
   “Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity.”
   Science, 363(6434), 1459–1463.
   – Summarizes global impacts of chytrid fungus and its role in amphibian declines.
3. Voyles, J., et al. (2009).
   “Pathogenesis of chytridiomycosis, a cause of catastrophic amphibian declines.”
   Science, 326(5952), 582–585.
   – Describes how Bd damages amphibian skin and disrupts essential bodily functions.
4. Berger, L., et al. (1998).
   “Chytridiomycosis causes amphibian mortality associated with population declines.”
   Proceedings of the National Academy of Sciences (PNAS).
   – The foundational study identifying Bd as a major amphibian pathogen.
5. Longcore, J. E., et al. (1999).
   “Batrachochytrium dendrobatidis gen. et sp. nov.”
   Mycologia.
   – The taxonomic description of the chytrid fungus.
6. IUCN Amphibian Specialist Group.
   Global Amphibian Assessment Database
   – Provides information on amphibian declines, threats, and conservation status worldwide.
7. AmphibiaWeb (University of California, Berkeley).
   – Offers detailed species accounts, disease summaries, and updates on Bd outbreaks.