African Giant Pouched Rats as invasive species

Danielle N. LeeDepartment of Zoology

Oklahoma State University

Problem with invasive species

• Disrupt local ecology– Overconsumes local resources– Displaces and/or eliminates locals in similar

guild/ecological niche– Introduces new diseases, parasites

• New Human-Wildlife conflicts– Agriculture pests– Zoonoses

This is the field where I found and trapped Cricetomys summer 2012 in Morogoro, Tanzania.This habitat is very similar to that of Southern Florida where Cricetomys have been found by the Florida Fish & Wildlife Authorities

Native habitat of African Pouched Rats

Wider view of the field site I used to trap and track African Pouched Rats, Summer 2012.Notice the open field in the foreground and the mixed woodlands in the back ground. Just behind this thin strip of trees was a small ravine or river.

My most successful trap, along the edge of the habitat of the open field and dense trees near a ravine (river).

Just under the thick of trees is the burrow I discovered when releasing animals from the traps.

The rats seemed to prefer dense habitats that provided cover.I only captured animals in the cover or along the edge, never in the open field.

A burrow I discovered while trapping and tracking Cricetomys Summer 2012.

Close up of the burrows created and used by African Pouched Rats. These are the burrows of rats in an outside enclosure.

Peterson et al. (2006) created a model predicting distribution of African Pouched rats if they were to able to establish a population in the United States.Given that ecological niche influences geographical potential and ecological behavior of a species can be invariant to community context, these invasive distribution models predict that the rats would obey the same ecological rules if they were in a novel setting (Peterson et al. 2006).Florida and the Southern United States would be ideal habitat for my rats.

African Pouched rats are very large, but reports of their size has been exaggerated. Adult rats range in size of 1 – 1.4 kg and 67-74 cm long – that includes the tail. (Perry et al. 2006). The largest rat I handled this summer was 1.7 kg and 80 cm long.

They are also long-lived rodents, up to 7 years in captivity. Fecundity is reported to be high ( up to 30 pups a year). However, my preliminary research indicates we know too little about the reproductive biology of this species to say that.

African Pouched Rats as Agriculture Pests

Palm nuts and corn kernels from the cheek pouch of a rat I was handling Summer 2012.

Star fruit from the orchard along the trapping line I used to capture, mark and recapture rats Summer 2012.

As agriculture pests, rodents cause an estimated annual lost of 5-15% of corn which is ~$45 million in crop and food loss in Tanzania alone (Stenseth et al. 2003).

I use bananas as bait for my trapping efforts, but citrus and other tropical fruits are local crops which are vulnerable to rodents. Florida, which has a similar ecology and orchard-agriculture industry could be devastated if the rats were to increase their numbers and extend their distribution.

African Pouched Rats as Zoonosis

• Infectious diseases that can be spread between species

• Great public health concern for diseases that can be transmitted from animal to humans

• Monkeypox• Lassa Fever• Leptospirosis

Key ReferencesNative-range ecology and invasive potential of Cricetomys in North America.AT Peterson, M Papes, MG Reynolds, ND Perry, B Hanson, RL Regnery, CL Hutson, B Muizniek, IK Damon, DS Carroll. 2006. J Mammalogy, 87(3):427-432

Rapid assessement for a new invasive species threat: the case of the Gambian giant pouched rat in Florida. R Engeman, JW Wollard, ND Perry, G Witmer, S Hardin, L Brashears, H Smith, B Muiznieks, B Constantin. 2006. Wildlife Research, 33:439-448

Monkeypox zoonotic associations: insights from laboratory evaluation of animals associated with the multi-state US outbreak. CL Hutson, KN Lee, J Abel, DS Carroll, JM Montgomery, A Olson, Y Li, W Davidson, C Hughes, M Dillon, P Spurlock, JJ Kazmierczak, C Austin, L Miser, FE, Sorhage, J Howell, JP Davis, MG Rynolds, Z Braden, KL Karen, IK Damon, RL Regnery. 2007. Am J Trop Med Hyg, 76(4): 757-767

New Invasive Species in Southern Florida: Gambian rat (Cricetomys gambianus). ND Perry, B Hanson, W Hobgood, RL Lopez, CR Okraska, K Karen, IK Damon, DS Carroll. 2006. J Mammalogy, 87(2)262-264

Mice, rats, and people: the bioeconomics of agriculture rodent pests. NC Stenseth, H Leirs, A Skonhoft, SA Davis, RP Pech, HP Andreassen, GR Singleton, M Lima, RS Machang’u, RH Makundi, Z Zhang, PR Bron, D Shi, X Wan. 2003. Front Ecol Environ, (7): 367-375