Body morphometry and reproduction of the field rat Sigmodon hirsutus (Rodentia: Cricetidae) in Costa Rica

Body morphometry and reproduction of the field rat Sigmodon hirsutus (Rodentia: Cricetidae) in Costa Rica

Authors

  • Javier Monge Universidad de Costa Rica, Escuela de Agronomía, Centro de Investigación en Protección de Cultivos, Facultad de Ciencias Agroalimentarias, Instituto de Investigaciones Agrícolas, San José, Costa Rica; https://orcid.org/0000-0003-1530-5774

DOI:

https://doi.org/10.22458/urj.v12i1.2887

Keywords:

Rodents, reproduction, morfology, pineapple, Costa Rica

Abstract

 Introduction: The rat (Sigmodon hirsutus) is common in agricultural environments in Central America. Of this species little biological and ecological information is available, given its recent reclassification as a species. Objective: To describe the body morphometry, used in turn as a criterion of body condition and to determine your reproductive cycle of the field rat. Methods: The study was carried out in the canton of La Cruz, Province of Guanacaste, Costa Rica from March 2009 to April 2010. I did 29 fortnightly samplings of three consecutive nights on organic pineapple crops. I measured the length and weight of individuals to establish a relationship between these variables and use them to estimate the body condition index. I determined the reproductive cycle based on the state of pregnancies, presence of juveniles, and in complementary form the testicular position in males. By body characteristics and reproductive activity, age categories were defined. Results: I collected 418 specimens of S. hirsutus, for a sex ratio of 1:0.6 (male:female). Males are bigger and heavier. The body condition index (mm/g) ranged from 1 to 6,4 for males and between 1 and 8,3 for females, with an inverse relationship to the weight category. Of the 154 females collected, 36,4% were pregnant, all of which were present in all months and most often in April 2009, June and August. The presence of juveniles was greatest in April 2009 and June, although they were present in almost every month of the year. The scrotal position of testicles was the most common (54,4%). The age categories being represented throughout the year, suggesting a reproductive activity for the species and site throughout the year. Conclusion: The rat S. hirsutus is of medium size (141,65mm and 84,13g and 131,81mm and 69,07g, for males and females, respectively), and presents sexual dimorphism. Reproductive activity occurs throughout the year.

References

Bowdre, L. P. (1971). Litter size in Sigmodon hispidus. The Southwestern Naturalist, 16(1), 126-128. DOI: 10.2307/3670111
Cameron , G. N., & McClure, P. A. (1988). Geographic variation in life history traits of the hispid cotton rat (Sigmodon hispidus). En: Boyce, M. S. (Ed.) Evolution of life histories of mammals. Theory and pattern. (pp. 33-64). Connecticut, USA: Yale University Press.
Cameron, G. N., & Spencer, S. R. (1983). Field growth rates and dynamics of body mass for rodents in the Texas Coastal Prairie. Journal of Mammalogy, 64(4), 656-665. DOI: 10.2307/1380522
Carroll, D. S., & Bradley, R. D. (2005). Systematics of the genus Sigmodon: DNA sequences from betafibrinogen and cytochrome b. The Southwestern Naturalist, 50(3), 342-349. DOI: 10.1894/0038-4909(2005)050[0342:SOTGSD]2.0.CO;2
Chipman, R. K. (1965). Age determination of the cotton rat (Sigmodon hispidus). Tulane Studies in Zoology, 12(2), 19-38.
Fleming, T. H. (1970). Notes on the rodent faunas of two Panamanian forest. Journal of Mammalogy, 51(3), 473-490. DOI: 10.2307/1378388
Goertz, J. W. (1965). Sex, age and weight variation in cotton rats. Journal of Mammalogy, 46(3), 471-477. DOI: 10.2307/1377636
González, R. A., Sandoval, T., Serna S. J., & Aguilar R., V. M. (1978). Damages caused by cotton rat, Sigmodon hispidus zanjonensis, on sugar cane in San Pedro Sula, Honduras. Howard, W.E. (Ed.) Proceedings of the 8th Vertebrate Pest Conference. University of Nebraska – Lincoln, Sacramento, California, USA.
Heikura, K. (1977). Effects of climatic factors on the field vole Microtus agrestis. Oikos, 29(3), 607-615. DOI: 10.2307/3543599
Hilje, L. (1992). Biología y ecología de los roedores plaga en Costa Rica. Manejo Integrado de Plagas (Costa Rica), 23,17-25.
Jiménez, J. J. (1971). Comparative post-natal growth in five species of the genus Sigmodon. I. External morphological character relationships. Revista Biología Tropical, 19(1,2), 133-148.
Krebs, C. J., & Singleton, G. R. (1985). Indices of condition for small mammals. Australian Journal of Zoology, 41, 317-23. DOI: 10.1071/ZO9930317
Layne, J. N. (1974). Ecology of small mammals in a flatwoods habitat in north-central Florida, with emphasis on the cotton rat (Sigmodon hispidus). American Museum Novitates, 2544, 1-48.
Meyer, B. J., & Meyer, R. K. (1944). Growth and reproduction of the cotton rat, Sigmodon hispidus hispidus, under laboratory conditions. Journal of Mammalogy, 25(2), 107-129. DOI: 10.2307/1375009
Monge, J. (2008). Estructura poblacional y actividad reproductiva de la rata de campo (Sigmodon hirsutus) durante un ciclo de producción de maní (Arachis hypogaea) en Costa Rica. Agronomía Costarricense, 32(2), 161-167.
Monge, J. (2010). Comparación de trampas de golpe de diferente tamaño en la captura de ratas Sigmodon hirsutus (Cricetidae). Agronomía Costarricense, 34(2), 251-258.
Odum, E. P. (1955). An eleven year history of a Sigmodon population. Journal of Mammalogy, 36(3), 368-378. 10.2307/1375679 DOI:
Peppers, L. L., Carroll, D. S., & Bradley, R. A. (2002). Molecular systematics of the genus Sigmodon (Rodentia:Muridae): evidence from the mitochondrial cytochrome-b gene. Journal of Mammalogy, 83(2), 396-407. DOI: 10.1644/1545-1542(2002)083<0396:MSOTGS>2.0.CO;2
Vivas, A. M., & Calero, A. C. (1985). Algunos aspectos de la ecología poblacional de los pequeños mamíferos en la estación Biológica de Los Llanos. Boletín de la Sociedad Venezolana de Ciencias Naturales, 143,79-99.

Published

2020-05-25

How to Cite

Monge, J. (2020). Body morphometry and reproduction of the field rat Sigmodon hirsutus (Rodentia: Cricetidae) in Costa Rica. UNED Research Journal, 12(1), e2887. https://doi.org/10.22458/urj.v12i1.2887

Issue

Section

Articles
Loading...