The delayed demographic responses of small mammals to habitat quality and density in the Brazilian Cerrado

Abstract

Understanding the effects of exogenous and endogenous factors on species demographic rates is crucial to investigate their chances of persistence on natural ecosystems. We used a 9-year time series, based on monthly captures, to test the delayed effects of endogenous (density) and exogenous (rainfall, habitat cover/heterogeneity, fire) factors on the survival and recruitment rates of two small mammals inhabiting the Brazilian Cerrado: the semelparous, scansorial marsupial Gracilinanus agilis and the iteroparous, arboreal rodent Rhipidomys macrurus. As in most short-lived small mammals, we found negative density-dependent effects on the recruitment of both species (3 months delay), which could occur through reduced immigration or fecundity, in addition to the semelparous breeding strategy of G. agilis. Reduced habitat cover following fire events had a negative delayed effect on the survival of G. agilis (3 months after) and R. macrurus (1 year after), albeit it increased the recruitment rates (1-year lagged effect) of R. macrurus. We failed to find any effect of fire on demography of either species. Our results suggest that the irregular and non-cyclical fluctuations in R. macrurus abundance were driven by the interaction between delayed density dependence and changes in habitat quality, while the marked and repeated fluctuations in G. agilis abundance were mainly shaped by the occurrence of semelparity associated with direct density dependence. We emphasize that changes in habitat quality brought by human-made activities may have severe impacts on the dynamics and persistence of forest-dependent small mammals in the Cerrado.

KEY WORDS:

• marsupials
• population dynamics
• recruitment
• rodents
• survival

Acknowledgments

We thank all the members (current and past) of Laboratório de Ecologia de Mamíferos at Federal University of Uberlândia, for help in the data collection of monitoring. C.P.R. Ferrando, M. Ferreira and A. Mendonça helped with suggestions that improved an earlier version of the manuscript. The Instituto de Biologia (INBIO/UFU) and Programa de Pós-Graduação em Ecologia e Conservação de Recursos Naturais/UFU provided logistical support.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

ETHICAL STANDARD

This study follows the guidelines and protocols declared in the American Society of Mammalogists (Sikes 2016) and the ethical principles on animal research as regulations of National Advice of Control and Animal Experimentation (CONCEA/Brazil) and was approved by the Ethics Committee on Use of Animals of the Federal University of Uberlândia, Brazil; Reference number 152/13 and 041/19. All animal experiments were approved by the Ethics Committee on Use of Animals of the Federal University of Uberlândia, Brazil; Reference number 152/13 and 041/19

AUTHOR CONTRIBUTION

R.C. Rossi and N.O. Leiner originally formulated the idea, N.O. Leiner developed methodology and R.C. Rossi conducted fieldwork. R.C. Rossi analyzed the data and R.C. Rossi and N.O. Leiner wrote the manuscript.

SUPPLEMENTAL DATA

Supplemental Data for this article can be accessed at https://doi.org/10.1080/03949370.2023.2248592

Additional information

Funding

This study was financed in part by the [Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil] under Grant [number 001]; [Fundação de Apoio à Pesquisa do Estado de Minas Gerais] under Grant [PELD APQ-03202-13 and APQ-04815-17]; and [Conselho Nacional de Desenvolvimento Científico e Tecnológico] under Grant [CNPq PELD 441225/2016-0 and CNPq PELD 441142/2020-6].