conservation.arizona.edu - small mammal

Exotic Pet Trade as a Cause of Biological Invasions: The Case of Tree Squirrels of the Genus Callosciurus

aburnett93 — Fri, 22 Oct 2021 21:53:17 +0000

Authors

Maria Vittoria Mazzamuto

Lucas Wauters

John Koprowski

The pet industry is a growing global multibillion dollar market. The increase of exotic and non-domesticated animal ownership has led to an increase in the number of non-native pets released that create invasive alien species (IAS) populations in the wild. IAS negatively impact the biodiversity, human health and countries’ economies. We use tree squirrels of the genus Callosciurus as a well-documented case study of pets that become IAS. We review the pathways and range of introduction and the challenge and legal importance of species identification. Next, we document how they negatively affect native plants and animals, their parasitic infections that can threat native wildlife and human health and their impact on human activities and productive systems. We discuss the diverse biological, social, political and economic reasons that make control/eradication of these charismatic species difficult in most countries. However, we also highlight the successful management of the IAS in two countries where the early detection and engagement of stakeholders were key to successful eradication. We conclude that efforts to educate and involve the broader public by actively engaging a diversity of stakeholders are more likely to build a consensus toward IAS management and should be a priority for each country.

Additional Information

Biology

Date of publication:

2021

Topics

small mammal

Research Categories

Human Wildlife Conflict Invasive Species

Multiscale effects of habitat loss and degradation on occurrence and landscape connectivity of a threatened subspecies

aburnett93 — Fri, 22 Oct 2021 21:47:19 +0000

Authors

Kira Hefty

John Koprowski

Land use change can result in complex environments of varying habitat quality and permeability that directly and indirectly influence the effectiveness of natural areas for wildlife conservation. To assess how isolation and degradation of protected natural areas may affect long-term conservation efforts across the range of a sensitive subspecies, we used multiscale occupancy analysis, species distribution modeling, and circuit theory to identify hotspot areas of occurrence and potential landscape connectivity among areas of high quality habitat within and between protected natural areas. Big Cypress fox squirrels (Sciurus niger avicennia: BCFS) are state-threatened subspecies of fox squirrel endemic to forested wetlands in southwest Florida, which have been highly altered by human activities. Probability of occupancy of BCFS among conservation areas varied widely due to differences in environmental features (Hedge's g = 1.4705, 95% CI: 1.074–1.763). Fine-scale features indicative of habitat degradation, such as increasing midstory vegetation cover and decreasing bromeliad cover, negatively influenced BCFS occurrence. Home-range-level tree canopy cover differentially affected probability of occupancy dependent on proximity to urban areas. Additionally, home-range-level high summer temperature differentially affected probability of occupancy dependent on proximity to cypress domes. Habitat was distributed patchily both within and among conservation areas, separated by large areas of unsuitable vegetation communities and urbanized features that were barriers to movement. Considering the threat of increasing isolation of conservation areas due to continued development as well as current and impending degradation caused by land use and climate change within conservation area boundaries, we suggest a strong need for interagency coordination to improve, maintain, and acquire rights for protection of additional remaining habitat.

Additional Information

Conservation Science and Practice

Date of publication:

2021

Topics

small mammal

Research Categories

Disturbance Ecology Spatial Ecology Threatened and Endangered Species

Circuit theory to estimate natal dispersal routes and functional landscape connectivity for an endangered small mammal.

thackerk1 — Tue, 23 Jul 2019 23:06:39 +0000

Authors

Melissa J. Merrick

John L. Koprowski

Context Natal dispersal links population dynamics to landscape connectivity. Understanding how organisms perceive barriers to movement, or landscape resistance, during natal dispersal is important to conserve and manage populations threatened by fragmentation and habitat loss.

Objectives We aimed to (1) model probability of landscape use by an endangered small mammal (Tamiasciurus hudsonicus grahamensis) in the Pinaleño Mountains, Arizona, USA as a function of forest structure at the population and intra-population level, (2) identify potential natal dispersal pathways between natal and settlement locations based on landscape resistance scenarios, and (3) assess which resistance surface best represented observed exploration, disper- sal, and settlement.

Methods We modeled probability of habitat use via used and available animal locations. We developed three landscape resistance scenarios to represent individual differences in perceived resistance. We used circuit theory to identify potential long-distance dispersal pathways and to assess which resistance scenario best represented observed forest use and settlement.

Results Top probability of forest use models included physical landscape features, forest structure, and burn severity. Composite connectivity models, created from multiple resistance scenarios, identified areas that may promote long distance dispersal move- ments. Connectivity models developed from only natal focal nodes allowed for assessment of resistance scenarios; a non-linear, negative-exponential relationship between probability of use and resistance best represented observed exploration and settlement. Conclusions Circuit theory is a useful tool to identify potential small mammal movement pathways when high temporal resolution movement data are limited, and for assessing how well resistance scenarios represent observed settlement patterns.

Additional Information

Landscape Ecology

Date of publication:

2017

Topics

Arizona

Pinaleño Mountains

point selection function

small mammal

resistance surface

circuitscape

Research Categories

Disturbance Ecology Sky Islands Spatial Ecology Threatened and Endangered Species

Female-biased sexual size dimorphism: ontogeny, seasonality, and fecundity of the cliff chipmunk (Tamias dorsalis)

thackerk1 — Mon, 22 Jul 2019 21:28:06 +0000

Authors

Allyssa L. Kilanowski

John L. Koprowski

Female-biased sexual dimorphism is uncommon in mammals and is usually attributed to increased fecundity of large females. Moreover, sexual dimorphism is usually described for adults, and the ontogeny of sex differences is poorly documented. We studied cliff chipmunks (Tamias dorsalis), a small mammal with female-biased sexual dimorphism, to describe development of sexual dimorphism in juveniles and to measure sexual dimorphism and seasonal body mass in adults. To test the fecundity hypothesis, we compared body mass of females to litter size and body mass of offspring. Juveniles were not sexually dimorphic at emergence from the nest and did not differ in body mass 2 months after emergence. Adult chipmunks maintained a relatively stable body mass in March–October with females consistently larger than males. Maternal mass did not have an effect on litter size or mass of juveniles. Because females were consistently larger than males, the ontogeny of sexual dimorphism may provide insights into selection pressures that lead to female-biased sexual dimorphism.

Additional Information

Journal of Mammalogy

Date of publication:

2016

Topics

body mass

cliff chipmunk

litter size

small mammal

female-biased sexual dimorphism

Arizona

Research Categories

Natural History Population Ecology Sky Islands