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Acomys subspinosus 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Rodentia Muridae

Scientific Name: Acomys subspinosus (Waterhouse, 1838)
Common Name(s):
English Cape Spiny Mouse

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2017
Date Assessed: 2017-01-18
Assessor(s): Palmer, G., Midgley, J., Pence, G. & Avery, M.
Reviewer(s): Child, M.F.
Contributor(s): Avenant, N., Baxter, R., MacFadyen, D., Monadjem, A., Taylor, P. & Wilson, B.
Justification:
The Cape Spiny Mouse is listed as Least Concern because it is widespread in the Western Cape of South Africa with an estimated extent of occurrence (EOO) of 148,787 km². As this species mainly exists in rocky habitat unlikely to be transformed, there are suspected to be no major threats that could cause widespread population decline. Currently, although around 76% of the Western Cape is still considered natural or near-natural, information from the Western Cape Nature Conservation Board indicates that there is a continuing decline in natural habitat from agricultural expansion, especially on lower- to mid-slope areas (below 1,000 m) from planted pastures and rooibos, wine and fruit cultivation, which may impact the species in the future as climate change makes higher elevation habitats more suitable for agriculture. Additionally, there may be localised losses of habitat quality due to the spread of alien invasive species, inappropriate fire regimes (too frequent fires), and edge effects associated with agricultural and residential land-uses (for example, use of pesticides and predation from domestic pets). Although the species remains widespread and regularly encountered, proactive mitigation measures, including protected area expansion and habitat restoration, should be continued to counteract habitat loss.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is a true fynbos endemic (Breytenbach 1982), occurring in the Western Cape Province (Avery et al. 2005) and extending marginally into the Eastern and Northern Cape provinces (Avery and Avery 2011). Its range extends from Citrusdal in the west to Knysna in the east (Skinner and Chimimba 2005). It is generally associated with rocky habitats on mountain slopes, and thus can exist at high altitudes, but it also occurs in lowland fynbos habitats. No range shifts have been documented. Its EOO is estimated to be between 48,286 km² (using post-2000 records only) and 148,787 km² (using all records); EOO around the limits of its range (as shown on the distribution map) is 171,474 km². Its area of occupancy (AOO) is estimated to be 74,165 km² using all fynbos vegetation types within the EOO (Mucina and Rutherford 2006). The current amount of untransformed fynbos will be lower than this estimate but will still be above the 2,000 km² threshold for criterion B2.
Countries occurrence:
Native:
South Africa (Eastern Cape Province, Northern Cape Province, Western Cape)
Additional data:
Estimated area of occupancy (AOO) - km2:74165
Upper elevation limit (metres):1000
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species is widespread but not abundant. It is never trapped in high numbers at a site (J. Midgley unpubl. data) and it is never the dominant species in an area (Avery et al. 2005). Although direct population estimates and trends are not available for this species, we suspect a declining population based on ongoing habitat loss from agricultural expansion in the Western Cape Province (Pence 2014), which may be exacerbated by the current trend of planted pastures and rooibos, wine and fruit cultivation expanding onto lower- and mid-slopes below 1,000 m asl (Pence 2014). However, given that the core rocky habitats of the species are likely to be left untransformed and that habitat continues to be protected—between 2007 and 2014, 775 km² were added to the conservation estate of Western Cape Province (Pence 2014)—the net effect on population trend is unknown and thus assumed to be stable. Provided the current protected area network persists this species should not decline. Further research should test this assumption at sites from across the province.
Current Population Trend:Stable
Additional data:
Continuing decline of mature individuals:Unknown
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This species is often, but not only, associated with rocky areas on mountain slopes in fynbos vegetation and is almost entirely dependent on fynbos that has all its functional components. It is widespread but poorly correlated with vegetation structure (Bond et al. 1980), which may be due to its specific habitat compositional requirements, such as rodent-pollinated plants and plants with nuts. This species is thus generally not found in modified habitats. It appears to favour more mature fynbos where it can find seeds, particularly from restios (to which it is partial), but also takes green plant material, insects, millipedes and snails (Stuart and Stuart 2007). It changes its diet from primarily insects in winter and spring to mainly seeds in summer and autumn, which parallels a foraging behaviour shift from seed consumption to seed burial (Rusch et al. 2014). However, isotope analysis suggests their diet is stable for most of the year besides summer (van den Heuvel and Midgley 2014). It is nocturnal and thus a prey species for owls (Avery et al. 2005), and sometimes nests in holes rather than cracks and crevices (Breytenbach 1982). It seems to be an opportunistic breeder (Fleming and Nicolson 2002) and to disappear after fire before slowly recovering (van Hensbergen et al. 1992). It is absent from fire-breaks so is probably disadvantaged by frequent fires.
This species is also a keystone species as it scatter-hoards (by burying) seeds (Midgley and Anderson 2005) and pollinates flowers (for example, Letten and Midgley 2009; Turner et al. 2011). It may even be dependent on these resources. For instance, Fleming and Nicholson (2002) noted how breeding and population numbers depended on access to rodent-pollinated Protea humiflora. As up to 76% of seed caches contain just one seed, suggesting that scatter-hoarding may have evolved as an anti-pilfering strategy (Rusch et al. 2013), Cape Spiny Mice may help sustain landscape heterogeneity.
Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):1-2

Use and Trade [top]

Use and Trade:

This species is not known to be traded or utilised in any form.

Threats [top]

Major Threat(s): Although no major or specific threats are suspected to be impacting this species, habitat loss and degradation are suspected to be causing local declines. Habitat loss from agricultural expansion and urbanisation is suspected to have severely affected individuals existing in fringe habitats on low-lying fynbos areas; of the 24% that is severely degraded or entirely devoid of natural vegetation, about 14% is attributed to intensive agricultural land uses (Pence 2014).

The fynbos habitat is impacted in parts by invasive alien plants (IAPs) which, despite control efforts, are expanding (van Wilgen et al. 2012). Since the Cape Spiny Mouse feeds primarily on the seeds of restios (Skinner and Chimimba 2005), replacement of natural vegetation by non-indigenous species may impact the species and effectively reduce its area of occupancy. Similarly, altered fire regimes caused by synergies between IAPs and climate change may be or become a threat if the fire return interval becomes so short that seeds preferred by the Cape Spiny Mouse cannot be produced.

Conservation Actions [top]

Conservation Actions: The Cape Spiny Mouse has been recorded from virtually all protected areas in the Western Cape, including all eight components of the Cape Floral Region Protected Areas World Heritage Sites, which includes the Baviaanskloof in the Eastern Cape.

No specific interventions are necessary at this stage. However, protected area expansion and biodiversity stewardship schemes, especially to counteract the potential for vineyards to transform the mountain slopes where this species occurs, are encouraged. Progress is being made in protected area expansion in the Western Cape, especially in Critical Biodiversity Areas (CBAs) (Pence 2014). Stewardship on private lands may be particularly promising. For example, the Biodiversity Stewardship Programme has added over 490 km² to the Western Cape’s formal protected area network since its launch in 2003, by entering into biodiversity agreements with private landowners (Maree et al. 2015). Such agreements should be enhanced through best practice management techniques for both viticulture and biodiversity, a new field dubbed vinecology, which is actively implemented in South Africa (reviewed in Viers et al. 2013).

Ongoing clearing of IAPs and restoration of fynbos habitats will also likely benefit this species by creating habitat with indigenous restio species and thus food resources. 

Recommendations for land managers and practitioners: It is critical that the fight to eradicate IAPs from our protected areas continues and that every effort be made to maintain the “natural” fire regime within the fynbos. Landowners should be incentivised to employ the Working for Water programme (Department of Environmental Affairs) to restore habitats.

Research priorities: Rate of future habitat loss in the Western Cape, especially in higher altitude areas due to climate change and viticultural expansion; estimating population size through density estimates and total natural habitat available. This would enable a threshold of habitat loss to be calculated below which the population is expected to be fewer than 10,000 mature individuals; effectiveness of IAP removal in increasing Cape Spiny Mouse and small mammal occurrence and abundance; effectiveness of IAP removal in increasing Cape Spiny Mouse and small mammal occurrence and abundance; effectiveness of implementing vinecology management on Cape Spiny Mouse and other small mammals should be monitored and evaluated; research into how the Cape Spiny Mouse responds to fire frequency and the extent of dependence on nut-fruited plants and mammal-pollinated plants.

Encouraged citizen actions: Report sightings on virtual museum platforms (for example, iSpot and MammalMAP). As this species is easily distinguished by its spines, geo-referenced observations, especially from outside protected areas, will help to map distribution and habitat preference.

Citation: Palmer, G., Midgley, J., Pence, G. & Avery, M. 2017. Acomys subspinosus. The IUCN Red List of Threatened Species 2017: e.T275A110016981. . Downloaded on 18 December 2017.
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