Interspecific competition between native Eurasian red squirrels and alien grey squirrels: does resource partitioning occur?

The gastropod shell influences important aspects of the hermit crab's life; however, the shells are commonly a limited resource. Therefore, different hermit crab species that coexist in intertidal areas are commonly involved in intraspecific and interspecific competition for shells. We assess if differences in shell preference, exploitation ability, or competition by interference can explain the partitioning of shells between the coexisting species Calcinus californiensis and Clibanarius albidigitus. Clibanarius preferred shells of Nerita funiculata among the six gastropod shells tested, while Calcinus did not establish a hierarchy in shell preference. Therefore, the preference for gastropod shell species does not seem to diminish the competition for shells in the wild. Clibanarius identified and attended to chemical cues signalling potential sites of available shells (chemical cues of dead gastropods); Calcinus did not respond to these cues (competition by exploitation). However, Calcinus was more successful in obtaining a new shell by interspecific shell fighting than Clibanarius. Consequently, the use of better quality shells (intact shells) by Calcinus in the wild can be explained by its greater fighting ability compared with Clibanarius. The bias in shell distributions through dominance by shell fighting, more than by exploitation ability, has also been suggested for other hermit crab species of these genera.

Download Full-text

The preference for yew (Taxus baccata) by a red (Sciurus vulgaris) only squirrel population

Wildlife Research ◽

10.1071/wr15009 ◽

2015 ◽

Vol 42 (5) ◽

pp. 426 ◽

Cited By ~ 3

Author(s):

Amy Haigh ◽

Ruth O'Riordan ◽

Fidelma Butler

Keyword(s):

Tree Species ◽

Tree Planting ◽

Taxus Baccata ◽

Grey Squirrel ◽

Red Squirrels ◽

Coniferous Species ◽

Coniferous Tree Species ◽

Term Maintenance ◽

Grey Squirrels

Context As invasive grey squirrels continue to spread, red only areas are becoming rarer. It has been reported that red squirrels can outcompete greys only in pure coniferous woodland. In areas of sympatry with grey squirrels, there are concerns about red squirrels’ dependence on certain coniferous tree species in light of recent tree diseases. Aims This study aimed to investigate tree selection by red squirrels in an area vulnerable to the spread of the grey squirrel, but currently free of this species. Methods During 2013–14, squirrels were trapped and monitored on a 315-ha managed island, with a woodland characterised by a mixture of deciduous and coniferous species. Radio-tracking revealed that squirrels clustered their activity along a network of yew trees, a preference they showed throughout the year. Trap success was also higher in traps placed on yew trees. Yew and beech were selected most commonly, but squirrels were also observed foraging on other items, such as sycamore flowers and lichen. Squirrels spent 35% of their time foraging, utilising the greatest number of tree species in June (n = 13). In spring, squirrels foraged to a greater extent on the ground than in the trees, and exploited a lower number of tree species. Conclusions There has been little previous data on the use of yew trees by red squirrels, but they have previously been listed as a species that is preferred by red squirrels rather than greys. This study has further emphasised the importance of this tree species to red squirrels. Implications The continued spread of the grey squirrel may lead to red squirrels becoming restricted to areas of intense management such as parks and, accordingly, optimum tree planting is required from the onset for the long-term maintenance of red squirrels. With recent concern about the disease vulnerability of other coniferous species, this study emphasises the relative importance of yew and other tree species in the distribution of red squirrels.

Download Full-text

Resource partitioning and interspecific competition in a tropical hermit crab community

Oecologia ◽

10.1007/bf00346266 ◽

1980 ◽

Vol 46 (3) ◽

pp. 365-379 ◽

Cited By ~ 53

Author(s):

Peter A. Abrams

Keyword(s):

Interspecific Competition ◽

Hermit Crab ◽

Resource Partitioning

Download Full-text

Interspecific competition between alien Pallas’s squirrels and Eurasian red squirrels reduces density of the native species

Biological Invasions ◽

10.1007/s10530-016-1310-3 ◽

2016 ◽

Vol 19 (2) ◽

pp. 723-735 ◽

Cited By ~ 7

Author(s):

Maria Vittoria Mazzamuto ◽

Francesco Bisi ◽

Lucas A. Wauters ◽

Damiano G. Preatoni ◽

Adriano Martinoli

Keyword(s):

Interspecific Competition ◽

Native Species ◽

Red Squirrels

Download Full-text

Natural strongholds for red squirrel conservation in Scotland

Nature Conservation ◽

10.3897/natureconservation.43.62864 ◽

2021 ◽

Vol 43 ◽

pp. 93-108

Author(s):

Andrew Slade ◽

Andy White ◽

Kenny Kortland ◽

Peter W. W. Lurz

Keyword(s):

Management Practice ◽

Management Policy ◽

Sciurus Carolinensis ◽

Red Squirrel ◽

Grey Squirrel ◽

Case Scenario ◽

Red Squirrels ◽

Worst Case ◽

Standard Management ◽

Grey Squirrels

The Eurasian Red Squirrel (Sciurus vulgaris) is under threat from the invasive North American eastern Grey Squirrel (Sciurus carolinensis) with 80% of the remaining red squirrel populations in the British Isles found in Scotland. In this study we develop a spatially explicit mathematical model of the red and grey squirrel system and use it to assess the population viability of red squirrels across Scotland. In particular, we aim to identify existing forests – natural strongholds for red squirrels – that can successfully support red squirrels under UK Forestry Standard management and protect them from potential disease-mediated competition from grey squirrels. Our model results indicate that if current levels of grey squirrel control, which restrict or reduce the distribution of grey squirrels, are continued then there will be large expanses of forests in northern Scotland that support viable red squirrel populations. Model results that represent (hypothetical) scenarios where grey squirrel control no longer occurred indicated that grey squirrel range expansion and the process of red squirrel replacement would be slow. Model results for an assumed worst-case scenario where grey squirrels have expanded to all regions in Scotland identified forest regions – denoted natural strongholds – that could currently support red squirrels under UK Forestry Standard management practice. The results will be used to inform forest management policy and support a strategic review of red squirrel management by land management agencies and other stakeholders.

Download Full-text