Abstract
We investigated the feeding ecology of the crested porcupine Hystrix cristata in a semi-arid area of its northwestern Algerian native range over 8 months (September to April). Our results from micro-histological analysis based on faecal pellets revealed that this strict herbivore ate only 10 plant species, 8 wild and 2 cultivated, belonging to 9 families including Lamiaceae, Palmaceae, Poaceae, Ramnaceae and Fabaceae. The autumn diet was dominated by Thymus algeriensis, Ziziphus lotus, Chamaerops humilis and Triticum aestivum, the winter diet by T. algeriensis and C. humilis, and the spring diet by Muscari comosum, with a large amount of Vicia faba and T. aestivum. We confirm the role of this rodent species as a generalist herbivore which barely feeds on cultivated plants when wild resources are diverse and abundant.
Introduction
While the crested porcupine, Hystrix cristata Linnaeus, 1758, is expanding in Italy (including Sicily and more recently Sardinia) where it was introduced (Amori & Angelici 1992, Capizzi & Santini 2008, Masseti et al. 2010, Mori et al. 2013), populations are scattered within its native African range (Happold 2013), are declining in Northern Africa (e.g. in Morocco, Aulagnier et al. 2017) and is probably already extinct in Egypt (Osborn & Helmy 1980). The species is intensively poached in the Northwestern part of its range for meat consumption, traditional medicine, and sorcery practices (Aulagnier et al. 2017). Moreover, and besides its important influence on landscape through both biotic (plant dispersal) and abiotic (water percolation and soil turnover) impacts (Gutterman, 1982, Lovegrove & Jarvis 1986, Dean & Milton 1991, Bragg et al. 2005), it is broadly considered a pest for agriculture due to its intense digging activity. The European Habitat Directive mandates the protection of the crested porcupine (Clavero 2014) as well as the compensation for crop damages in agricultural fields (e.g. Italy; Laurenzi et al. 2016, Lovari et al. 2017). Indeed, as a generalist herbivore, crops occur in most droppings of crested porcupine living near agricultural areas (Pigozzi & Patterson 1990, Zavalloni & Castellucci 1994). Seasonal variations of the diet have been reported, with selection of roots and rhizomes, and avoidance of bulbs and tubers in winter and spring; and selection of bulbs, tubers and fruits, and avoidance of vegetables in autumn (Lovari et al. 2017). Additionally, Mori et al. (2021) recorded the anecdotal consumption of insects in early spring.
The porcupine's diet has been poorly studied in its original range, spanning formerly from Morocco to Egypt, and from Senegal to northern Tanzania (Happold 2013). with the principal food items being fruits, roots, bulbs and bark, cassava, sweet potatoes and groundnuts (Happold 2013). In Niger, the consumption of two shrub species, Calotropis procera and Merua crassifolia, involves deep digging to access roots. Furthermore, local diet includes also lizards and grasshoppers (Dragesco-Joffé 1993). Some food preferences have been recently reported from arid south-eastern Tunisia (Ettiss et al. 2020) where porcupine feed more on wild than on cultivated plants, mainly Poaceae: Stipa lagascae, Hedysarum carnosum and Hordeum marinum. In Misurata, Libyan inhabitants mentioned that crested porcupines cause a great damage to cultivated crops (Mohamed 2011).
In Algeria, the crested porcupine lives in forests, maquis, steppes and arid rocky terrains, but not in the desert (De Smet 1989, Kowalski & Rzebik-Kowalska 1991). It is still common in the coastal zone or in high altitude plateaus where damage to crops can be locally high (Bounaceur, pers. obs.). Constant farmer complains encouraged us to investigate the diet of crested porcupine in the Algerian plateaus, where the natural vegetation is poor and the landscape is dominated by crop fields (Habib et al. 2020).
Here we aim at investigating the consumption and a possible food preference of cultivated versus wild plants of a crested porcupine family over 8 months inhabiting a semi-arid Mediterranean area in North Africa. This is the first study of its kind in Northern Africa that we are aware of. Due to a higher energetic value, we hypothesized that porcupines (1) would mostly feed on cultivated plants when they are seasonally available; and (2) (would specialize on few plant species when resource levels are high Belovsky (1978).
Material and methods
The study site is located in a semi-arid Mediterranean land named “Dhaya” (35°35′45.4″N, 1°43′07.3″E) 5 km northwest of Tissemsilt, 250 km southwest of Algiers and 170 km from the Mediterranean Sea (Fig. 1). Annual rainfall varies from 350 to 500 mm, occurring mainly during winter and spring. The summer is dry and hot (mean temperature 20 °C. with a maximum of 35 °C). This region of hills and plateaus has been devoted to agriculture for more than one century with crop fields and vegetable products covering about 80% of the area (Bounaceur, pers. obs.). The main cultivated plants are wheat (Triticum aestivum), beans (Vicia faba), peas (Pisum sativum) and lentils (Lens culinaris). The wild vegetation is dominated by Chamaerops humilis, Thymus algeriensis, Atractylis humilis, Asphodelus microcarpus, Ziziphus lotus; additional local plants are Muscari comosum, Carduncellus pinnatus, Eryngium planum, Atractylis caespitosa, Thapsia garganica and Thymelea hirsuta.
The diet of Hystrix cristata was studied by micro-histological analysis of faeces collected during the first week of each month (i.e. sampling event) from September 2015 to April 2016 (period when animals were present). This non-invasive method is based on the specific identification of animal remains and plant fragments (cuticles) in the faeces (Butet 1987). During each sampling event 5 to 10 fresh crested porcupine pellets, easily distinguishable by morphology (see Barthelmess 2006), were collected around a single den, an underground cavity within a crop field, sheltering two adults and two sub adults that were opportunistically observed. Pellets were air-dried and stored in paper bags (Benamor et al. 2019, 2021). Based on the work of García-Gonzalez (1983), we prepared reference slides of epidermis of the main plant species growing in a 3 km area around the den as we suspect porcupines mostly use the area inside such circle (Mori et al., 2014). Preparation and identification of epidermis are described in detail in Lasgaa et al. (2021) and in supplementary material. Following Chapuis (1980) we identified the first 500 epidermal fragments for each sampling event by comparison with reference slides. No animal remain has been found.
The evaluation of plant abundance within the 3 km-radius area around the den was conducted in April 2016 – which is the month of maximum development of annual plants – following Lasgaa et al. (2021) (and supplementary material). The cover plant ratio (CR%) for each species was calculated as CR% = 100/1000 × Σn R(i) with R(i) = π d(i)2/4 of each plant species stem (i) at ground level with d: diameter of stem (Daget et al. 2010).
The diet of H. cristata was quantified by relative abundance (A%), calculated as: A% species i = Ni ×100/N, where, Ni is the number of epidermal cuticles of species i, N the total number of epidermal cuticles. We then compared the consumption of cultivated versus wild plants over the whole study period and the monthly consumption of cultivated plant species with chi-square tests.
Seasonal variations in the specific composition of the diet were analysed by a factorial correspondence analysis (FCA) calculated on the number of epidermal cuticles of each plant species. This was followed by a hierarchical classification on factorial co-ordinates using the Ward's grouping criterion in the PAST 1.37 software (Hammer et al. 2001).
Then we calculated the diet preference of crested porcupine in spring 2016 using Ivlev's electivity index which compares the relative abundance of the available food species in the environment and the choice of food consumed by the animal (Ivlev 1961). It is calculated here as: Ei = (A% – CR%)/(A% + CR%). This index varies from −1 to 0 for a negative selection and from 0 to +1 for a positive selection (Jacobs 1974).
Results
From the 75 collected pellets (4,000 plant fragments) we identified 10 plant species belonging to 9 families, with undetermined taxa accounting for less than 1% of epidermis fragments (Table 1). Overall the main plants consumed by this porcupine family were the wild Chamaerops humilis (A% = 29.60), mainly underground parts, and Thymus algeriensis (A% = 29.48), followed by Muscari comosum (A% = 7.70), the cultivated Triticum aestivum (A% = 7.65) and the wild Ziziphus lotus (A% = 6.50). Three species were not consumed despite being quite abundant around the den: Eryngium planum, Atractylis caespitosa and Thymelea hirsuta. On the contrary, several species were widely consumed despite being scarce: M. comosum, Thapsia garganica or Carduncellus pinnatus (Fig. 2). Overall, cultivated plants were significantly less consumed than wild plants (chi-square = 2342.3, df = 1, P < 0.001).
Monthly and total (A%) relative abundance, and minimum number of plant species in the diet of Hystrix cristata in a semi-arid area of northwestern Algeria
Species | Family | Sep | Oct | Nov | Dec | Jan | Feb | Mar | Apr | A% |
Asphodelus microcarpus | Liliaceae | 0 | 0 | 0 | 5.2 | 22.4 | 4.8 | 3.2 | 3.4 | 4.88 |
Atractylis humilis | Asteraceae | 4.0 | 0 | 0 | 4.2 | 3.8 | 6.0 | 3.6 | 3.8 | 3.18 |
Carduncellus pinnatus | Asteraceae | 0 | 0 | 0 | 0 | 0 | 4.0 | 13.2 | 13.6 | 3.85 |
Chamaerops humilis | Palmaceae | 11.6 | 38.4 | 51.0 | 31.4 | 49.0 | 20.6 | 18.0 | 16.8 | 29.60 |
Muscari comosum | Asparagaceae | 0 | 0 | 0 | 0 | 0 | 34.8 | 15.8 | 11.0 | 7.70 |
Thapsia garganica | Apiaceae | 2.8 | 4.0 | 2.0 | 0 | 0 | 0 | 4.4 | 7.2 | 2.55 |
Thymus algeriensis | Lamiaceae | 23.6 | 28.8 | 45.2 | 57.6 | 24.8 | 26.0 | 18.6 | 11.2 | 29.48 |
Ziziphus lotus | Ramnaceae | 24.0 | 28.0 | 0 | 0 | 0 | 0 | 0 | 0 | 6.50 |
Wild | 66.0 | 99.2 | 98.2 | 98.4 | 100 | 96.2 | 76.8 | 67.0 | 87.73 | |
Triticum aestivum | Poaceae | 32.0 | 0 | 0 | 0 | 0 | 3.8 | 11.2 | 14.2 | 7.65 |
Vicia faba | Fabaceae | 0 | 0 | 0 | 0 | 0 | 0 | 12.0 | 18.8 | 3.85 |
Cultivated | 32.0 | 0 | 0 | 0 | 0 | 3.8 | 23.2 | 33.0 | 11.50 | |
Indeterminate taxa | 2 | 0.8 | 1.8 | 1.6 | 0 | 0 | 0 | 0 | 0.78 | |
Number of species | 7 | 5 | 3 | 4 | 5 | 5 | 8 | 10 | 10 |
The consumption of crop species varied significantly along the year (chi-square = 699.0, df = 7, P < 0.001), due to a deficit from October to February which is compensated by the wild Ziziphus lotus (October), Thymus algeriensis (November-December), Asphodelus microcarpus (January) and Muscari comosum (February).
The first axis of the factorial correspondence analysis (37.7% of variability) clearly separated a February – April (= spring) diet from the rest of the sampled months (Fig. 3), whereas the second axis (30.9% of variability) opposed September – October (= autumn) and November – January (= winter) diets. The spring diet was characterized by the consumption of Vicia faba, Carduncellus pinnatus and Muscari comosum. The autumn-winter diets were characterized by the absence of V. faba and partly Triticum aestivum, which is mainly compensated by a high intake of Chamaerops humilis and Thymus algeriensis. The autumn diet was associated with Z. lotus while the winter diet was associated with a higher consumption of A. microcarpus and C. humilis.
For summarizing, we recorded the highest diversity of plant species in the diet in March and April, and the lowest diversity in November (Table 1). Moreover, according to the electivity index (Fig. 2), in April H. cristata selected mostly wild plant species within a relatively large array of available species. Among the selected plant species, the least selected was C. humilis. Except V. faba which is selected, the cultivated plant species are avoided, either T. aestivum, or almost Hordeum vulgare and Triticum durum.
Discussion
Diet composition
Faecal analyses in an Algerian semi-arid area support that Hystrix cristata is a mostly vegetarian species as, contrary to Mori et al. (2021), we did not detect insects in the faecal samples we analysed. We identified only 10 plant species in the diet, which is less than the 17 and 18 species recorded in Italy and Tunisia, respectively (Ettiss et al. 2020, Santini 1980). Such low diet diversity probably derives from to the small number and abundance of available plant species in our study area. Interestingly, the diet described in our study area does not share any plant species with those of Tunisia (Ettiss et al. 2020), which shows a noteworthy adaptation to local vegetation, already reported through habitat use (Zavalloni & Castelucci 1994, Sonnino 1998, Lovari et al. 2013).
In our study area the crested porcupine fed mainly on natural plant species (87.73%) despite four cultivated plant species were available, at least in spring, of which only two were consumed (Triticum aestivum and Vicia faba). Similarly, in Tunisia the diet was dominated by 15 wild plant species and included only three cultivated ones (Solanum tuberosum, Hordeum vulgare and Ficus carica) representing 15.97% of items (Ettiss et al. 2020). In Libya, Mohamed (2011) reported the consumption of nine cultivated species but lacked quantitative analysis of the diet. In Italy, most studies focused on the impact of the rodent on agriculture and/or did not compare the amount of wild versus cultivated species in the diet (Santini, 1980, Pigozzi & Paterson 1990, Bruno & Riccardi 1995, Laurenzi et al. 2016).
Seasonal variations
Beyond the amount of cultivated plant species which availability is seasonal, our data support changes in the diet along the year with high monthly consumption of some species from Ziziphus lotus (September – October) to Carduncellus pinnatus (March – April) through Thymus algeriensis, Asphodelus microcarpus and Muscari comosum. In autumn and winter, the crested porcupine ate a lower number of wild plant species, with underground parts of Chamaerops humilis dominating the diet. In spring, the diversity of wild plant species in the diet increased together with the consumption of cultivated species. These seasonal variations are mostly explained by seasonal changes in vegetation and availability of inflorescences, fruits and seeds. Accordingly, Bruno & Riccardi (1995) reported the highest amount of grass inflorescences in summer months, of fruits in October and November, of storage organs in winter months, and of herbs in spring months. In Lovari et al. (2017) the seasonal diet is slightly different with roots and rhizomes prevailing in spring and herbs in summer. In Tunisia, the crested porcupine compensates the lack of cultivated plants during the cold season with a higher consumption of Stipa spp. (Ettiss et al. 2020), suggesting that the diet composition is related to both availability and palatability factors.
Food selectivity
Contrary to Belovsky (1978) who suggested that herbivores would specialize when resource levels were high and generalize when they were low, our April data shows that crested porcupine ate the highest number of plant species when diversity and availability were high. Moreover, this rodent selected most of the plant species included in its diet, avoiding three cultivated species abundant at that season, and Ziziphus lotus, which is the main food in September, after the summer drought. Unsurprisingly, Chamaerops humilis is not the most preferred in April, whereas it is the main food in November and January. The higher palatability of stems and inflorescences of other plants exceed the richness of the underground parts of this species. Similarly, in Italy, although the crested porcupine has been confirmed as a generalist herbivore, adapted to dig underground storage organs, a strong preference for fruits and epigeal parts of plants was detected (Lovari et al. 2017). Such preference can stimulate porcupines to travel long distances to search for food (Mori et al. 2017). According to Hofmann (1989), food selectivity of herbivores is difficult to understand because it is linked not only to measurable data, such as nutritional value or palatability, but also to poorly known components of species behaviour.
Conclusion
Our first hypothesis that the crested porcupine would mostly feed on cultivated plants when they are seasonally available is partly supported by the micro-histological analysis of faecal pellets. Triticum aestivum and Vicia faba were indeed consumed in spring and summer but wild plant species were the main component of the diet every month. In this semi-arid environment H. cristata was a strict herbivore, able to exploit several plant species, exhibiting an opportunistic feeding behaviour in relation to food resource availability, but selective when resources were more diverse and abundant, disproving our second hypothesis. To understand selection patters, future analyses of the nutritional quality of the various species and parts consumed are encouraged. Porcupines are believed to impact cereal fields as a consequence of intense rooting activity when foraging in the search for hypogeal parts of plants (Santini 1980). Such behaviour, which should be further investigated, could possibly explain why the crested porcupine is still extensively poached in Algeria despite legal protection since 1975.
The present study is a preliminary contribution to the feeding habits of the crested porcupine in a main landform of North Africa. Even restricted to a unique den, our results provide interesting information to moderate the current opinion of its impact on cultivated plant species in a particular context. Further studies of the trophic ecology of porcupines in different areas and habitats are needed to adapt conservation to local constraints.
Acknowledgements
This study was supported by MESRS Project of university research-training PRFU (ex. CNEPRU) Number: D00L02UN380120200001. We appreciated the constructive comments by the three anonymous reviewers on an earlier draft of the paper.
Supplementary materials
Supplementary data to this article can be found online at https://doi.org/10.1556/1777.2024.00055.
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