Shrike predation on the lizard Mesalina adramitana in Qatar ; a review of reported reptile and amphibian prey

ABSTRACT We report, for the first time, evidence of predation by a shrike (Lanius sp.) on the lizard Mesalina adramitana. This is the first record of predation by shrikes on lizards in Qatar. Whilst we did not directly observe the event, the presence of shrikes in the area and the method of impalement indicate shrikes as the predator. The lizard was found freshly impaled on a palm tree (Phoenix dactylifera), at 150 cm above ground. Bird species of the genus Lanius are well-known predators of lizards, and in arid environments reptiles are likely common prey for these birds. We provide a review of literature concerning predatory events by shrikes on reptiles and amphibians. We suggest inspection of shrubs for animals impaled by shrikes can improve biodiversity inventories, complementing other commonly used methods.


INTRODUCTION
Passerine birds of the genus Lanius display a predatory behavior similar to that of raptors. 1 Since shrikes do not possess the strong talons necessary for tearing small pieces from larger prey items, present in raptors, they have overcome this limitation by developing impaling behavior, using sharp objects, such as barbed wire, cacti, thorns and yucca 1 -6 .Impaling has several main functions: (i) to completely kill otherwise still living prey; 7 (ii) to serve as a food storage strategy; 8 (iii) to facilitate feeding on the impaled prey, thus compensating for the lack of talons; (iv) as advertisement, both of territory ownership to conspecifics and of male quality to female shrikes. 6Birds belonging to the genus Lanius comprise 29 extant species worldwide. 9Shrikes are reported to prey mainly on invertebrates, but also on a wide variety of vertebrates: 6 amphibians and reptiles, 10 birds and mammals, 11 including bats. 12The importance of vertebrates as prey for shrikes varies largely according to the study.For example, for L. collurio, a migrant shrike species present in Qatar in late spring and early autumn, 13 the proportion varied between 0-5% 14 -18 , to 22% in a recent study in Italy where reptiles represented 12.5% of the observed prey. 19Bigger shrike species, like L. meridionalis, the only resident shrike in Qatar, 13 hunts larger proportions of vertebrates. 16Predation of shrikes on some reptile species contributes to shaping morphological adaptations against predation.Thus, Young et al. 20 showed that loggerhead shrikes (L.ludovicianus) prey on flat-tailed horned lizard (Phrynosoma mcallii) with relatively shorter horns and that this source of mortality produces directional selection,  L. sp.

Phoenix dactylifera
Present study favoring longer horns.The intensity of bird predation was shown to impact reptile communities by inducing changes in lizard parasites. 21

OBSERVATION
During 2012 -2013 a preliminary field inventory of lizards was carried out in Qatar, resulting in a list of 21 species. 22On April 12, 2013 at 11:50 am we observed a still alive, adult male Mesalina adramitana freshly impaled on a palm tree (Phoenix dactylifera), at approximately 150 cm above ground, near Al Jassasiya (N25.9627,E51.3914) (Figure 1b).The palm tree had a height of approximately 3.5 m and was the only tree in a radius of several hundred meters (Figure 1a).Several passeriform birds, including an unidentified species of Lanius were seen in nearby shrubs.Whilst we did not directly observe the predation event, the presence of shrikes in the area and the method of impalement indicate shrikes as the predator.In this note we add Mesalina adramitana to the reptile species list preyed on by shrikes that to our knowledge was not yet reported.Other species present in Qatar have been photographed as shrike prey in other countries, such as Acanthodactylus schmidti in Dubai 23 and Cyrtopodion scabrum in Kuwait. 24Although usually thorny shrubs or trees are used as larders by shrikes, in xeric areas in Algeria shrikes have been reported to use palms as food storage, 25 similar to this observation in Qatar.This is the first report, to our knowledge, of the predation of shrikes on lizards in Qatar.Predation of shrikes on amphibians and reptiles were reported generally in North America and Europe.Reptiles are frequently reported as shrike prey in arid environments, including a variety of lizards, snakes and even occasionally tortoises 12,19,26 .Clark 7 gives a list of reptiles and amphibians reported in the literature as prey of the Loggerhead Shrike (L.ludovicianus), but did not provide details regarding the support used for impaling.We compiled a more detailed list of amphibian and reptile prey species of shrikes, not limited to a country or species (Table 1).

DISCUSSION
During our surveys, the impaled specimen was our first sighting of M. adramitana in Qatar, and this observation compelled continued searching for the species in that area.In a similar way, rare and elusive skinks were identified or studied: Chalcides simonyi was detected from scattered body parts in a kestrel pellet and impaled specimens by shrikes in the Canary Islands. 27During several reptile samplings in Socotra Island, Trachylepis socotrana was detected, but only impaled as shrike prey. 28hus searching for animals captured and impaled by shrikes can prove useful especially when dealing with rare and elusive species, complementing commonly used methods for species inventory in biodiversity studies.In a similar way rodent inventories are often improved by analyzing regurgitated pellets or scats of predators such as the barn owl (Tyto alba) 29,30 or genet (Genetta genetta). 30

CONCLUSION
Additional biodiversity inventories will allow the estimation of the importance of shrike predation on vulnerable lizard communities in Qatar.These inventories are necessary to complete preliminary distribution maps of lizards in Qatar, 22 and should consider detailed observations of vegetation and thorns, as well as examination of excrement and pellets from avian and mammal predators.

Table 1 .
Reported predation events of Lanius species on amphibians and reptiles.Information not provided in the literature is indicated by n.a.