We review 147 incidents of the capture of small birds by mantids (order Mantodea, family Mantidae). This has been documented in 13 different countries, on all continents except Antarctica. We found records of predation on birds by 12 mantid species (in the genera Coptopteryx, Hierodula, Mantis, Miomantis, Polyspilota, Sphodromantis, Stagmatoptera, Stagmomantis, and Tenodera). Small birds in the orders Apodiformes and Passeriformes, representing 24 identified species from 14 families (Acanthizidae, Acrocephalidae, Certhiidae, Estrildidae, Maluridae, Meliphagidae, Muscicapidae, Nectariniidae, Parulidae, Phylloscopidae, Scotocercidae, Trochilidae, Tyrannidae, and Vireonidae), were found as prey. Most reports (>70% of observed incidents) are from the USA, where mantids have often been seen capturing hummingbirds attracted to food sources in gardens, i.e., hummingbird feeders or hummingbird-pollinated plants. The Ruby-throated Hummingbird (Archilochus colubris) was the species most frequently reported to be captured by mantids. Captures were reported also from Canada, Central America, and South America. In Africa, Asia, Australia, and Europe, we found 29 records of small passerine birds captured by mantids. Of the birds captured, 78% were killed and eaten by the mantids, 2% succeeded in escaping on their own, and 18% were freed by humans. In North America, native and non-native mantids were engaged in bird predation. Our compilation suggests that praying mantises frequently prey on hummingbirds in gardens in North America; therefore, we suggest caution in use of large-sized mantids, particularly non-native mantids, in gardens for insect pest control.
Praying mantises (order Mantodea, family Mantidae) are globally distributed predators that are mainly insectivorous; however, they can also subdue and consume vertebrates, as reported anecdotally from nature and from captivity, including small frogs, lizards, salamanders, newts, shrews, mice, snakes, tiny soft-shelled turtles, and even once a small bat (Teale 1953, Nash 1962, Johnson 1976, Ridpath 1977, Nickle and Harper 1981, Kevan 1985, Ehrmann 1992, Ehrmann and Schmidt 1992, Jehle et al. 1996, Tomasinelli 2000, Dale 2005, Costa-Pereira et al. 2010, Mebs et al. 2016). Although predation on birds by arthropods including mantises is well documented (e.g., McCormick and Polis 1982, Miller and Gass 1985, Brooks 2012), a synthesis focusing on mantises has not been published. Here, we compile and review records of predation on birds by mantises.
Several species of large mantids (Mantis religiosa, Tenodera angustipennis, Tenodera sinensis) were released across North America as biological control agents in the 1900s (Davis 1918, Bromley 1932, Gurney 1950, Vickery and Kevan 1983). These species have become established in the eastern USA, and they show mixed effects on arthropod community structure (Fagan et al. 2002). The introduced large mantids now constitute novel potential predators for hummingbirds and other small birds.
An extensive bibliographic search was conducted to locate all available published reports on bird predation and predation attempts by mantids using the Thomson-Reuters database, Scopus databases, SORA (Searchable Ornithological Research Archive), Google Scholar, Google Books, and ProQuest Dissertations and Theses. Social media were also searched. The following books not included in the large data-bases were hand-searched: Bedichek (1961), Russell (1961), Bridges and Guppy (1980), Toops (1992), True (1993), Ehrmann (2002), and Shackelford et al. (2009).
We found 147 reports of predation (or predation attempts) on birds by mantids, of which fewer than one third had previously been published (Tables 1–2). The remaining reports were found on social media sites (e.g., Hummingbird Society, Bird Watcher's Digest, National Geographic, Audubon Society, Discovery Channel, YouTube, etc.).
Our search produced 45 published accounts, 37 accounts from bloggers, three newspaper accounts, five published photos, 48 photos or videos uploaded to internet sources, and nine unpublished accounts (D. Bigas, pers. comm.). Of these predation events, 4% had been reported prior to the year 1920, 29% from 1920 to 1999, and 67% between 2000–2015. The rapid increase in the number of incidents reported since 2000 is most certainly because of the uploading of photos and media to the internet as well as the growing popularity of artificial feeding stations for hummingbirds. For 43 photos, North American hummingbirds and mantids were identified to the lowest taxon possible. Hummingbirds were identified by Remsen. Mantids were identified by Reinhard Ehrmann (Staatliches Museum für Naturkunde Karlsruhe, Germany), William F. Fagan (University of Maryland, College Park, USA), and Michael R. Maxwell (National University, La Jolla, CA, USA), using Helfer's (1987) key. Reinhard Ehrmann verified identifications of Mantis religiosa. One mantid in a photo from Panama (Figs. 2E–F) was identified by Reinhard Ehrmann, Julio Rivera (University of Toronto, Canada), and Henrique Miranda Rodrigues (Case Western Reserve University, Cleveland, OH, USA). Kai Schütte (University of Hamburg, Germany) identified a mantid to genus based on the shape of the pronotum in a photo in Vrydagh (1946). Bird taxonomy follows Dickinson and Remsen (2013) and Dickinson and Christidis (2014).
The 147 predation events involved 12 mantid species as predators, representing nine genera (Table 1). Birds captured were all in the orders Apodiformes and Passeriformes, and represented 24 identified species from 14 families (Table 2). The reported incidents originate from 13 different countries and from all continents except Antarctica (Table 1). The vast majority of cases originate from regions of warmer climate (<41° latitude). In the following, we summarize the documented incidents grouped by geographic region.
Reports from North and South America (n = 118)
Most reports (113 of 147) are from the USA (Tables 1–2), where 110 of 113 incidents were in gardens and yards, nature centers, bird sanctuaries, and state parks, where hummingbirds were attracted to feeders or flowers (Figs. 1, 2A–D). Hummingbirds captured included immatures and adults of both sexes. Incidents of hummingbird predation by mantids were reported for 26 states, with most incidents from New York, North Carolina, Texas, Arizona, and California.
In the eastern USA, the mantids engaged in bird predation preyed almost exclusively on the only breeding hummingbird species of that region, the Ruby-throated Hummingbird Archilochus colubris (e.g., Edwards 1934, Butler 1949, Hildebrand 1949, Murray 1958, Weingartner 1976, Conway 1992, Kesterson and Kesterson 1999). In the western USA, mantids captured a broader diversity of hummingbird species (Table 2).
Five cases of predation are reported outside of the USA (Tables 1–2): one in Canada, two in Central America, one in Trinidad, and one in Argentina. Four of these cases were mantids eating hummingbirds, and the remaining case was the mantid Coptopteryx argentina eating a White-crested Tyrannulet (Serpophaga subcristata) in Argentina (Burmeister 1864).
Reports from Australia and Asia (n = 9)
One predation event was reported for Asia (India), and 8 were reported for Australia (Tables 1–2). Morse (1922) encountered an unidentified mantid eating a “tiny naked” Yellow-rumped Thornbill (Acanthiza chrysorrhoa) near a bird nest in New South Wales. After finishing its meal, the mantid dropped the dead bird. Three other tiny unidentified birds were lying on the ground, each with a hole in its head through which its brains had been extracted, presumably by the same mantid. In the Northern Territory, Ridpath (1977) witnessed two incidents of a Brown Honeyeater (Lichmera indistincta) being captured by Hierodula werneri. In one instance, the captured bird was able to escape through its own efforts; in the second, the bird, held firmly by the mantid, was unable to escape until the human observer intervened (Ridpath 1977).
Reports from Europe and Africa (n = 20)
Four incidents were recorded for Africa, all involving the predation of small passerine birds by large mantids (Polyspilota aeruginosa, Miomantis sp., and Sphodromantis spp.; Tables 1–2). For Europe, all reports are from mantid attacks on living birds captured in mist-nets in Spain. Bigas et al. (2006) reported seven predation events, and nine additional events were relayed by D. Bigas (pers. comm.) during a multi-year banding project. Mantids (Mantis religiosa) entered the mist-nets to attack and eat entangled birds (Fig. 3A). Bigas et al. (2006) stated that the mantids were always large and heavy—most likely gravid females. Five species of birds were attacked (Tables 1–2). Bigas et al. (2006:237) described the feeding behavior of the mantids in the mist-nets:
“The modus operandi of the mantis seems to be to approach the bird, which is always hanging downwards, and then enter the cranial cavity via one of the eyes, feeding on the brain tissues. Although we have not seen the direct attack on the birds, we think that the mantis is most probably attacking the birds when they are still alive, rather than feeding on recently dead birds. We found several instances of the mantis feeding on the head of the bird, and on at least two occasions the mantis cut the head when it finished…. On the days when the attacks were noted, there were not any other losses in the ringing session caused by weather effects or by stress. In some cases the bird still had fresh blood on the head, which indicated a very recent attack and death….”
Mantid and Bird Species Involved
We found 147 cases of mantids preying upon small birds, involving nine genera in the Mantidae and 24 identified small bird species in the Apodiformes and Passeriformes. Not surprisingly, the mantid species tended to be relatively large, typically at least 6 cm in body length. Well-fed adult females of some of the larger genera in this study, such as Hierodula and Tenodera, can weigh up to 7 g (Ridpath 1977, Eisenberg et al. 1981). We note that 11 of the 24 reported bird species have masses <7 g; thus, mantids may frequently outweigh small birds and other vertebrates. Indeed, four mantid genera in the present study (Hierodula, Mantis, Stagmomantis, Tenodera) have been observed eating other small vertebrates, such as frogs, lizards, and mice (Rau and Rau 1913, Ridpath 1977, Vickery and Kevan 1983, Kevan 1985, Ramsay 1990, Ehrmann 1992, Ehrmann and Schmidt 1992, Jehle et al. 1996, Tomasinelli 2000, Mebs et al. 2016). As far as can be determined, all mantids engaged in bird predation were females. In two cases, mantid females were feeding on a bird while mating with a male mantid (e.g., Fig. 2C).
Most cases of bird capture were of hummingbirds (family Trochilidae) in North America and South America (114 of 147 total events). The weights of these hummingbird species ranged from 3–6 g, and so it is likely that almost all hummingbird species are vulnerable to predation by large mantises where they co-occur. Since mantids prey on small, vulnerable birds, one may wonder if they sometimes take nestlings. The only report of a mantis killing and eating apparent nestlings is the one by Morse (1922) from Australia relating to the Yellow-rumped Thornbill. Birds >6 g were captured in Australia, South Africa, Spain, and the USA, with some species up to 20 g. However, captures of larger bird species in Europe occurred when the birds were ensnared in mist-nets (e.g., Erithacus rubecula, Ficedula hypoleuca), which reduce the birds' defensive and escape abilities. Additionally, the birds' body mass was likely borne by the net, thereby allowing the mantids to feed on the heavier birds without actually holding them. Some large mantids, however, are capable of capturing larger birds outside of mist-nets. For example, Lauro (1976) reported that a mantid captured a Blue-headed Vireo (Vireo solitarius), a bird with a body mass of 14–19 g (Table 2). The mantid, holding the bird with a firm grip, was attempting to chew on the bird's wing, but the observers separated the mantis from the bird, which flew away apparently unharmed. Similarly, Ridpath (1977) reported the large mantid Hierodula werneri capturing a 25-g green treefrog (Litoria caerulea).
The preponderance of predation events of hummingbirds in North America can be explained by several factors. First, North America is inhabited by some of the world's smallest birds, hummingbirds, which can be overpowered by the larger mantid species in the genera Mantis, Tenodera, and Stagmomantis. Second, the popular practices of maintaining hummingbird feeders and planting nectar-rich “hummingbird plants” bring these birds close to humans, so that documenting their capture is more likely than for other bird groups. Third, the large mantids Mantis religiosa and Tenodera spp. were released across North America for biological control purposes in the 1900s (Davis 1918, Gurney 1950, Vickery and Kevan 1983). These mantids have become established and are relatively abundant in parts of the eastern half of the USA (Bromley 1932, Gurney 1950, Hurd 1999, Arnett 2000, Snyder and Evans 2006).
Mechanisms of Bird Capture by Mantids
Species within the order Mantodea, particularly those within the family Mantidae, are ambush predators (Svenson and Whiting 2004), including four genera in our compilation: Mantis, Sphodromantis, Stagmomantis, Tenodera (Svenson and Whiting 2004). When a bird comes within strike distance, usually 5–10 cm, the mantid quickly strikes with its two raptorial front legs, while holding to its perch with its four other legs (Fisher 1994, Schwetman 1995, Prete et al. 1999). Once the bird is seized, the mantid holds it firmly and begins to feed. Birds have been observed to die within one to a few minutes after capture (Dale 2005).
The majority of attacks resulted in the capture and eating of the birds (115 of 147 total attacks, including one case of some type of scavenging [see the following material]). Birds still alive when in the grasp of a mantid were usually trying to escape by vigorous wing beating accompanied by distress calls, but they were able to escape through their own efforts in only three attacks (Ridpath 1977; Anonymous 2009, 2010). In the remaining 26 cases, humans rescued the birds when alerted by the birds' distress calls or wing noise (e.g., Hildebrand 1949, Williams 1974, Lauro 1976, Mahler 1977, Dale 2005, Richman 2013). In one instance a Brown Creeper (Certhia americana) hanging defenseless in a mist-net was attacked by a mantid (Prescott 1968). Prescott (1968:59) noted:
The mantis had reached through the net mesh and firmly grasped the creeper who remained strangely motionless while the mantis fed on its right wing. The ulna was partially exposed and some flesh had been removed although there was very little bleeding along the approximately inch-long opening on the outer side of the wing.
After a while the insect ceased feeding, released the bird, and left the mist-net. The injured bird survived the attack and was later released by the banders. In two other cases, mantids injured birds hanging in mist-nets without killing them (D. Bigas, pers. comm.).
In about two-thirds of the cases, the birds were bitten in the head, neck, or throat (e.g., Carignan 1988, Kesterson and Kesterson 1999, Bigas et al. 2006, Lorenz 2007). In several cases, a hole was chewed in the victim's head through which its brains were extracted (Morse 1922; Bigas et al. 2006; K. Okamoto, pers. comm.). Direct observations of the capture event will be required to determine whether the mantises are programmed to attack the head and neck (rather than to just begin chewing the area closest to the mouth parts upon capture) and to quantify whether mantises have specific bird-handling techniques, and whether this varies among mantis species. Occasionally, birds were scalped or decapitated, and in a few cases they were defeathered by their captors (see Browne 1899, Dale 2005, Bigas et al. 2006, Shackelford et al. 2009).
One incident was a form of scavenging. An Anna's Hummingbird (Calypte anna) died after becoming impaled on barbed wire (Fig. 3B; M. Ralph, pers. comm.), and a female Stagmomantis limbata was then seen feeding on the carcass. Presumably, the bird was still moving after becoming impaled, because S. limbata does not attack non-moving items (MRM, pers. obs.), similar to other mantid species (Rau and Rau 1913).
Mantids as Food for Birds
Large mantises are themselves also eaten by birds. For example, in France, a praying mantis Mantis religiosa of 3 g weight was detected in the pellet of an Iberian Grey Shrike Lanius meridionalis (Lepley et al. 2004). Tergou et al. (2014) found 46 large mantises (including 41 Sphodromantis viridis, four Mantis religiosa, and 1 Iris oratoria) in the regurgitated pellets of the Tawny Owl Strix aluco in Algeria. In Australia, a Black-faced Cuckooshrike (Coracina novaehollandiae) was repeatedly seen catching and eating the large mantid Hierodula werneri (Ridpath 1977). In Singapore, a Hierodula sp., 6.5 cm in length, was found in the stomach of a White-breasted Kingfisher Halcyon smyrnensis (Gibson-Hill 1948). In Taiwan, the Besra Accipiter virgatus has been reported feeding its young with the large mantis Hierodula patellifera (Huang et al. 2006), and according to a Japanese study the oothecae of this same mantis species are often devoured by the Large-billed Crow Corvus macrorhynchos (Kurosawa et al. 2003). These examples of predation on large mantids are all by birds with >50 g body mass (see del Hoyo et al. 2016). Gurney (1950) listed 34 species of North American birds that feed on mantids of unknown sizes.
Some have suggested that North American hummingbirds might be largely immune to predation (Stiles 1978, Miller and Gass 1985, Hixon and Carpenter 1988, Zenzal et al. 2013). Nonetheless, in North America, a diverse array of vertebrate predators feed at least occasionally on hummingbirds, including raptors, other birds, frogs, lizards, snakes, and cats (Miller and Gass 1985, True 1993). However, reports on hummingbird predation in North America to date remain mostly anecdotal (Lockwood 1922, Lowery 1938, Norris-Elye 1944, Monroe 1957, Grant 1959, Wright 1962, Mayr 1966, Spofford 1976, Gamboa 1977, Hofslund 1977, Graves 1978, Seutin and Apanius 1995, Robinson 2003, García-C. and Zahawi 2006), and so the frequency of occurrence has yet to be quantified.
As for invertebrates, the main predators other than mantids on North American hummingbirds and other small birds are large orb-weaving spiders in the genera Nephila and Argiope (Kirkham 1925, Mackay 1929, Abbott 1931, Woods 1934, Stott 1951, McKenzie 1991, Graham 1997, Heck and Heck 2001, Sakai 2007, Martin and Platt 2011, Brooks 2012, Martínez-Sánchez et al. 2013). Brooks (2012) documented 69 incidents of bird capture by large orb-weaving spiders and found, as in our study, that hummingbirds were the most frequently captured birds and that Ruby-throated Hummingbirds were the most frequently reported victims. The diversity of bird species captured by spiders was more than twice that of the mantids (54 versus 24 bird species). Mantids took a higher percentage of small birds (>70% in the ≤6 g body mass range) compared to spiders (<50% in the ≤6 g body mass range; mean = 11 g). Both these trends make sense because the web-building spiders do not use their own body mass to subdue prey (see Nyffeler and Knörnschild 2013).
Analysis of photos from various parts of the USA that depict bird predation by mantids (see Methods section) shows that both introduced and native mantids kill birds (Figs. 1, 2A–D). Based on these records, 25 (58%) of the bird captures were by non-native mantids (Tenodera sinensis and Mantis religiosa), and 18 (42%) were by native mantids (Stagmomantis spp.). In the eastern USA, most incidents involved introduced mantis species, whereas native mantids usually were the predators in the western USA. Thus, bird predation by mantises in the USA is not solely because of the introduction of non-native mantid species; in fact observations of bird predation by mantids (Alexander 1888) predate the first record of a non-native mantid in North America.
For many years, the oothecae of non-native mantids have been released in gardens in the USA as a tool for controlling garden insect pests (Hurd 2008). However, the beneficial effect of these predators has been questioned (Antonelli and Glass 2004, Meyer 2010). A meta-analysis of predation by mantids on arthropod community structure reveals mixed effects (Fagan et al. 2002), with the addition of mantids enhancing arthropod herbivores in some cases (e.g., beetles and hemipteran bugs) while suppressing others (e.g., dipteran flies). Additionally, mantids feed on beneficial pollinating insects such as honey bees in addition to pests (Bromley 1948, Maxwell and Eitan 1998, Hurd 2008, Maxwell and Frinchaboy 2014). Also, non-native mantids engage in intraguild predation, i.e., predation on other predators such as native mantids and spiders, which may enhance pest densities (Hurd 2008). The spread of non-native mantids may even result in the loss of native species (Fea et al. 2013). At least one of the large non-native North American mantids (i.e., the Chinese mantis Tenodera sinensis) has since reached the status of an invasive species (Snyder and Evans 2006). These ecological considerations, together with the predation risk that mantids pose to some bird species, particularly hummingbirds, lead us to recommend caution in the release of mantids into North American gardens.
We thank the following for assistance in identifying mantids based on photos: R. Ehrmann, B. Fagan, J. Rivera, H. Miranda Rodrigues, and K. Schütte. D. Bigas graciously granted us access to his field notes. Peter E. Scott and an anonymous reviewer offered valuable criticisms. We thank the Western Australian Naturalists' Club for assistance in getting access to literature. Finally, we thank all those who gave permission to use their photos including ‘Dutch Birding' and ‘What's That Bug.'