Predatory Habits Research Articles

The killing of wild birds in research revisited: nature, numbers, speed and ethics

In a recent editorial in the journal The Condor, Walsberg (1994) raises some important issues concerning bureaucratic inefficiency of which most people are aware. He is especially concerned about what he claims is the inefficient way in which collecting permits are issued to those who want to study various aspects of avian biology. However, Walsberg's essay, that centres on the killing of wild birds in research (collecting is a synonym for killing; Bekoff 1993), contains assertions that need considerably more clarification, scrutiny and support before they can be used to make policy about how collecting permits are issued. There are many ethical issues that he glosses over which are directly related to animal welfare. For example, it is not clear how his comparison between predation rates and the number of birds killed by Cooper's Hawk (Accipiter cooperii) and the number of birds killed by scientists, supports Walsberg's argument that more streamlined permit processing is needed. On the one hand, Cooper's Hawks (and other non-human predators) are natural born killers who do not behave according to a code of ethics; they are not moral agents who are responsible for their actions. On the other hand, most scientists who kill birds are not natural born killers. It seems reasonable to assume that they are moral agents who are responsible for their actions (for discussion see Bekoff and Hettinger 1994). In my view, the comparison between the predatory habits of wild animals and the killing habits of humans does not lend any strong support to arguments that there should be more rapid permit processing.

New species ofMegaselia(Diptera: Phoridae) whose larvae live in fig syconia (Urticales: Moraceae), and adults prey on fig wasps (Hymenoptera: Agaonidae)

Megaselia dentata sp. nov., M. ficaria sp. nov., M. parvorata sp. nov., M. surophila sp. nov. and M. vorata sp. nov. are described from South Africa. M. dentata and M. parvorata are reported from Zambia also. The larvae develop in the fruits of figs (Ficus spp.). The adult females of M. vorata and M. parvorata, at least, prey upon adult fig wasps; by piercing in turn the cuticle of the head, the thorax and the abdomen and sucking out the contents. The sexual dimorphism in the proboscis of the fig flies correlates with the predatory habits of the females. Similar sexual dimorphisms in the proboscis are widespread in Phoridae, so it is predicted that predatory habits will be found to be widespread in the family.

The Survival-Reproduction Selection Equilibrium and Reversed Size Dimorphism in Raptors

A variety of avian taxa contain groups with 'reversed' (i.e. males smaller than females) sexual size dimorphism (Jehl and Murray 1986). Of all these taxa, its occurrence in the Falconiformes (hawks, eagles, falcons), the Strigiformes (owls) and the Stercorariidae (skuas) has received particular attention in the literature. These three independently evolved taxa have very different biologies but share predatory habits and, to a lesser degree, species in each show partial or complete sexual role specialization during breeding with males provisioning and females nest-tending. In other avian taxa reversed sexual dimorphism seems largely attributable to female-female competition for mates, but this explanation has seldom been applied to the hawks, owls and skuas (cf. Olsen and Olsen 1987). The diverse hypotheses that have been proposed (see reviews in Andersson and Norberg 1981, Mueller and Meyer 1985) are usually linked to the predatory nature of these birds. Many consider only a single selection pressure, operating only on one sex, without considering opposing selective forces. Arak (1988) has criticized this approach, pointing out that sexual dimorphism must arise from selection pressures for and against changes in body size acting differently on the two sexes (Ralls 1976, Price 1984). In this paper we use the framework for the evolution of sexual size dimorphism set out by Arak (1988) in an attempt to identify how different selection pressures acting on the two sexes could have resulted in the evolution of reversed sexual dimorphism in hawks, owls and skuas. We do not attempt a comprehensive review. Rather, we hope to convince the reader of the usefulness of Arak's approach: it easily accommodates the existing hypotheses, but helps make them more comprehensive, and it aids in identifying testable predictions not previously evident. We also modify and extend an existing hypothesis and show how, when used in the context laid out here, it provides explanations for broad patterns, as well as some of the exceptions, of sexual dimorphism in the groups considered. Hypothesis for reversed sexual dimorphism in predatory birds can be sorted into three categories, based on an evolutionary increase in female size, a decrease in male size, or a divergence in male and female size. The 'large female' hypotheses are (using the terminology in Andersson and Norberg's (1981) Table 1): the anticannibalism hypothesis, the male subordination hypothesis, the pair formation hypothesis, the egg size hypothesis, the incubation efficiency hypothesis, the nest protection hypothesis, the follicle protection hypothesis, and the starvation hypothesis. All these hypotheses assume that selection on breeding success favors large body size in females. In contrast, other hypotheses assume that the breeding success of pairs is enhanced when males are small. The 'small male', hypotheses are the energy savings hypothesis, the pyramid of prey hypothesis, the territorial defense hypothesis, and the courtship hypothesis. The 'dimorphic niche' hypotheses maintain that breeding pairs divergent in size are better able to exploit the prey base. They include the food competition and female supplementary feeding hypotheses. Descriptions of all these hypotheses, plus their sources, can be found in Andersson and Norberg (1981), with the exception of the starvation (see Lundberg 1986) and courtship (see Jehl and Murray 1986) hypotheses. Arak's (1988, see also Hedrick and Temeles 1989) framework for the evolution of sexual dimorphism considers natural selection acting on the survival and the reproductive consequences of body size. At the equilibrium body size in either sex, the fitness consequences of

Systematic revision of the neotropical ant genus Megalomyrmex Forel (Hymenoptera: Formicidae: Myrmicinae), with the description of thirteen new species

This revision includes comparative morphological analysis, biological data from various sources and a consideration of geographical distributions. The genus is considered to be a natural group, including 31 valid species, of which 13 are here described as new. The species are distributed in four groups, morphologically and behaviorally characterized; individual keys and distributional maps are given. All types were examined, except for that of M. bituberculatus (Fabricius, 1798), probably lost; the species is considered inquirenda. M. duckei Forel, 1912 and M. leoninus var. nasutus Forel, 1912 are considered junior synonyms of respectively, M. balzani Emery, 1894 and M. staudingeri Emery, 1890. The Modes tus group comprises medium sized species that occupy or dig cavities under logs or rocks. Colonies may be large and may have one to several true queens. Workers forage in groups on the ground of tropical and subtropical forests, recruiting nestmates toward large food items. In the Modestus group are described as new M. ayri, M. caete and M. cupecuara. The Leoninus group comprises larger species, the gamergates of which take over the reproductive function. Nests occupy cavities under logs, with no traces of architecture. Workers forage individually on the ground or on shrubs, tending membracid nymphs. New species in this group are M. acauna, M. cyendyra, M. pacova and M. timbira. Species of the Silvestrii group maintain apparent non-obligatory lestobiotic relations with several genera of Attini. They occupy secondary cavities of the nests of their fungus-growing hosts and always have monogynous colonies with true queens. New in this group are M. cuatiara, M. mondabora, M. piriana, M. poatan and M. tasyba. The Pusillus group includes the smallest species of the genus, which live in general in diffuse colonies in the litter of tropical and subtropical forests. Some species may have colonies either with gamergates or with true queens. The shape of the mandibles and the relatively large eyes suggest predatory habits. M. miri is the only new species in the group. Lectotypes and paralectotypes are designated for M. balzani, M. foreli, M. goeldii, M. iheringi, M. latreillei, M. leoninus, M. modestus, M. myops, M. pusillus and M. symmetochus.

Descrição da fêmea, genitália do macho e larva de Ocyptamos sativus (Curran, 1941) (Diptera: Syrphidae)

The female, male genital apparatus and larva of Ocyptamus sativus are described. A short report of the predatory habits of this species is made.

Phagodrilus gen.nov. (Lumbriculidae): systematics and biology of a predaceous oligochaete from western North America

The genus Phagodrilus (Lumbriculidae) is erected for Phagodrilus macnabi sp.nov., a predaceous worm with a paryngeo-esophageal region resembling that of Agriodrilus, a monotypic genus from Lake Baikal, often cited as a potential progenitor of the leeches. The pharynx or gizzard of Phagodrilus has the opposite dorsoventral orientation of its triangular section to that of Agriodrilus (apex dorsad in Phagodrilus, ventrad in Agriodrilus). While the latter appears closely related to Lamprodrilus in terms of its reproductive system, Phagodrilus resembles the Stylodrilus–Hrabea complex. These characteristics clearly indicate separate origins of the predatory habit and convergence of these two taxa, which suggests reexamination of the relationship between them and the leeches and branchiobdellids.

Título en español.

Se informan 31 especies de reduvíidos en Puerto Rico. De éstas, 12 son endémicas y 7 representan registros nuevos en la isla. Las especies están distribuidas en 7 subfamilias. Más de 20 de estas especies se han capturado en lámparas trampa. Se informa que, al menos, mientras buscan sus víctimas, Tagalis sp. y. Ghilianella varicornis pueden estar en el suelo y encontrárseles rebuscando con cuidado entre la hojarasca. No se encuentran en Puerto Rico las especies Ploiaria gundlachi y Ghilianella longula, tal como lo señaló Barber.

Arthropod Parasitoids and Predators of the Onion Maggot (Diptera: Anthomyiidae) in Southwestern Ontario

Miniature (1 m2) mass-rearing beds containing onion maggot, Delia antiqua (Meigen), were established during 1980 and 1981 at three commercial onion-growing fields and an experimental farm in southwestern Ontario to attract local parasites and predators. Onion maggot (OM) pupae from each of the three generations were collected from the beds before eclosion and allowed to complete development in the laboratory, enabling collection and identification of emerging parasitoids. Seven insect species (three staphylinid, four hymenopteran) were confirmed as parasitoids of OM, of which only Aphaereta pallipes (Say) and Aleochara bilineata (Gyllenhal) were significant mortality agents (parasitism rates up to 17 and 20.7%, respectively). Twenty carabid, 42 staphylinid, and 17 other (total 79) arthropod species of predatory habit were associated with OM in or near the miniature rearing beds. Twenty-one of the 79 species of mooted predators accepted OM eggs, larvae, or pupae as food under laboratory conditions. Diversity of arthropod predators and parasitoids was highest at the experimental farm at London (53 + 7 spp., respectively) > the three commercial onion-growing fields at Thedford (39 + 6) > Keswick (36 + 5) > Bradford (36 + 4).

Pelagic trilobites as an example of deducing the life habits of extinct arthropods

ABSTRACTThis paper reviews the methods which have been used to deduce the life habits of trilobites. The most reliable conclusions are those that satisfy three independent criteria of evidence: (1) functional morphology of the exoskeleton; (2) analogy with living arthropods; and (3) geological evidence, as from facies relationships, or palaeogeography. Pelagic trilobites are one of the better examples for life habit reconstruction. The Ordovician trilobites that were most probably pelagic are those with hypertrophied eyes—Telephinidae, Opipeuteridae, Bohemillidae and Cyclopygidae—which satisfy the threefold requirements for evidence.Opipeuter, Carolinites(and other telephinids) were probably epipelagic, whereas cyclopygids andBohemillawere likely to have been mesopelagic, living in exterior sites around the perimeter of Gondwana in the earlier Ordovician. These pelagics divide into two morphological groups: poorly streamlined, sluggish species somewhat like the living hyperiidParathemisto, and well-streamlined species which are larger, and are considered to have been fast and active swimmers, with predatory habits. The streamlining of this group has been demonstrated by experiment. Other trilobites may also have been pelagic, but the evidence is less complete:Irvingellaand its homeomorphs, andRemopleurides. Most Olenidae, however, which have been supposed to have been pelagic, were benthic forms inhabiting a specialised environment low in oxygen and possibly below the thermocline; only the leptoplastines may have been pelagic.It is also shown that there are cases where ventral terrace ridges did not function to grip sediment during filter feeding. This applies not only to pelagic trilobites, but also to benthic ones in which the width and disposition of the doublure renders engagement with the sediment unlikely.

Osteologia do sincrânio de Ceratophrys aurita (Raddi, 1823) (Anura, Leptodactylidae)

The syncranial osteology of Ceratophrys aurita, a largosized and characteristic anuran of southeastern Brazil, is described. The main osteological features and their resultant manifestations, as well as the exostosic dermal ornamentation and the specialized dentition clearly confirm this species as a terrestrial, fossorial and phragmotic type, with active predatory habits.

Two new aphrotenian larval types from Chile and Queensland, including Anaphrotenia lacustris n.gen., n.sp (Diptera: Chironomidae)

AbstractTwo as yet unknown larvae of the circum-Antarctic subfamily Aphroteniinae, one belonging to Paraphrotenia cf. excellens Brundin, the other representing the new genus and species Anaphrotenia lacustis, are described. While the other members of the subfamily are confined to mountain streams, the larva of anaphrotenia has been found in the littoral zone of a shallow subtropical lake on Fraser Island off the coast of Queensland. Besides some peculiar specializations this larva attracts interest because of the primitive construction of the head capsule where the genae ventrally are widely separated and the wide medial interspace is occupied by a longitudinal postmental plate that is not fused with the genal margins. In these respects the Anaphrotenia larva stands out as the most plesiomorphic chironomid larva as yet known; and it comes probably rather close to the larva of the dipteran ancestor. With its closed head capsule and specialized mouth parts the predatory Paraphrotenia larva appears much more apomorphic. But it retains several comparatively plesiomorphous characters, and among the predatory species of the chironomid larvae it represents a very remarkable type. In both genera the crop is developed as a diverticulum from the oesophagus. The presence of a special, sac-like grinding mill at the caudal end of the crop in both genera seems to be unique. — The paper ends with a discussion on a comparative basis of some aphrotenian larval characters and their anagenetic status. Special attention is paid to the mentum and the development of ventromental and dorsomental teeth within Chironomidae. Also discussed is the independent development of predatory habits and their combination with special morphological traits within different monophyletic groups. Of special interest is the comparatively late occurrence of such habits and corresponding morphological traits high up in the chironomid hierarchy within the Harnischia-group, a phenomenon that is believed to be a case of evolutionary reversal.

Preliminary Indications of the Status ofRhinacloa forticornisas a Pest of Sea Island Cotton in Barbados

Abstract The status of Rhinacloa forticornis Reuter, the brown mirid of Sea Island cotton in Barbados is discussed. Unsprayed cotton had higher sweepnet catches of mirids and had retained fewer fruiting forms than sprayed cotton. Photographs show the damage circumstantially attributed to R. forticornis in the match-head, flared square, flower bud, flower and boll stages; there is no leaf tattering. A field of unsprayed cotton matured very few bolls in the presence of large numbers of mirid although some of the Sea Island plants and wild cotton appeared to be resistant to mirid attack/damage. Early instars were definitely phytophagous, but the predatory habits of later stages reported elsewhere could not be confirmed. Early shedding delays crop formation and this should be prevented by spraying although control is usually obtained as a result of spraying against other pests.

Functional morphology of the fossula spongiosa in some reduviids (Insecta—Heteroptera—Reduviidae)

Legs of Reduviidae show modifications and specialised structures adapted for their predatory habits and efficient prey capture. The variable forelegs of these insects apparently reflect the correlation between the structure of the legs and the types of prey. The tibial pads or fossula spongiosa are a common feature in the forelegs or fore- and midlegs of most of subfamilies of Reduviidae. The functional morphology of the tibial pads of the forelegs of three insects,Haematorrhophus nigroviolaceus (Reuter),Pirates affinis Serville andTriatoma rubrofasciata (De Geer) has been studied. The oily substance produced by the cushion-like secretory tissue and the minute tenet hairs on them increase the ability to sustain static tension and enhance the gripping efficiency of the legs. Scanning electron micrographs reveal distinct morphological variations among the tibial pads. In addition to the shape and size of the organs, the number, structure and density of the tenet hairs on them markedly vary. The ability of the foretibial pad to sustain static tension on smooth and rough surfaces has been found to differ among the insects studied and this is remarkable in predatory insects.

Failure of the Red Imported Fire Ant 1 to Reduce Entomophagous Insect and Spider Abundance in a Cotton Agroecosystem 2

Large numbers of the red imported fire ant, Solenopsis invicta Buren, were unable to pauperize the predator arthropod fauna of a cotton field in east Texas. None of the 47 taxa sampled was significantly reduced as a result of S. invicta predation. Because of its predatory habits on boll weevils, Anthonomus grandis grandis Boheman and Heliothis spp., and its failure to simplify the predator fauna, S. invicta must be considered an important predator in cotton agroecosystems where it is abundant. The evidence suggests that S. invicta is a fairly specialized predator though probably a polyphagous scavenger.

Internal Anatomy of Dolania americana (Ephemeroptera: Behningiidae)1

Based on dissections of different aged larvae and adults, the anatomy and developmental changes of the central nervous system, tracheal system, digestive canal and Malpighian tubules, circulatory system, and gonads of Dolania americana are presented. The Malpighian tubules are the most plesiomorphic in the Ephemeroidea; affinities with other families of Ephemeroidea are evident in many characters, some with Potamanthidae and Ephemeridae and some with Palingeniidae and Polymitarcyidae. Derived conditions are found in the alimentary canal (a result of predatory habits) and in characters associated with the shortened head capsule. Ontogeny of the ovaries is unique within Ephemeroptera: only a single egg matures in an ovariole and some ovarioles disintegrate in older and mature larvae. This type of oogenesis results in extremely low fecundity.

Ectoparasites of wild carnivora of Indiana.

Ectoparasites and other associates were collected from 8 species of wild carnivores occurring in Indiana. Parasites occurring most often and in greatest abundance on the Gray Fox (Urocyon cinereomgenteus) were Suricatoecus quadraticeps, Cediopsylla simplex, Chaetopsylla lotoris, Androulelaps fahrenholzi, and Ixodes cookei; on the Red Fox (Vulpes vulpes): Ixodes cookei and C. simplex; on the Coyote (Canis latrans): Cediolisylla simplex; on the Raccoon (Procyon lotor): Trichodectes octomaculatus, Ctenocephalides felis, Orchopeas howardii, C. lotoris, A. fahrenholzi, Ixodes texanus, I. cookei, and Dermacentor variabilis; on the Mink (Mustela vison): Stachiella larseni, Lynxacarus nearcticus, A. fahrenholzi, Zibethacarus ondatrae, and I. cookei; on the Long-tailed Weasel (Mustela frenata): Neotrichodectes minutus, Lynxacarus mustelae, and L. nearcticus; on the Least Weasel (Mustela nivalis): Stachiella kingi; on the Striped Skunk (MePhitis mephitis): Neotricltodectes mephitidis, A. fahrenholzi, Hirstionyssus staffordi, and I. cookei; and on the Badger (Taxidea taxus): Neotrichodectes interuptofasciatus, I. cookei, D. variabilis, and H. staffordi. Some of these parasites are normally associated with the hosts whereas some appear to reflect the predatory habits of the hosts. A number of new host records are given.

Trophic activity of planktonic foraminifera

Few studies have been reported on the predatory habits of planktonic foraminifera or on their position in marine food webs. Planktonic foraminifera are large marine Sarcodina possessing a calcium carbonate shell (usually < 1 mm diam.) surrounded by a dense halo of rhizopodia that in some species may increase the cell diameter to 20 mm. Food organisms are snared by the sticky rhizopodia which entangle the prey and draw it into a dense layer of cytoplasm near the shell where digestion occurs (Anderson & Bé, 1976). Clearly species survival, their abundance, and their distribution in a region are deter-mined by the availability of food organisms, so that species that prey on a wide variety of organisms have greater survival advantage than those with a more restricted range of prey. Hence, many of the traditionally studied topics in foraminiferal research such as species abundance, survival time, geographical distribution and contribution to calcium carbonate sediments may be significantly determined by foraminiferal trophic activity. A clearer understanding of foraminiferal predation may help to explain ancient and modern assemblages of species and thus contribute to a more systematic interpretation of foraminiferal ecology.

Avian Extinctions in an Isolated Tropical Wet-Forest Preserve, Ecuador

Abstract The avifauna of a small forest island in lowland Ecuador was surveyed to detect recent extinctions. The 87-ha national forest, at Rio Palenque, has had serious declines in bird species numbers, even within the relatively short period of 1973-78. Among the 170 species of forest-dwelling birds, I found no recent records for 19 species, 25 had been last noted in 1975, and 15 presently have precariously low populations. Attributes of the species that had local extinctions included, in order of importance, large body size (predatory habits), general rarity (specialization), or declining populations throughout their range. Illegal hunting was related to the loss of two species at the preserve. The importance of large refuges is reaffirmed by this study.

Isometopinae (Hemiptera: Miridae) in Pennsylvania: Biology and Descriptions of Fifth Instars, with Observations of Predation on Obscure Scale

Four species of isometopine mirids were studied in central Pennsylvania during 1976–77: Corticoris pulchellus (Heidemann), C. signatus (Heidemann), Diphleps unica Bergroth, and Myiomma cixiiformis (Uhler). Descriptions, illustrations, and a key are provided for the last instars. Seasonal history of all species is given, and more detailed field and laboratory observations are presented for C. signatus and M. cixiiformis, which prey on obscure scale, Melanaspis obscura (Comstock), infesting trunks of pin oaks. Eggs of both species are deposited under old female scale covers, and overwintered eggs begin to hatch in mid-April. Adults begin to mature during late May-early June. M. cixiiformis (and also C. pulchellus and D. unica) is univoltine but C. signatus has a 2nd generation during mid-summer. In the laboratory nymphs and adults of both species probed female scales and fed by curving the proboscis under the covers. These observations of predation on scale insects and oviposition are the 1st documented habits of any North American isometopid. The Isometopinae are regarded as the most plesiomorphic mirid subfamily; if the predatory habit is also assumed to be plesiomorphic, then discovery of scale predation by 2 species supports placement of the isometopines as the sister group of all other Miridae.

Ethology and ecology of cichlid fishes of the genus Etroplus in Sri Lanka: preliminary findings

The Asian cichlid fishes, Etroplus maculatus (Bloch) and E. suratensis (Bloch) were observed in their natural habitat. Ecological and behavioral interactions of these species have not been previously reported. E. suratensis benefits from being cleaned by E. maculatus; it is doubtful the ingestion of parasites and fungi is of much direct benefit to E. maculatus. The advantage to E. maculatus is more likely the survival and reproductive success of adult E. suratensis which in turn provide eggs and eleutheroembryos for the egg-young predatory habit of E. maculatus. Predation is lessened by age-specific crypticity of E. suratensis. E. maculatus displays a unique behavior during its parental cycle where both parents actively defend their young until they are nearly sexually mature and almost the size of the parents. Adult E. suratensis engage in altruistic multiple parental care where several adults care for a single brood that presumably were spawned by only two of the adults. Such behavior has not been reported previously for fish.