Eberhard Curio

Ruhr University Bochum | RUB · Conservation Biology Unit

Stealing prey items from other animals entails obvious benefits for the thief. However, this so-called kleptoparasitic behavior can also involve costs including injury or even death, especially when stealing from a potential predator. Here, we examined how kleptoparasitic hover wasps (Parischnogaster sp.) that steal prey items out of spider webs ha...

Walden’s Hornbill, locally known as Dulungan or Talarak (Rh. waldeni Sharpe, 1877) is a Western Visayas endemic. Once found on Negros, Guimaras, and Panay, the species is now extinct on Guimaras and functionally extinct on Negros. The last viable population is confined to less than 10 percent of forest in the Central Panay Mountain Range. These pop...

Facultative ant–plant mutualisms are variable systems, shaped by a number of biotic and abiotic factors. Especially in tropical ecosystems, the generally assumed mutualistic benefits are often hard to prove. We studied the system Leea manillensis on the Philippine island Panay and its indirect defence mechanism against herbivory by producing extraf...

Background The Visayan Tarictic Hornbill (Penelopides panini) and the Walden’s Hornbill (Aceros waldeni) are two threatened hornbill species endemic to the western islands of the Visayas that constitute - between Luzon and Mindanao - the central island group of the Philippine archipelago. In order to evaluate their genetic diversity and to support...

Note on the museum label of ZMB 21773.

As is well known, many animals are able to orientate themselves in the earth's magnetic field. However, to date there is no evidence that squamate reptiles are able to perceive the earth's magnetic field. Here, we demonstrate the homing performance of the Philippine bent-toed gecko (Cyrtodactylus philippinicus Steindachner, 1867) after displacing i...

Great tit (Parus major) males, when confronted with a source of danger that is either classifiable or inclassifiable and close to their brood, mob more than females. By staying near the source of danger longer, by mobbing it longer and more vigorously, and by approaching it more closely, males incur a greater risk than females do and therefore, app...

We conducted an experiment to test whether great tits (Parus major) base their decisions of clutch defence on past investment or future benefits. Results were obtained by manipulation of future benefits. Great tit pairs of an experimental group with reduced clutch-size and thus diminished benefits defended their offspring against a live raptor sign...

1. Nahrungssuche und einige soziale Verhaltensweisen des Mangrovefinken von Albemarle werden beschrieben. 2. Wie der Spechtfink setzt der Mangrovefink ein Stöckchen ein, um im Holz verborgene Insekten hervorzustochern. Dieser Werkzeuggebrauch bestätigt die enge Verwandtschaft beider Finken und zeichnet sie vor allen anderen Geospizidae aus. Es ist...

The question was investigated whether an insectivorous bird when hungry can form the concept of bilateral symmetry which might enable it to detect resting prey proficiently. Eight great tits of both sexes were trained in four experiments with insects as reward to discriminate either between a pair of figures that differed only in terms of the prese...

Various experiments with 56 captive-born lizards, Anolis lineatopus, involving up to four replicates strongly suggest that the species is capable of olfaction. The readiness to attack four diverse prey species (cricket, Mediterranean flour moth, German cockroach, wood ant) was neither influenced by odour cues nor by the degree of novelty of the pre...

A new whip scorpion genus and species is described from Panay Island (Philippines) on the basis of three males and a female. The new genus is diagnosed from the superficially similar Thelyphonus by the structure of genitalia of both sexes.

Parental investment theory suggests that animals should increase their reproductive success by investing more heavily in higher-quality offspring than in lower-quality offspring. Great Tit Parus major nestlings of higher body weight have been shown to enjoy a higher survival rate after fledging. We examine for the first time whether Great Tit paren...

Tracking the dispersal of seeds by fruit-eating animals in tropical rain forests is crucial to further our understanding of plant–frugivore interactions and their impacts upon forest regeneration and plant population dynamics. We tested the feasibility of tracking bat-dispersed seeds in a Philippine lowland rain forest with the help of fluorescent...

Two Philippine hornbill species, the Visayan writhed-billed hornbill (Aceros waldeni) and the Visayan tarictic hornbill (Penelopides panini panini), display on their heads multiple sexual ornaments in both sexes. An account is given of the maturation of these ornaments, except for the hood on the hind neck, from the nestling stage through age 5year...

We investigated whether sexual imprinting on an artificial novel adornment in the Javanese Mannikin Lonchura leucogastroides, a monomorphic estrildid finch, can occur and might provide a mechanism for the evolution of novel traits. We introduced a red feather on the forehead as a novel adornment. Young were raised by parents which were both adorned...

Double-choice experiments with three adult males of the little golden-mantled flying fox, Pteropus pumilus, and ten adult greater musky fruit bats, Ptenochirus jagori (both Megachiroptera: Pteropodidae), demonstrate that they are able to discriminate accurately between an empty dish and a dish containing fruits of one of several species by odour al...

Given the ubiquitous fact that resources for preserving whole faunas are limited, prioritisation of areas is called for. The popularity of the complementarity approach for setting priorities derives from their representing the maximum number of species of a taxon with a minimum number of areas, e.g. islands in an archipelago like the Philippines. W...

Given the ubiquitous fact that resources for preserving whole faunas are limited, prioritisation of areas is called for. The popularity of the complementarity approach for setting priorities derives from their representing the maximum number of species of a taxon with a minimum number of areas, e.g. islands in an archipelago like the Philippines. W...

On how birds protect their eyes: division of labour between the upper lid, lower lid and the nictitating membrane Birds close their eyes during sleep in various taxon-specific ways. Either the lower lid moves up as in the majority of species including the Anseres, Accipitres, Falconiformes, Galli, Charadrioidea, Columbiformes, and Oscines; or the u...

Birds close their eyes during sleep in various taxon-specific ways. Either the lower lid moves up as in the majority of species including the Anseres, Accipitres. Falconiformes, Galli, Charadrioidea, Columbiformes, and Oscines; or the upper lid moves down (Psittaciformes, Trochili), or both lids close the eye as in Strigiformes and Caprimulgi. Such...

Summary Birds close their eyes during sleep in various taxon-specific ways. Either the lower lid moves up as in the majority of species including the Anseres, Accipitres, Falconiformes, Galli, Charadrioidea, Columbiformes, and Oscines; or the upper lid moves down (Psittaciformes, Trochili), or both lids close the eye as in Strigiformes and Caprimul...

We show that roost switching in the musky fruit bat, Ptenochirus jagori, is probably determined by the spatially changing availability of fruit resources. We investigated the roosting behavior and foraging movements of this frugivorous bat species in a Philippine lowland rainforest with the help of radiotelemecry. Five male and five female P. jagor...

Sexual imprinting is one of several known non-genetical, yet social factors which influence mate preferences and might play a role in the evolution of novel traits. We introduced a red bill as a novel trait in a monomorphic estrildid finch, the Javanese mannikin Lonchura leucogastroides. We established three different imprinting groups in which the...

We investigated if sexual imprinting on birds with a red artificial trait can influence female preference for mates bearing other novel, i.e. not-imprinted traits in male Javanese mannikins (Lonchura leucogastroides). We tested two groups of females in mate choice tests. One group of females was sexually imprinted on parent birds adorned with a red...

Monitoring of nests of the Visayan Tarictic Hornbill Penelopides panini panini on the Philippine island of Panay revealed thus far undescribed information on the breeding biology of this species. Females occupied nest holes in March–April, after which two or three eggs are laid. Although cooperative breeding is suspected for the genus, at two nests...

We assessed the potential effect of frugivore extinctions on forest regeneration in the North Negros Forest Reserve, a forest fragment that is one of the last remaining wet tropical rainforest ecosystems in the biogeographic region of the central Philippine Islands. We evaluated foraging observations of 19 species of birds, fruit bats, and other ma...

This paper provides a botanical inventory of a forest community in the North Negros Forest Re-serve that is disproportionately valuable from a conservation perspective. The forest fragment is one of the last remaining wet tropical rainforest ecosystems in the biogeographic region of the West Visayas and an important refuge for a large number of end...

We investigated the different roles of the sexes in the origination of novel traits in the sexually monomorphic Javanese mannikin Lonchura leucogastroides. We introduced a red feather as an evolutionarily novel trait in both sexes and tested their preferences for prospective mates with this trait. Males rejected females bearing the red feather and...

We report on some aspects of the breeding biology of the critically endangered Writhed-billed Hornbill (Aceros waldeni) on the island of Panay, Philippines. Observations were made at three nests during 1995–1997. Walling-in of the females commenced in the first week of March. One female remained incarcerated for 77 days, two of three broods complet...

Here we report on a newly discovered population of Bleeding-heart Pigeon (Gallicolumba sp.) on the Philippine island of Panay, West Visayas. There have been 7+ sight-records and one photographic documentation in two places (Lahang, Sibaliw) of the low-elevation forest of the northwest Panay peninsula (400 – 450 m a.s.l.) in 1997. Reports from local...

In 1993 and 1994 we determined the frequency of extrapair paternity in broods of great tits, Parus major using multilocus DNA fingerprinting. We found no instances of intraspecific brood parasitism, but 40% of broods (31/78) contained extrapair-fathered young and 83% of offspring (58/681) were xtrapair We identified the genetic fathers of 60% of th...

With the number of species and near-to-natural habitats rapidly dwindling, conservation has become an undebatable necessity. There have been some laudable, successful species conservation projects but there have also been many deplorable failures. The failures are exacerbated by limited funding. Conservationists depend on funding by national govern...

The Scarlet-collared FlowerpeckerDicaeum retrocinctum of the Philippine island of Mindoro has been sighted nine times on neighbouring Panay (1992) and twice on Negros (1993, 1994). The possibility that these new records and others in the recent past reflect changes in the Philippine biota due to the rampant destruction of forests deserves close att...

To understand the interaction of the many contextual variables that affect parental behavior a number of static optimality models have been developed. Among these the one by Lazarus and Inglis (1986) is the only one to specifically predict the magnitude of unshared parental investment (PI), i.e., of parental care that carries a cost to the parent a...

Though logically distinct, functional and causal questions are intertwined in numerous ways. This is exemplified in both the meaurement and the analysis of anti-predator behaviour of two songbird species. Two non-trivial problems of measurement may hamper any in-depth analysis. First, when confronting one and the same predator stimulus situation, s...

The extent of parental care should usually increase with the benefits expected in terms of reproductive success. In monogamous birds, parental care should therefore increase with brood size. Some recent studies failed to show such a relationship, and we wondered if this may be due to phenomena like extra-pair copulations and/or intraspecific brood...

A previous study (von Brockhusen‐Holzer & Curio 1990) had led to the major conclusion that prey‐naive Anolis lineatopus hatchlings differ in terms of a “hard‐wired” perceptual mechanism underlying the recognition of cricket prey. We reconsider here one result leading to that conclusion since it rested on negative evidence in one treatment group as...

In many altricial species including the great tit (Parus major) the intensity of brood defense against predators has been shown to increase with the age of the offspring. This effect has been ascribed amongst others to the young becoming more vulnerable as they age (vulnerability hypothesis). In a great tit population suffering heavy losses from br...

Among prey-naive Anolis lineatopus from Jamaica, individuals reject ants most commonly, crickets less commonly, and waxmoth larvae almost never. This study investigates the individual differences in the mechanism underlying prey perception in two of many ethotypes found, i.e., cricket-rejectors and cricket-acceptors. In one experiment artificially...

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The recent development of life history theory has led to an upsurge of interest in species-specific mortality patterns. Some recent findings on the geographic variation of avian mortality may help to bring more sharply into focus some fundamental issues of ageing (senescence). To say that a bird 'ages' is tantamount to saying that its likelihood of...

The novelty of an animal and its sustained interest in a bird's defendable resource have been surmised to elicit cautionary behaviour when no innate recognition of the potential adversary exists. To examine whether anyone or both of these features is used, a live Java Sparrow Padda oryzivora was presented near the nest of pairs of Great Tits Porus...

Predator mobbing by great tits, Parus major, was studied by manipulating two contextual variables: the proximity of danger to the nest hole (close versus far), and breeding condition (non-breeding versus nest building versus care of nestlings). In five experiments pitting these contextual variables against each other, great tits were presented with...

Many iteroparous animals delay full reproductive effort past the age of reproductive maturity. According to a life history model this delay is likely to be selected for when the costs of reproductive effort (eg parental care) are low and/or the number of reproductive episodes is high. Benefit increases as reproductive effort increases from its lowe...

Both animals and humans appear to commit the 'Concorde Fallacy': they seem to gear their investment into a vital task to their past investment, though ideally they should gear it to the net expected future benefits (= benefits minus costs to complete the task)(1,2). By uncoupling past investment from expected benefits, animals have been variously s...

The multidimensional defence behaviour of great tit Parus major parents when confronting a live pygmy owl Glaucidium passerinum at their nests was subjected to uni- and multivariate analyses; the owl is a predator of both adults and nestlings of hole-nesting birds. A life history model of parental anti-predator defence of a brood by an altricial pa...

In pairs or groups of birds it is more often the male than the female who invests more effort and/or risk in predator defence. In the great tit (Parus major) too, the male risks more in defending a brood of nestlings from a live pigmy, owl (Glaucidium perlatum) than does the female; this opportunistic raptor takes, apart from mammals, both adult an...

Examined how members of great tit pairs cooperate while defending their nestlings and themselves against predatory danger of 2 sorts (owl + mixed mobbing chorus; the latter only). Pair mates cooperate by confronting the danger jointly in 77.2% of cases tested. In pairs with only one mate cooperating it is more often the male (15.2%) than the female...

1. Two male great tits (Parus major) were trained to distinguish between sounds from two locations in an operant two alternative, forced choice procedure with positive reinforcement. 2. The angle between the two sound sources, as experienced from the position of the experimental subject, was varied. The angle at which the birds scored 65% correct r...

Auditory tuning curves of a small songbird, the great tit (Parus major), and of its principal avian predator, the European sparrowhawk (Accipiter nisus), were determined by an operant positive reinforcement conditioning procedure, using the method of constant stimuli. Thresholds were measured by the criterion of a 50% correct response and a d of 1....

The influence of the surroundings on the response of pairs of domesticated Zebra Finches to a live Pygmy Owl was assessed. When the test chamber was surrounded by non-transparent curtains, the birds responded neither to a live Starling nor to an Owl that were placed in separate cages 1 m from the Finches. When some of the curtains were opened and w...

Social facilitation of the female's mobbing response by the male was studied in pairs of domesticated Zebra Finches. The male of each pair was experimentally frightened with a live Starling. Then, the pair mates were placed in separate, adjacent cages. The Starling was presented only to the male which, as expected, became very excited. The female w...

We examined the extent to which parental investment, as measured by brood defence, is determined by life-historical selection in a shortlived bird, the great tit (Parus major). Pairs tending first (n=20) and second (n=21) broods in the same Scots pine woods in 1983 were used to test predictions of a cost/benefit model of brood defence based on the...

There is a deadly risk of mobbing at a predator (= approaching it, usually alarm calling at the same time), as evidenced by a long list of published and unpublished accounts of a fatal or nearly fatal outcome for the prey involved. We examined in four predator‐related danger situations (two raptors [ Strix aluco, Accipiter nisus ], a raptor [ Glauc...

and Summary We examined the extent to which parental investment, as measured by brood defence, is determined by selection via life history in a short‐lived bird, the great tit ( Parus major ). Great tit parents tending 1st and 2nd broods of the season were used to test five predictions of a cost/benefit model of brood defence based on the species a...

Two semi-quantitative predictions about the intensity of defence against a predator based on the associated costs and benefits as a function of predator species, were examined in great tits (Parus major) feeding nestlings. One premise was that defence behaviour is adaptive. Defence comprised of vocalizing and homing in on a live raptor near the nes...

The deficiency of young parent birds to mate and reproduce successfully has been conventionally explained with 'reproductive constraint', eg lack of experience. Both life history theory and the demonstration of increased mortality with age suggests that 'reproductive restraint' is equally tenable. Young breeders with high future prospects of breedi...

Great tits failed to increase their multidimensional anti-predator brood defense behaviour as a function of brood size. They were however capable of such an increase with age of young and other factors, thus ruling out behavioural constraints to inhibit brood size-related defense. It is argued that parents might be strained maximally regardless of...

Blue Tits Parus caeruleus vary their predator-avoidance behaviour in relation to the size of hawk models. A life-size model of a Sparrowhawk Accipiter nisus passing about 4 m over the Tits inhibits locomotion for up to 3 min, and elicits an alarm call, scolding, that has characteristics which make it audible over a long range. A small model mimicin...

Great tits (Parus major) tending nestlings reacted defensively to a live predator (Glaucidium perlatum; domestic cat) and the playback of a mixed species mobbing chorus, or to the latter alone. Defensive behaviour, mainly mobbing, reflected the risk taken and is assessed by five measures. Multivariate and contingency analyses revealed that at least...

Since the process of natural selection entails a comparison of phenotypes and choosing of the best, optimality theory appears appropriate to identify selection pressures. Optimality theory doesnot test whether an organism is designed optimally — it assumes it. The ingredients of a complete optimization model are outlined and two approaches are exem...

A life-size model of a sparrowhawk Accipiter nisus passing c.4 m over the tits inhibits locomotion for up to 3 min, and elicits an alarm call, scolding, that has characteristics which make it audible over a long range. A small model mimicking a sparrowhawk at a height of 60 m above the tits inhibits locomotion for a shorter time (<1 min). This mode...

Studies of the risk taken by great tit parents while defending their brood prompted us to computeFisher's reproductive value vt as a function of age, sex, breeding habitat, and number of broods per year (Fig. 1–3). Although marred by the speculative nature of some underlying assumptions the resulting vt curves are most accurate for any animal in te...

Taped conspecific and alien species mobbing calls suffice to transmit enemy recognition of a conditioned object CS to European blackbirds (Turdus merula), though their reinforcing effect is probably less than that of a real blackbird mobber. Blackbirds habituated to the CS learn to mob it in the latter case without impairment, but fail completely i...

On the basis of DNA analysis, Gamauf and Haring (2004) proposed that Barred Honey-buzzard Pernis celebensis be split into P. celebensis of Sulawesi, P. steerei steerei of Mindanao and adjacent islands and P. s. winkleri of Luzon and Polillo islands in the Philippines. Ferguson-Lees and Christie (2005) proposed the name Steere's Honey-buzzard for P....

There are at least ten suggested hypotheses for the function of mobbing predators by fish, birds, and mammals. Experiments with captive European black-birds support one of these-the "cultural transmission hypothesis." Perceiving a mobbing conspecific together with a novel, harmless bird induced blackbirds to mob the innocuous object. The mobbing re...

A distinction is made between fitness-enhancing aspects of a trait and selective forces that result in its optimization. Any functional explanation conceived to account for the occurrence of mobbing behavior must explain the benefits both for the initiator and for the birds joining it. Nine teleonomic hypotheses are proposed that permit predictions...

The "cultural transmission hypothesis" and the "alerting others hypothesis" of enemy recognition in birds were examined in mobbing experiments with captive blackbirds. Observer Ss learned to mob a novel nonraptorial bird more strongly as a consequence of witnessing another S mob strongly at the site of presentation. Strength of the observer's enhan...

Summary A captive-bred pair of sibling pied barbets (Tricholaema l. leucomelan), had its first egg laid at 218 days of age and successfully reared 2 young. After fledging, and prior to breeding the pair had killed a third sib, with which it had been living. — Another pair (parents of the former) responded on two occasions to a suitable trunk with i...

Summary A captive pair of pied barbets (Tricholaema l. leucomelan) regularly performed false copulations with the same repetition rate per bout and the identical accompanying duet as is typical of true copulations, the only difference being that cloacal contact did not occur. 10 months after its first brood, the pair was again allowed to excavate a...

The “Cultural Transmission Hypothesis” and the “Alerting Others Hypothesis” of enemy recognition in birds was examined in mobbing experiments with captive blackbirds. Observer birds learned to mob a novel non-raptorial bird more strongly as a consequence of witnessing another bird mob strongly at the site of presentation. Strength of the observer's...

A distinction is made between fitness-enhancing aspects of a trait and selective force(s) that result in its optimization. Any functional explanation conceived to account for the occurrence of mobbing behaviour must explain both the benefits for the initiator and for the birds joining it. Nine teleonomic hypotheses are proposed that permit predicti...

The question of how territorial calls of the European pygmy owl come to elicit approach and/or mobbing responses from songbirds was investigated in areas both in and out of the owl's distribution. Great tits learned to respond to an artificial 800 Hz pure tone stimulus in both areas when the sound was presented in conjunction with both a multi-spec...

Some aspects of the general importance that studies of prediation have for a quantitative approach to problems of evolution are outlined. A specific study permits one to assess the principles of prey selection in a stickleback predator molding adaptive swarm formation in prey. Another study demonstrates an innate rejection of diverse edible prey in...

Problems related to feeding behavior in horses fall into three main categories: underconsumption, overconsumption, and abnormal consumption. Anorexia may be caused by a variety of diseases and overcome by removing the underlying causes (pain, fever), and physical or chemical stimulation of appetite. "Hypophagia" may be caused by poor dentition, dis...