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Oak savanna, once widespread across central North America, has functionally vanished from most of its range due to land conversion or fire suppression and subsequent afforestation. Savanna-associated bird species have exhibited population declines as a result. One of the few areas containing remnant oak savanna is the vast Cross Timbers ecoregion of the south-central Unites States. Previous research in the Midwest showed some bird species exhibited higher rates of nest success (i.e., lower predation of eggs and nestlings) in restored savannas than in closed-canopy forests. Our objective was to quantify patterns of avian nest success across a gradient from open-canopy oak savanna to closed-canopy forest in the Cross Timbers ecoregion of southeastern Kansas. Daily nest survival rates for four common bird species--mourning dove (Zenaida macroura), yellow-billed cuckoo (Coccyzus americanus), brown thrasher (Toxostoma rufum), and northern mockingbird (Mimus polyglottos)-- were modeled against covariates of woodland structure along the habitat gradient. Tree density and canopy cover had no significant effects on daily nest survival rate, but daily survival rates of brown thrasher and northern mockingbird nests showed positive trends with increasing shrub density. We expect restoration of oak savanna habitat would have little effect on nest survival of some common bird species in the naturally heterogeneous Cross Timbers ecoregion., INTRODUCTION Oak-prairie savanna habitat in the Midwestern United States has largely disappeared (Nuzzo, 1986: Henderson, 1995; Noss et al., 1995). Land conversion and degradation due to fire suppression have been [...]

We review the taxonomic history, external morphology, anatomy, behavior, distribution, and zoogeography of the Blue-headed Quail-Dove (Starnoenas cyanocephala), which is endemic to Cuba, and conclude that it is completely unlike any other New World member of the Columbidae. It presents a mosaic of characters shared with various genera in Australasia but is perhaps most similar to the Australian genus Geophaps and related terrestrial pigeons. The Blueheaded Quail-Dove should be placed in its own subfamily, Starnoenadinae, until its relationships with Australasian genera can be refined by additional data including molecular. We recommend that the English name be changed to Blue-headed Partridge-Dove. Received 9 October 2015. Accepted 17 November 2015. Key words: anatomy, behavior, Columbidae, Geophaps, Geotrygon, paleontology, Starnoenadinae, zoogeography., Received wisdom often distorts our perception of relationships among various groups of birds until new information or more critical evaluation of old evidence dispels the inaccuracy of current knowledge. A [...]

In Experiment 1, 2 groups of pigeons were trained to respond to either a 4-item (A[right arrow]B[right arrow]C[right arrow]D) or 5-item (A[right arrow]B[right arrow]C[right arrow]D[right arrow]E) list. After learning their respective list, half of the subjects were trained on a positive pair with reinforcement provided when pairs were responded to in the order true to that of the original sequence (4-item: B[right arrow]C; 5-item: B[right arrow]D). The remaining subjects were trained on a negative pair with reinforcement provided for responding to the pairs in the order opposite to that learned in the original sequence (4-item: C[right arrow]B; 5-item: D[right arrow]B). Subjects in the positive pair condition learned their respective pair faster than did subjects in the negative pair condition. In Experiment 2, after reaching criterion on a 4-item list, subjects received 16 BC probe trials spread across 4 sessions of training. Subjects performed significantly above chance on the probe trials. The performance of our subjects in Experiments 1 and 2 demonstrates that, similar to monkeys, pigeons form a representation of the lists that they learn. Keywords: serial order, representation, chaining theory DOI: 10.1037/a0020926

A basic tenet of principles of associative learning applicable to models of spatial learning is that a cue should be assigned greater weight if it is a better predictor of the goal location. Pigeons were trained to locate a goal in an acute corner of an isosceles trapezoid arena, presented on a slanted floor with 3 (Experiment 1) or 2 (Experiment 2) orientations. The goal could be consistently determined by the geometric shape of the arena; however, its position with respect to the slope gradient varied, such that slope position was not a good predictor of the goal. Pigeons learned to solve the task, and testing on a fiat surface revealed successful encoding of the goal relative to the geometric shape of the arena. However, when tested in the arena placed in a novel orientation on the slope, pigeons surprisingly made systematic errors to the other acute--but geometrically incorrect--mirror image corner. The results indicate that, for each arena orientation, pigeons encoded the goal location with respect to the slope. Then, in the novel orientation, they chose the corner that matched the goal's position on the slope plus local cue (corner angle). Although geometry was 2 times (Experiment 2) or even 3 times (Experiment 1) as predictive as slope, it failed to control behavior during novel test trials. Instead, searching was driven by the less predictive slope cues. The reliance on slope and the unresponsiveness to geometry are explained by the greater salience of slope despite its lower predictive value. Keywords: goal location, slope or geographical slant, geometric shape, cue salience, Columba livia DOI: 10.1037/a0019234

Animals that travel together in groups display a variety of fascinating motion patterns thought to be the result of delicate local interactions among group members (1-3). Although the most informative way of investigating and interpreting collective movement phenomena would be afforded by the collection of high-resolution spatiotemporal data from moving individuals, such data are scarce (4-7) and are virtually non-existent for long-distance group motion within a natural setting because of the associated technological difficulties (8). Here we present results of experiments in which track logs of homing pigeons flying in flocks of up to 10 individuals have been obtained by high-resolution lightweight GPS devices and analysed using a variety of correlation functions inspired by approaches common in statistical physics. We find a well-defined hierarchy among flock members from data concerning leading roles in pairwise interactions, defined on the basis of characteristic delay times between birds' directional choices. The average spatial position of a pigeon within the flock strongly correlates with its place in the hierarchy, and birds respond more quickly to conspecifics perceived primarily through the left eye--both results revealing differential roles for birds that assume different positions with respect to flock-mates. From an evolutionary perspective, our results suggest that hierarchical organization of group flight may be more efficient than an egalitarian one, at least for those flock sizes that permit regular pairwise interactions among group members, during which leader-follower relationships are consistently manifested., Collective movement phenomena in animals include many spectacular and familiar examples: among birds, seemingly instantaneous changes in a flock's direction of motion, the abrupt splitting of a flock, or a [...]

Long-distance dispersal (LDD) of plants remains as a little-understood, key ecological process. We present evidence indicating that granivorous pigeons may disperse large amounts of viable seeds when they die with seeds in their crops at long distance from the parent plant. Research was conducted in Eared Dove (Zenaida auriculata) breeding colonies in central Argentina where breeding populations may reach over 8000 doves/ha. We measured (a) crop seed viability and germination rate from dead doves and (b) daily travel distance from the breeding colonies to the feeding grounds. Seed viability was over 50% in fresh adult and nestling samples. Seed-germination rate ranged between 35% and 65%, even in corpses left on the ground for 30 days. Maximum doves' daily flight distance from the breeding colonies was 117 km. The estimated annual seed deposition per hectare resulting from crop spillage in two breeding colonies was 10.95 and 9.66 Mg, respectively. Significant ecological implications of dove-crop spillage include seed dispersal among fragments, rapid colonization of new habitats including islands, and dispersal of large volumes of weed and transgenic material. A preliminary assessment of dispersal kernel generated by crop spillage in colonial Eared Doves is included. Key words: Cordoba province, Argentina; Croton; dove weeds; Eared Dove breeding colonies; long-distance dispersal; pigeons; transgenic material dispersal; weed dispersal; Zenaida auriculata.

Three pigeons were trained in a successive same/different (S/D) procedure using compound auditory stimuli (pitch/timbre combinations). Using a go/no-go procedure, pigeons successfully learned to discriminate between sequences of either all same (AAAA ... or BBBB ...) or all different (ABCD ...) sequences consisting of 12 sounds. Both pitch and timbre were subsequently established as controlling dimensions. Transfer tests with novel stimuli revealed a generalized basis for the discrimination (novel pitch/timbre combinations, novel pitches, novel instruments, and complex natural & man-made sounds). These results indicate for the first time that pigeons can learn generalized same/different discriminations in a nondominant modality. When combined with earlier visual results, they support a qualitative similarity among birds and primates in their capacity to judge this type of fundamental stimulus relation across different modalities. Keywords: audition, relational discrimination, same-different discrimination, pigeon, birds

Three experiments assessed the relation between the differential outcomes effect and resistance to change of delayed matching-to-sample performance. Pigeons produced delayed matching-to-sample trials by responding on variable interval schedules in two components of a multiple schedule. In the same-outcome component, the probability of reinforcement was the same for both samples (.9 in Experiments 1 and 2, .5 in Experiment 3); in the different-outcomes component, the probability of reinforcement was .9 for one sample and .1 for the other. In all three experiments, the forgetting functions in the different-outcomes component were higher and shallower than in the same-outcomes component. When total reinforcement was greater in the same-outcomes component (Experiments 1 and 2), resistance to disruption by prefeeding, intercomponent food, extinction, or flashing lights typically was greater in that component. In Experiment 3, when total reinforcement was equated, resistance to disruption was similar across components. Thus, the level and slope of forgetting functions depended on differential reinforcement correlated with the samples, but the resistance to change of forgetting functions depended on total reinforcement in a component. Both aspects of the results can be explained by a model of delayed matching to sample performance. Keywords: delayed matching to sample, differential outcome effect, probability of reinforcement, resistance to change, pigeons

Byline: R. Tabassum, S. Hussain, H. Kali and S. Abbas ABSTRACT An experiment was carried out to estimate the effect of different energy levels of diets on weight of body [...]

Microbiological characterization of the bacteriocyte-associated symbiotic bacterium in slender pigeon louse, Columbicola columbae is presented using molecular phylogenetic analyses and histological techniques.

Sexual size dimorphism is a conspicuous trait of many wild bird species. Differences in body size between the sexes might reflect selective pressures and trade-offs to optimize performance. Here, we analyze the size dimorphism of the Galapagos Dove (Zenaida galapagoensis) using principal component and discriminant analyses with samples obtained from six islands: Santiago, Santa Fe, Santa Cruz, Espanola, Genovesa, and Wolf. We also reanalyze published morphological data but also including additional samples from Wolf Island to account for morphological differences among islands. Males were significantly larger than females. Discriminant analyses correctly classified 98% of males and 100% of females, and cross-validation of the model correctly classified 97% of males and 98% of females. We created two sexual size dimorphism indices using wing chord and tarsus as body-size surrogates. Significant differences were found in the sexual size dimorphism index for both measurements among islands. Significant differences in sexual size dimorphism among islands might indicate the role of different selective pressures acting on individual islands (e.g., competition, predation, resources, sexual selection), which might result in life history variation of the species among islands. For the first time, we provide significant morphological evidence supporting the classification of the Galipagos Dove into two subspecies: Z. g. galapagoensis and Z. g. exsul. Key words: Galapagos, morphology, sexual size dimorphism. Zenaida galapagoensis. El dimorfismo sexual de tamano es una caracteristica comun de muchas especies de aves. Las diferencias en el tamano corporal entre machos y hembras puede reflejar la accion de factores de seleccion y soluciones de costo-beneficio que actuan para optimizar el rendimiento de las aves en su ambiente. Analizamos el dimorfismo de tamano de Zenaida galapagoensis por medio de anilisis de componentes principales y anilisis de discriminacion utilizando muestras colectadas en seis islas: Santiago, Santa Fe, Santa Cruz, Espanola, Genovesa y Wolf. Tambien reanalizamos informacion morfologica previamente publicada, en donde incluimos muestras provenientes de la isla Wolf la cual no estuvo comprendida en el esudio anterior, para analizar diferencias morfologicas entre las islas. Los machos fueron significativamente mas grandes que las hembras. El analisis de discriminacion clasifico correctamente el 98% de los machos y el 100% de las hembras, el analisis de validacion del modelo de discriminacion clasifico correctamente el 97% de los machos y el 98% de las hembras. Creamos un indice de dimorfismo sexual de tamano utilizando la cuerda alar y el tarso como medidas de tamano corporal. Se encontraron diferencias significativas en el dimorfismo sexual de tamano entre algunos pares de islas para ambas medidas. Diferencias significativas en el dimorfismo sexual de tamano pueden indicar la accion de diferentes presiones selectivas en diferentes islas (e.g., competicion, depredacion, recursos, seleccion sexual), lo cual puede crear variaciones en la biologia de la especie entre las distintas islas. Por primera vez, proveemos resultados morfologicos significativos que apoyan la separacion de Z. galapagoensis en dos subespecies: Z. g. galapagoensis y Z. g. exsul.

The present experiments examined whether pigeons can sum symbols that are associated with various temporal consequences in a touch screen apparatus. Pigeons were trained to discriminate between two visual symbols that were associated with 0, 1, 2, 3, 4, or 5 s either of delay to 4 s of hopper access (delay group) or duration of hopper access (reward group). In Experiment 1, the pigeons in both groups learned to select the symbol associated with the more favorable outcome, and they successfully transferred this discrimination to novel symbol pairs. However, when tested with 2 pairs of symbols associated with different summed durations, they responded on the basis of a simple response rule rather than the sum of the symbol pair. In Experiment 2, the reward group was presented with four symbols at once and was allowed to successively choose one symbol at a time. All pigeons chose the symbols in order from largest to smallest. This indicates that pigeons formed an ordered representation of symbols associated with different time intervals, even though they did not sum the symbols. Keywords: pigeons, symbol use, temporal representation, summation, ordinality

Experiment 1 showed that the Hick--Hyman law (W. E. Hick, 1952; R. Hyman, 1953) described the effects of anticipated reinforcement, a form of incentive, on pigeons' (Columba livia) reaction time to respond to a target spatial location. Reaction time was an approximately linear function of amount of information interpreted as probability of reinforcement, implying that pigeons processed incentive at a constant rate. Experiment 2 showed that the Hick--Hyman law described effects of incentive even when it varied from moment to moment in a serial reaction time task similar to that of M. J. Nissen and P. Bullemer (1987), and processing information about target spatial location modulated absolute reaction time and not rate of processing incentive. The results support mental continuity and provide comparative support for the idea of the economics of information in economic theory about the incentive value of information. Keywords: incentive, anticipated reinforcement, Hick--Hyman law, reaction times, pigeons

Absolute pitch (AP) is the ability to classify individual pitches without an external referent. The authors compared results from pigeons (Columba livia, a nonsongbird species) with results (R. Weisman, M. Njegovan, C. Sturdy, L. Phillmore, J. Coyle, & D. Mewhort, 1998) from zebra finches (Taeniopygia guttata, a songbird species) and humans (Homo sapiens) in AP tests that required classification of contiguous tones into 3 or 8 frequency ranges on the basis of correlations between the tones in each frequency range and reward. Pigeons' 3-range discriminations were similar in accuracy to those of zebra finches and humans. In the more challenging 8-range task, pigeons, like zebra finches, discriminated shifts from reward to nonreward from range to range across all 8 ranges, whereas humans discriminated only the 1st and last ranges. Taken together with previous research, the present experiments suggest that birds may have more accurate AP than mammals. Keywords: absolute pitch, comparisons with humans and songbirds, frequency-range discriminations, pigeons, zebra finches

Adult humans (Homo sapiens) and pigeons (Columba livia) were trained to discriminate artificial categories that the authors created by mimicking 2 properties of natural categories. One was a family resemblance relationship: The highly variable exemplars, including those that did not have features in common, were structured by a similarity network with the features correlating to one another in each category. The other was a polymorphous rule: No single feature was essential for distinguishing the categories, and all the features overlapped between the categories. Pigeons learned the categories with ease and then showed a prototype effect in accord with the degrees of family resemblance for novel stimuli. Some evidence was also observed for interactive effects of learning of individual exemplars and feature frequencies. Humans had difficulty in learning the categories. The participants who learned the categories generally responded to novel stimuli in an all-or-none fashion on the basis of their acquired classification decision rules. The processes that underlie the classification performances of the 2 species are discussed. Keywords: adult humans, categorization, decision rule, pigeons, prototype effect

Past evidence that pigeons may adopt a single-code/default strategy to solve duration sample discriminations may be attributable to the similarity between the intertrial interval (ITI) and the retention interval. The present experiments tested whether pigeons would adopt a single-code/default strategy when possible ITI-retention-interval ambiguity was eliminated and sample salience was increased. Previous studies of duration sample discriminations that have purported to show evidence for the use of a single-code/default coding strategy have used durations of 0, 2, and 10 sec (Zentall, Klein, & Singer, 2004). However, the results of Experiment 1 suggest that the use of a 0-sec sample may produce an artifact resulting in inadvertent present/absent sample matching. In Experiment 2, when pigeons were trained with three nonzero duration samples (2, 8, and 32 sec), clear evidence for the use of a single-code/default strategy was found.

We investigated whether pigeons are able to discriminate color photographs of male and female pigeons, using a categorical discrimination procedure. In Experiments 1 and 2B, 10 out of 14 pigeons learned the discrimination. Of these, 5 pigeons showed transfer to novel stimuli, demonstrating the categorical nature of the trained discrimination. Experiment 3 showed that the discriminative behavior was based primarily on the body, as opposed to the head and the neck region. In 1 out of 3 pigeons, the discriminative behavior was maintained by the black-and-white photographs. The results suggest that some pigeons have the ability to discriminate the sex of conspecifics without behavioral cues.

The authors examined how pigeons (Columbia livia) perform on 2-dimensional maze tasks on the LCD monitor and whether the pigeons preplan the solution before starting to solve the maze. After training 4 pigeons to move a red square (the target) to a blue square (the goal) by pecking, the authors exposed them to a variety of detour tasks having lines as a harrier. A preview phase was introduced, during which the pigeons were not allowed to peck at the monitor. Results of a set of experiments suggest that our pigeons successfully learned to solve these tasks, that they came to take an efficient strategy as the barriers became complex, and that they possibly preplan its solution, at least on familiar, well-practiced tasks. Keywords: pigeons, maze, navigation, preplanning Supplemental materials: http://dx.doi.org/10.1037/0735-7036.120.4.358.supp

A study on blind imitation behavior of pigeons based on food reward experiment is presented

Four pigeons were given repeated reversal training and testing with photographs of human faces constituting two categories structured by family resemblances, each consisting of a prototype, good exemplars, and poor exemplars. Each of the good exemplars (AM, BM, and CM) was created by 50% morphing of the prototype (M) and one of the poor exemplars (A, B, and C, respectively) and thus was physically similar to the prototype and to the corresponding poor exemplar. The pigeons were first trained and tested for the formation of two (AM, BM, and CM) classes. Then, the stimulus sets were extended to include (1) M and the poor exemplars that were not physically similar to one another and (2) 50% morphs of the poor exemplars (AB, BC, and CA). In the sequentially introduced training and test phases, we successfully tracked expansion of the functional equivalence classes consisting of exemplars that had little similarity but could be linked together through other members of the class.

Pigeons trained in a conditional discrimination procedure to respond to a visual array made a left or right choice, depending on which of two numbers of elements (i.e., anchor numerosities) the array contained. They were then tested with novel arrays at these anchor numerosities, as well as at interpolated and extrapolated numerosities. Various control conditions showed that the birds' discrimination performance was primarily based on stimulus numerosity, and not on other factors, such as brightness or area. Results from a series of tests, spanning a wide range of numerosities, conformed to scalar principles. Psychometric functions showed superposition, indicating that Weber's law applies to numerosity discrimination. The subjective midpoint between anchor values was at the geometric mean. Variability about this bisection point increased in proportion to the numerical value of the mean.

Success in tasks requiring categorization of pictorial stimuli does not prove that a subject understands what the pictures stand for. The ability to achieve representational insight is by no means a trivial one because it exceeds mere detection of 2-D features present in both the pictorial images and their referents. So far, evidence for such an ability in nonhuman species is weak and inconclusive. Here, the authors report evidence of representational insight in pigeons. After being trained on pictures of incomplete human figures, the birds responded significantly more to pictures of the previously missing parts than to nonrepresentative stimuli, which demonstrates that they actually recognized the pictures' representational content. Keywords: picture-object recognition, categorization, representation, pigeon

Abstract This article deals with the aesthetics of the sounds of ring-necked doves and African ground hornbills among the Wawanji people of the Iringa region in the southern highlands of [...]

A go/no-go procedure was used to train pigeons to discriminate pictures of human faces differing only in shape, with either static images or movies of human faces dynamically rotating in depth. On the basis of experimental findings in humans and some earlier studies on three-dimensional object perception in pigeons, we expected dynamic stimulus presentation to support the pigeon's perception of the complex morphology of a human face. However, the performance of the subjects presented with movies was either worse than (AVI format movies) or did not differ from (uncompressed dynamic presentation) that of the subjects trained with a single or with multiple static images of the faces. Furthermore, generalization tests to other presentation conditions and to novel static views revealed no promoting effect of dynamic training. Except for the subjects trained on multiple static views, performance dropped to chance level with views outside the training range. These results are in contrast to some prior reports from the literature, since they suggest that pigeons, unlike humans, have difficulty using the additional structural information provided by the dynamic presentation and integrating the multiple views into a three-dimensional object.