Higher Perches Research Articles

Search Strategies of Wheatears (Oenanthe oenanthe) and Stonechats (Saxicola torquata): Adaptive Variation in Perch Height, Search Time, Sally Distance and Inter-Perch Move Length

SUMMARY (1) The foraging behaviour of six pairs of wheatears Oenanthe oenanthe and three pairs of stonechats Saxicola torquata was studied in a dry thornscrub area of N. Spain during the breeding season. (2) Wheatears were more diverse in their foraging mode using two main techniques, perch-to-ground sallying and running ground-gleaning. Stonechats were sallying specialists. Wheatears on average used lower perches than stonechats. (3) The distributions of successful and unsuccessful search times for both species resemble log-normal distributions. Departures from both types of perches occurred independently of the time already spent on the perch. Stonechats, on average, stayed longer on perches, and had lower departure rates from them than wheatears. (4) There appears to be no direct relationship between capture probabilities and departures from perches. Capture probabilities were lower for stonechats. Giving-up times and successful search times increased with perch height, and were longer for stonechats at the same perch heights. (5) This suggests that these birds were able to estimate how long it would take to search the area viewed from each perch, and that the height of the perch and probably the complexity of the area determine these giving-up times. There appears to be a difference in the detection ability or in the selection of prey between species. (6) Distant prey were more easily detected from high perches, as shown by the positive correlation between perch height and sally distance. Birds appeared to search systematically covering nearby areas first and progressively looking further away, as shown by the positive correlation between sally distances and successful search times. Stonechats sallied the same distances from higher perches and, on average, later than wheatears. (7) The return-to-perch rate of stonechats was twice that of wheatears. There was a marked resource depletion after the first use of a perch for wheatears, but not for stonechats. The return rate was negatively correlated with search times preceding the previous sally for wheatears, but not for stonechats. Again, the difference between species could be due to different detection efficiencies. (8) The distributions of move lengths between perches were also skewed to the right. Move length was positively correlated with perch height for both species. On average wheatears moved longer between perches than stonechats. These trends indicate that the size of the detection area from a perch determines the subsequent distance moved after giving up.

Use of Perches as Vantage Points During Foraging By Male and Female Stonechats Saxicola Torquata

AbstractThe behaviour of individual stonechats (Saxicola torquata) foraging in heathland habitats was studied, to reveal possible influences of the height of the perches used as vantage points on feeding efficiency. Feeding rates, methods of prey capture, time spent on perches, and perching heights were quantified for male and female birds in a pre-breeding, and breeding periods; in addition, the integration of foraging with pre-breeding male song behaviour was examined. Rates of prey capture were highly variable, showing no clear seasonal trends or sex differences. Perching heights averaged 1.0 m in spring, and 1.6 m in summer, and although sex differences were small, males tended to perch higher, and closer to the top of the vegetation, in spring. Comparison with randomly encountered perches showed that birds selected higher perches than the average available. Of three principal prey-capture techniques, only diving to the ground was used in spring, but flycatching, and snatching prey off foliage, were also employed in summer. The change correlated with the appearance of new prey types on the foliage of birch and bracken. Visits to perches were short, averaging 25 s, and showed no clear sex or seasonal differences, but tended to be longer on higher perches, up to 2 min. These data were combined to assess the profitabilty for foraging of different perching heights. For feeding by diving to the ground, the lowest heights provided the greatest capture rates, but for flycatching and snatching, very high perches were more successful. The birds' observed preferences for perches in spring corresponded to those allowing the highest chance of capture per visit, rather than per unit time. In summer, there was no correspondence. Birds departed from perches when their prospects of capture were still high, and thus the lengths of unsuccessful visits cannot be regarded as 'giving-up' times. In spring, the frequencies of foraging attempts and song-phrases were inversely related in short observation periods, and incompatibility of the activities was suggested by the different heights chosen (averaging 0.9 m for foraging, 1.8 m for singing). The lack of differences in the spring foraging behaviour of males and females (who do not sing) suggests that males separated their foraging and singing into discrete bouts. This was apparently accomplished by tactical allocation of time in stable conditions, rather than relegation of singing to times when foraging conditions were poor.

Seasonal Patterns of Song Production by Male Stonechats Saxicola torquata

Adult male Stonechats Saxicola torquata sang frequently while occupying exclusive breeding territories. Singing in the population started one month before nesting, when territorial disputes were most frequent, but individuals varied in their timing. Most males had a long period of singing at the start, and short periods of resurgence later in the season. The latter were timed just before re-nesting by the singer's mate, or by a neighbouring female. Within a nesting cycle, song-rates were highest before egg-laying, and declined to zero at hatching. Song was delivered from relatively high perches, and a disproportionate number were in parts of territories closest to neighbouring pairs. These results are consistent with the use of song to retain an

Effects of sex, strain and type of perch on perching behaviour in the domestic fowl

This paper reports a study of perching behaviour in the domestic fowl, in which the use of various types of perches by both sexes of three strains of pen-housed, 15-week-old chickens (‘S’ line, White Leghorn type; ‘T’ line, derived from a Rhode Island Red × Light Sussex cross; ‘J’ line, Brown Leghorn) was compared. The perching variables tested were the height and shape of the perch and the type of material (wood or wire) from which it was constructed. A preliminary experiment indicated that there was no avoidance of those areas of the pens in which the perches were subsequently placed. Both sexes used the perches equally, but strain was an important factor affecting perching behaviour. Birds of the ‘J’ line almost completely failed to use high perches, but usage was greater in ‘T’-line and greatest in ‘S’-line birds. These strain differences were not due to weight disparity or to social pressure. Individual preferences were observed. Some birds perched (perchers) where-as others did not (non-perchers). Repeated exposure increased the time spent on the perch by perchers but did not convert non-perchers into perchers. The type of material (wood or wire) from which the perches were constructed had little effect on behaviour. Low perches were used more than high ones, although they were never attractive, and square perches were used considerably more than lengths of wood. There were no significant preferences for wire or litter in ‘S’-line and ‘T’-line birds but ‘J’-line birds avoided wire. The welfare implications of these results are interesting. Low levels of perching on the length of wood, which is the type of perch most commonly used in semi-intensive housing, suggest that more appropriate perches could be designed. Although wire floors are commonly considered undesirable, ‘S’- and ‘T’-line birds showed no avoidance of wire. The results suggest that perching has a high genetic variance and, therefore, to keep, in line with industrial trends, it should be possible to select for birds which do and which do not perch.

Cooperative behavior and social organization of the Swallow-tailed Manakin (Chiroxiphia caudata)

The mating system of the Swallow-tailed Manakin (Chiroxiphia caudata) is a type of non-resource based polygyny in which males aggregate at traditional sites or leks to perform cooperative displays. Each lek and all its contained courts are used communally by a group of 4–6 males. Within the group a linear dominance hierarchy exists. Position in the hierarchy persists within and between years and at all courts and is inherited in linear sequence. The dominant male of the group behaves as a sentinel calling repeatedly from a high perch in an attempt to attract females to a court. When a female arrives, two or three males engage in a cooperative precopulatory dance, the Jump Display. This is followed by a Solo Precopulatory Display performed by a single male who, if successful, will copulate with the female. With rare exception, the dominant male performs all Solo Displays and all copulations. Display sequences that include both a Jump Display and Solo Precopulatory Display are more likely to lead to copulation than those consisting of only one part. Thus, the subordinates who help the dominant perform the dance are expending energy that increases his fitness without receiving any immediate benefit themselves. Several factors that may have contributed to the evolution of the mating system and cooperative displays of this species are considered.

Microhabitat selection for singing and other behaviour in great tits, Parus major: Some visual and acoustical considerations

Territorial male great tits ( Parus major L.) usually forage on the ground, sing from perches with a mean height of 9.3 m, and perform most other activities between 2 and 4 m. Analyses of their habitat's visual and acoustical stratification indicate that great tits sing from high perches to make themselves hard to locate visually rather than to make their songs carry farther. The birds' selection of inconspicuous singing spots is further substantiated by their striking preference for hawthorn trees, which have an extremely dense crown and produce leaves very early in the year.

The Dwarf Cuckoo in Venezuela

The Dwarf Cuckoo (Coccyzus pumilus) is a poorly known species; the only detailed observations of its breeding biology were made near Cali, Colombia by Ralph (Condor 77:60-72, 1975). Meyer de Schauensee (The species of birds of South America with their distribution, Livingston Publishing Co., Narberth, Pa., 1966) reported it as found in parts of Colombia and Venezuela in tropical and occasionally subtropical zones. Phelps and Phelps (Lista de las aves de Venezuela con su distribucion, Tomo 2, Parte 1, Bol. Soc. Venez. Ciencias Nat., 19, No. 90, 1958) described it as very locally distributed in Venezuela. I made the following observations on Fundo Pecuario Masaguaral, a cattle ranch in the state of Gu~irico, central Venezuela. This ranch is in the Venezuelan Ilanos, an extensive low-altitude grassland with scattered trees and occasional gallery forests. The habitat is designated as dry tropical woods by Ewel and Madriz (Zonas de vida de Venezuela, Ministerio de Agricultura y Cria, Republica de Venezuela, 1968). The llanos have a highly seasonal hydrology; rains from May through October flood the ground in places to a depth of over 50 cm; the other six months of the year are extremely dry. On the morning of 19 July 1973, I observed a Dwarf Cuckoo perched in some dense thorny bushes surrounding the base of an isolated palm tree in an area where the seasonal water was more than 30 cm deep. While preening, the cuckoo occasionally uttered a five to six note rattling churr. This call resembles a portion of the vocal duet of the White-bearded Flycatcher (Myiozetetes inornata), a permanent resident of the area. Another cuckoo answered briefly from the far side of the bushes. Ralph interpreted this call as a pair contact. The preening bird made another sound at about 11-sec intervals, a low single click which was accompanied each time by a shake of its body. Probably this is the same vocalization characterized by Ralph as cluck or tok. Later I found a nest in the same bushes, but on the side facing an open marsh. It was placed in a horizontal crotch of thorny branches at a height of 2 m. The nest was about 18 cm in diameter and constructed of small sticks so loosely put together that sky could be seen through it. A young cuckoo crouched on the supporting branch beside the nest. The juvenile cuckoo had a pale gray head and nape, and light brown back, wings and tail. Below, it was dirty white, entirely lacking the orange rufous throat and upper breast of the adult. The eye ring, which is red in the adult, was dull yellow. When the young bird heard the low clicks of an adult it became excited, gaped, then flew or glided down into the foliage. An adult cuckoo guarded the nest area, sometimes with vigor. A Smooth-billed Ani (Crotophaga ani) flew into the bushes and was immediately attacked and driven away. At another time a Gray-capped Cuckoo (Coccyzus lansbergi) landed in the bushes, but it left in haste after only a few seconds. On the other hand, a pair of preening Scaled Doves (Scardafella squammata) was tolerated in the nest bush and a pair of Pied Water-Tyrants (Fluvicola pica) nesting 4 m away was unmolested. About half an hour after I found the juvenile, an adult cuckoo, which proved to be male, flew into the bush with a large moth in his bill. The moth was buff-colored with a thick furry body about 3 cm long. The cuckoo called and was answered, then a second adult cuckoo met it on a small horizontal branch. The pair perched side by side and engaged in an active tug-of-war, each alternately pulling the moth. The male jerked the moth free and then both birds flew to a higher perch. While the moth struggled, the male cuckoo mounted the female, who grasped the insect's body as they copulated. When they separated, the male was still holding the moth, but the female pulled it away from him and tried to eat it. The moth freed itself and dropped down into thick foliage where the female cuckoo followed

Mesencephalic central gray lesions and fear-motivated behavior in rats

In Experiment 1, the performance of 11 rats with central gray lesions including complete destruction of the ventrolateral edge, 11 rats with comparable lesions but with only partial ventrolateral damage and 14 sham-operated controls was compared in an operant, shock-food conflict task. The animals with complete ventrolateral destruction accepted more shocks and accepted shocks at a higher intensity than controls, while the group with partial destruction showed intermediate results. In another test, the spontaneous activity of control animals was totally suppressed for 2 min following noxious shock but was unaltered in animals with complete ventrolateral destruction. In animals with partial lesions, post-shock activity was directly related to the amount of ventrolateral destruction. Both lesion groups explored significantly more than controls in an open field. In Experiment 2, employing different animals, 9 lesioned rats with complete or near-complete ventrolateral central gray destruction and 6 sham-operated controls were tested in a step-through passive avoidance task. The performance of the lesioned animals was greatly impaired. The open field and post-shock activity results of the first experiment were replicated in Experiment 2. When placed in the open field or on a high perch most controls but no lesioned animals defecated. Lesioned animals were significantly more active than controls during a 17-h observation period on an activity platform. It was concluded that the mesencephalic central gray matter, and in particular its ventrolateral aspect, is critical to the normal expression of fear in rats. Several alternative hypotheses were discussed.

Habitat utilization by cardinals in central and peripheral breeding populations

Color-banded male cardinals, Richmondena cardinalis, were observed in a dense population in Tennessee and in a sparse one in Ontario. Continuous observations were made, using a tape recorder, of a bird's behavior relative to the cover-forms comprising its habitat. Frequencies of cover-forms occurring in home ranges were obtained by sampling, and a measure of a cardinal's discrimination among them was obtained using an extension of Shannon's formula. Peripheral birds showed higher discrimination in foraging sites than central birds. Cardinals in both regions showed strong discrimination among habitat features for singing and foraging. In the peripheral region, cardinals showed strong preference for non-coniferous song perches, and either actively avoided coniferous foliage or preferred other types for foraging. All nests were in coniferous foliage. Discrimination between foliage types was not so marked in the central region, where conifers occurred less frequently. Throughout its range, the cardinal requires suitable woody cover for nesting. There is evidence that males prefer high song perches, but height seems less important than conspicuousness.

The Worst Is Over

THE last twenty years have been like a nightmare to us language teachers, but let us forget the past and look forward to a more encouraging future. There is no point in indulging in useless recriminations about the Modern Foreign Language Study and its impossible challenge of giving our students any reasonable command, oral and written, of any language in two years. Nor would gain anything by whining about the way school administrators shunted out the courses in mathematics and foreign languages on the ground that they were too difficult. We can now smile at these same educationalists who shooed our American youth into vocational and technical programs during the great depression to prepare the young people for industry and commerce when there were no jobs to be had. You can now read with some degree of equanimity and without fear educational pamphlets like the famous What the High Schools Ought to Teach which was a most ridiculous indictment of our subject. No longer should be indignant at the story that when our foreign language teachers offered the languages for the war effort, administrators laughed at our spokesmen on the pretext that there was no place for the foreign languages in the war effort. In fact, one of the most important superintendents of one of the largest cities in the United States shouted and dismissed us with a Falstaffian laugh, we don't need foreign languages, need soldiers. Let first things come first. Today languages are a recognized part of the war effort, and while much time was lost before the Government finally realized their importance, they are today an essential part of training programs in camps, in A.S.T.P. courses, and in many Government training divisions. Yet, must not fall asleep and expect that our nightmare will suddenly change into a rosy, dreamy paradise. We must prepare for the peace effort. We must lift ourselves by our own bootstraps. No doubt the same confusion, squabbles and opposition in the new period of the global peace will arise. Nor will superintendents and principals come down from their high perch to beg us to teach languages again. We shall be told that the world needs producers and not linguists. Yet, how will dispose of our goods and services to the world if cannot communicate with people of other languages? Will technicians with no knowledge of foreign languages be able to communicate with foreigners? No, shall have to carry our message to the public, the parents and even the pupils themselves. These must demand the inclusion of the languages in the new educational curricula after the war. That foreign languages have been taught successfully in the Government programs will only affect us indirectly. We cannot hope to devote

Life History of the California Condor Part III. Home Life of the Condors

N the issue of THE CONDOR for November, 1906, I gave an account of finding the nest and egg of a California Condor ( Gymnogyps californianus) in the mountains of southern California, which was accomplished thru the help of Mr. Joseph Grinnell and Mr. Walter P. Taylor. In the last issue, January, 1908, I dealt with the historical data and range of the California Condor. Most of the material used was supplied me thru the kindness of Mr. W. Lee Chambers, who has spent years in collecting this data. In the present paper I shall continue the observations Mr. Bohlman and I made at the condor's nest, and tell something of the home life of these birds. From what we knew of the nesting habits of the California Condor, we could not tell whether the old birds would be shy and hard to photograph, or whether they would show fight while we were working at their home. On April 11, 1906, we made another trip to the condor's cave. While ascending the steep slope to the nest, a large bowlder was accidentally loosened and narrowly missed taking the camera man along as it dropped into the canyon with a loud report. The next moment, the old condor, aroused from her nest, flapped to her perch in the dead tree directly over our heads. We watched and waited, hoping she would return to the nest. But after about fifteen minutes, she raised her wings, hooked her bill about the stump, parrot fashion, and climbed to a higher perch. We crawled on up behind a cover of rocks to get a picture. While fixing the camera, I looked up and the old male was just alighting beside his mate on the dead tree. We crouched down to watch. If the birds saw us, they paid no attention to our presence. The mother edged along the limb and put her head under his neck. Then she nosed him as if asking to be fed, but he responded rather coldly by moving away and she followed. This crowded him out where the limb was