Does Familiarity with the Release Site Influence the Initial Orientation of Homing Pigeons? Experiments with Clock-shifted Birds

Experiments were performed to test whether the familiarity with the release site plays a role in the initial orientation of homing pigeons. Repeated releases of 6 h clock-shifted birds from the same site during the shifting time produced an improvement of their initial orientation: the shift effect decreased progressively. Since in subsequent releases from unfamiliar sites the shift effect reappears, the course correction observed at the familiar site is attributable to local stimuli and not to a general recalibration of the sun compass.     

Pigeon navigation: Time course of olfactory signal processing and dependence on access to fresh environmental air

Summary 16 releases, centrally symmetrical by pairs and involving distances of displacement from 25 to 172 km, were conducted with homing pigeons pre-treated in different ways: FIL birds were, until few minutes before release, confined to containers ventilated with ambient air that had passed through filters consisting of activated charcoal. NOFIL birds were confined to containers ventilated with unfiltered air, either from departure at the loft onwards (4 experiments) or for at least 4 h at the release site (after transport under FIL conditions; 12 experiments). The olfactory epithelia of XYL birds were locally anaesthetized a few minutes before release, while NOXYL birds were not treated with xylocain. FIL/NOFIL conditions were combined with XYL/NOXYL conditions, resulting in 4 types of experimental treatment.On average, the untreated pigeons (NOFILNOXYL) were best homeward oriented and the double-treated pigeons (FIL-XYL) poorest. More importantly, the effect of olfactory deprivation during initial flight alone (NOFIL-XYL) was small, whereas long-term filtration of environmental air was quite effective even if the pigeons could smell during release time (FIL-NOXYL) (Fig. 5).These findings indicate that pigeons usually need to be exposed to local odorous air for more than only few minutes in order to utilize information extricated from this air for site localization.Additional experiments showed that homeward orientation is also prevented, if the pigeons, although breathing natural air, are ventilated with restricted volumes of fresh air.Our results are discussed with regard to the homing mechanism of pigeons as well as to their methodological consequences.Abbreviations FIL breathing air filtered by charcoal - NOFIL breathing air unfiltered - XYL xylocain applied to pigeons' nostrils - NOXYL no xylocain applied (see p. 140)     

Acetylcholine as sensory transmitter in crustacea

Summary In an attempt to learn more about the so-called map component in pigeon navigation, nine series of tests comprising 34 test releases were performed at a release site, 89 miles NNE of Ithaca, New York, where Cornell pigeons regularly depart nonrandomly but with a large clockwise deviation from the true home direction. The tests included releases of: (1) experienced pigeons new to the site, under sun; (2) pigeons with previous experience at the site, under sun; (3) experienced pigeons new to the site, under total overcast; (4) pigeons with previous experience at the site, under total overcast; (5) first-flight youngsters, under sun; (6) directionally trained pigeons; (7) pigeons from two other Ithaca-area lofts; (8) pigeons from two more distant lofts; (9) Bank Swallows from an Ithaca colony; (10) clock-shifted pigeons; (11) radio- and airplane-tracked pigeons.The results of these tests indicate that the directional bias of the Cornell pigeons is, in general, not dependent on weather conditions or on the previous experience of the birds. Moreover, a similar bias is shown by both pigeons from other Ithacaarea lofts and Bank Swallows from Ithaca. And a similar bias from their respective home directions is shown by birds from other areas. Clock-shifted pigeons departing more directly toward home have poorer homing success than controls. It is concluded that some environmental factor basic to the avian homing process is rotated clockwise at this release site, that biologically the birds are not making an error but are probably reading correctly a distorted map.I thank Irene Brown and Timothy Larkin for their aid in all phases of this project; Donald Windsor for help in two releases; Charles Walcott and Martin Michener for aid in airplane tracking; J. Downhower for collaboration in the radio tracking and swallow releases; Andre Gobert, Howard French, A. E. Newton, and Ludwig Karl for permitting me to use their pigeons, George Yerdon, Forest Ranger, and Andy Misura, District Ranger, New York State Department of Environmental Conservation, for their cooperation in making the facilities of the Castor Hill Fire Tower available to us; Monica Howland for preparing the drawings; and Bertha Blaker for typing. Research supported in part by NSF Grants GB-13046X and GB-35199X, and in part by Federal Hatch funds.     

Effects of flight on blood parameters in homing pigeons

The influence of flight and flight duration on 13 blood parameters was studied in homing pigeons which returned after 2–22 h of flight from release sites 113–620 km away. The haematocrit value decreased from 54.4% in controls to 51.0% in the flown birds. A lowered haematocrit overproportionately improves blood flow. The plasma concentrations of glucose and l(+)-lactate did not differ between experimental and control birds. This is compatible with the idea that carbohydrates are utilized as fuel mainly in the initial phase of flight. Plasma free fatty acid levels were significantly increased during flight and triglyceride concentrations gradually decreased with progressive flight duration. These findings support the view that lipids are the main energy source during flight. Plasma uric acid concentrations were increased two- to fourfold in flown birds. Urea levels gradually rose with flight duration to 400% of controls. Plasma protein concentration was lowered in flown pigeons. These results hint to an increased protein degradation during flight. Na⁺, K⁺, Ca²⁺, and Mg²⁺ levels in the plasma of the flown pigeons were not significantly different from control values. This finding together with the urea/uric acid ratio indicates that no severe dehydration occurred in our pigeons during free-range flight.Abbreviations FA fatty acids - FFA free fatty acids     

Pigeons in the sun: Thermal constraints of eumelanic plumage in the rock pigeon (Columba livia)

In wild vertebrates, several species exhibit eumelanic color polymorphism with the coexistence of dark and light morphs. The maintenance of such polymorphism suggests the existence of a selective balance between the morphs and a large body of literature has reported the costs and benefits of darker plumage coloration in birds. Among them, it has been suggested that melanin and dark plumage could entail high energetic costs especially under hot and sunny climates. However, to my knowledge, the thermal constraints of sun exposure have rarely been studied in polymorphic species. Here, we tested the impact of eumelanic plumage coloration on plumage and body temperatures, and evaporative cooling behavior in the polymorphic rock pigeon (Columbia livia). We experimentally exposed light and dark pigeons to direct sun radiation for 1 h while a few birds were maintained in the shade as controls. We found that sun exposure was associated with increased plumage temperature, and this effect was greater for darker pigeons. In addition, we found that sun exposure was also associated with higher cloacal temperature but for dark pigeons only. Finally, light and dark pigeons were more likely to show cooling evaporative behavior when exposed to sun and as their cloacal temperature increases. Altogether, these results suggest that darker pigeons may have a lower ability to cope with heat and solar radiations and that dark plumage can be associated with thermal costs in this polymorphic species.     

How does time since feeding affect the fuels pigeons use during flight?

Time between meals can vary from multiple hours to days within and among species. We investigated the effects of time since feeding on lipid, protein, and carbohydrate oxidation in flying pigeons (Columba livia) by interpreting changes in blood plasma metabolite concentrations and mass during flight. Five pigeons were flown or rested for 4 h after food deprivations of 2, 12, 24, and 48 h. After flight, blood plasma concentrations of uric acid and beta-hydroxybutyrate were elevated over control and preflight values, indicating elevated protein and lipid catabolism during flight. Lipid oxidation, as indicated by changes in beta-hydroxybutyrate concentration, increased more in unfed flying pigeons compared with recently fed flying pigeons and with resting controls. Protein oxidation, as indicated by changes in uric acid concentrations, also positively covaried with feeding time; the covariation was mostly caused by increases in 48-h food-deprived pigeons. Unfed birds lost less mass during a 4-h flight than recently fed birds. We reasoned that recently fed pigeons oxidized more glycogen in flight than pigeons not recently fed; calculated glycogen stores explained 72%-117% of mass loss differences between 2- and 48-h-fed pigeons. Thus, time since feeding was an important determinant of the fuels pigeons used in flight.     

Pigeon Homing: Does Early Experience Determine what Cues are Used to Navigate?

To test the hypothesis that early experience might determine the nature of the cues used to navigate, homing pigeons were made anosmic by nerve section before they could experience the natural odours in the region of the loft. They were allowed to make free flights and trained by flock releases with intact controls. Next they were tested and compared with intact controls as well as birds made temporarily anosmic just before the experiment. Initial orientation and homing performance of the experimental birds were very poor and showed that the pigeons were unable to acquire an alternative mechanism of navigation.     

Orientation by pigeons deprived of olfaction by nasal tubes

Summary In an effort to avoid the trauma and other nonolfactory effects produced by surgical sectioning of pigeons' olfactory nerves, and to avoid the interference with breathing produced by nostril plugs, a way of making pigeons anosmic by inserting plastic tubes in their nostrils was developed. A total of 16 experimental releases were conducted from unfamiliar sites to compare the homing behavior of birds wearing a tube in each nostril with controls wearing a tube in only one nostril. In five short-distance releases (less than 25 km), no convincing differences in initial orientation, vanishing intervals, or homing success were observed. In eleven releases from longer distances (more than 76 km), the experimental birds were random in three cases and the controls were random in two. In no case were the differences in the distributions of the bearings of experimental and control birds statistically significant, nor were there ever significant differences in vanishing intervals. However, experimental birds had much poorer homing success from these long-distance releases. It is concluded, in view of the anosmic pigeons' good orientation at distant unfamiliar sites, that olfaction is not necessary for homeward orientation and hence that it cannot be the basis of the birds' navigational map. Poor homing success from long distances is probably a consequence of the physical irritation and interference with breathing unfortunately produced by the nasal tubes.We thank our colleagues, Irene Brown, Timothy Larkin, and André Gobert for their help in conducting the releases. This research was supported by Grant BMS 75 18905 AO2 from the National Science Foundation.     

Changes in the short-term deflector loft effect are linked to the sun compass of homing pigeons

Despite being the most studied of all avian orientation systems, important questions still remain about the sun compass of homing pigeons, Columba livia. White it is well-documented that the sun compass is usually learned by young pigeons during the first 10–12 weeks of life, the mechanism by which it is calibrated to adjust for seasonal changes in the sun's azimuth is not known with certainty. Previous experiments using short-term deflector loft pigeons indicated that the sun compass may be calibrated by referencing celestial polarization patterns. The present paper describes important measurable changes in the previously reported orientation behaviour of short-term deflector loft birds, and suggests a correlation between these changes and the presence of a massive upper-atmospheric dust cloud of volcanic origin which significantly altered natural skylight polarization patterns in 1982 and 1983. Moreover, it is shown that when the short-term effect was absent (at times when data from previous years suggested it should be present), the birds were also not using sun compass orientation, as demonstrated by their failure to show the standard ‘clockshift’ response to a 6-h fast shift of their internal clocks. These results support the hypothesis that reflected light cues, rather than odours, are the basis of the deflector loft effect in pigeon homing.     

The effect of habitat and number of inhabitants on the population sizes of feral pigeons around towns in northern Poland

Most studies on factors influencing density of the feral pigeons Columba livia var. domestica were carried out in large cities and agglomerations. However, also in small towns, pigeons are important epidemiological and sanitary problem. In our studies, feral pigeons were censused in 33 towns located in the Pomeranian Province (northern Poland) during 2006–2008. These birds occurred in 19 (57.6%) towns. The number of pigeons was positively correlated with the area of the town, and it was significantly higher in towns localized in agricultural landscape than in towns surrounded by forests. We also found a significant effect of interactions between type of a landscape surrounding a town and residual number of inhabitants on the abundance of pigeons. In the largest towns of the Pomeranian Province, feral pigeons were concentrated mainly in central quarters. In smaller towns, they were noted in central parts or in areas with blocks of flats and even the suburbs. The obtained results suggest that food conditions in small and middle towns may be not sufficient for colonization by pigeons.     

Interspecific differences in photosensitivity between three closely related species of pigeons

It is known from field observations that vernal gonad recrudescence begins in January for the Stock dove, a month later at the end of February for the Wood pigeon, while many town pigeons ( Columba livia ) have active gonads throughout the year.
Photostimulation experiments demonstrate that spermatogenesis can be stimulated in the Stock dove by exposure to an artificial daylength regimeincreasing from 9.1 to 10.8 hours over 28 days. This photoperiod is the approximate equivalent of natural daylength changes occurring from late January onwards at 52° N. The same phototreatment, however, was not stimulatory for the testes of Wood pigeons, which required the equivalent of a March photoperiod. Natural daylength changes occurring in late November and December failed to evoke gametogenetic recovery in Stock dove controls.
The gonads of feral pigeons in full breeding condition were unaffected when the subjects were transferred from full summer photoperiods to those found in midwinter and spermatogenesis was maintained in birds kept under winter daylengths for four months.
The discussion mentions the problem of intraspecific geographical variation in photosensitivity. Scottish Wood pigeons begin their gonad recovery earlier and by March have considerably larger testes than birds in the south of England. Furthermore, they achieve this more advanced condition before the vernal equinox when daylengths are shorter in Scotland than in the south of England.     

Does pigeon homing depend on stimuli perceived during displacement?

Summary In order to test whether stimuli perceived during passive displacement are important for the subsequent homing, pigeons were transported in an apparatus designed to prevent them from receiving relevant information: The experimental birds were continuously rotated quite rapidly (1.5 cps, radial acceleration about 4 g); in addition, they were exposed to an artificial magnetic field and supplied with bottled air. Control birds were transported in open-air cages on top of the van with free view to all sides.Five pairs of releases from equal distances in opposite directions were conducted. Experienced birds were released at distances of about 15, 90, and 300 km from the loft, inexperienced birds at distances of about 180km. In each pair of releases both groups of pigeons were significantly homeward oriented. Neither in initial orientation nor in homing performance nor in the distribution of recoveries were the experimental birds inferior to the controls or in any perceptable way different from them.It is concluded that homing of passively displaced pigeons is not primarily based on information gathered during the outward journey.Abbreviations EP experimental pigeon(s) - CP control pigeon(s) The possibility to maintain our pigeon loft in a building that belongs to the Zoological Institute (Prof. M. Lindauer) of the University of Würzburg is gratefully acknowledged.     

Seasonal changes in some plasma hormones in pigeons: diurnal variation under natural photoperiods with constant or seasonally changing ambient temperature

The diurnal variations of several plasma hormones and free fatty acids (FFA) were studied during periods in summer and winter for pigeons reared either outdoors or indoors. The latter were subjected to constant temperature and naturally varying photoperiods. A significant seasonal variation in the mean daily levels of triiodothyronine (T3), thyroxine (T4), corticosterone (B), lutropin (LH) and FFA was seen in the outdoor birds and in the T4 and B levels of indoor birds. The diurnal variation of hormone levels was generally more pronounced in winter in both groups. Cold ambient temperature significantly decreased the plasma LH level and potentiated the increasing effect of short photoperiod on plasma B level. Diurnal variation of plasma FFA level seems to be under the control of photoperiod, without any effects due to the ambient temperature. No significant correlation was found between FFA and GH concentrations.     

Does avian malaria reduce fledging success: an experimental test of the selection hypothesis

Like many parasites, avian haematozoa are often found at lower infection intensities in older birds than young birds. One explanation, known as the “selection” hypothesis, is that infected young birds die before reaching adulthood, thus removing the highest infection intensities from the host population. We tested this hypothesis in the field by experimentally infecting nestling rock pigeons (Columba livia) with the malaria parasite Haemoproteus columbae. We compared the condition and fledging success of infected nestlings to that of uninfected controls. There was no significant difference in the body mass, fledging success, age at fledging, or post-fledging survival of experimental versus control birds. These results were unexpected, given that long-term studies of older pigeons have demonstrated chronic effects of H. columbae. We conclude that H. columbae has little impact on nestling pigeons, even when they are directly infected with the parasite. Our study provides no support for the selection hypothesis that older birds have lower parasite loads because parasites are removed from the population by infected nestlings dying. To our knowledge, this is the first study to test the impact of avian malaria using experimental inoculations under natural conditions.     

Pigeon Homing: The Navigational Map Developed in Adulthood is Based on Olfactory Information

Homing pigeons raised in a shielded aviary and kept confined until the day of the test releases are not able to navigate even if, once adult, the screens are removed and the birds are exposed to natural winds for a sufficiently long period for map learning. However, pigeons raised in the same condition but, once adult, allowed to perform spontaneous flights around the loft are able to develop navigational abilities which, however, never reach the level of controls. In the present study, we show that the navigational map learned by the adult birds, which had the possibility to perform spontaneous flights, is based on olfactory information.     

Evaluation of the antiparasitic activity of the chitosan-silver nanocomposites in the treatment of experimentally infested pigeons with Pseudolynchia canariensis

This study aimed to evaluate the efficacy of chitosan-silver nanocomposites in the treatment of experimentally infested pigeons with Pseudolynchia canariensis (P. canariensis) with evaluation of different immunological parameters before and after treatment. Therefore, fourteen birds were divided into 2 groups; group1(infested group including 12 birds) which subdivided into 6 sub-groups experimentally infested pigeons 2 pigeons each, and five group of them were treated with chitosan-silver nanocomposites and sub-group number 6 was treated with deltamethrin while, group 2 including two pigeons were kept as control negative ones. P. canariensis flies distributed under the wing and /or under the tail in infested group and these pigeons showed significantly lower RBCs and higher WBCs than that in non-infested pigeons. The cell mediated immune response against experimentally infested pigeons with P. canariensis was studied. P. canariensis infestation in pigeons have a negative impact on pigeon’s blood parameters, increase TNF-α and IL-1β cytokines levels. This study cleared out the role of P. canariensis in the induction of a case of oxidative stress indicated by high level of nitric oxide and malondialdehyde (MDA) with low antioxidant capacity in shape of reduced zinc concentration in the sera of experimentally infested pigeon. Chitosan-silver nanocomposite has a promising effect in the elimination of P. canariensis infestation in pigeons.     

Characterization of baroreflex gain in the domestic pigeon (Columba livia)

Birds have a remarkable capacity to regulate circulation yet little is known about the avian baroreflex. Although both linear regression and curve-fitting techniques are frequently used to assess baroreflex function in mammals, only the former technique has been used in birds. We characterized baroreflex gain in domestic pigeons (Columba livia) and compared gain values derived from applying linear regression to ramp changes in mean arterial pressure (MAP) to values derived from fitting a four-parameter sigmoidal function to steady-state alterations in MAP. We found that, unlike mammals, pigeons do not display circadian patterns in MAP, HR or gain derived from bolus injections of vasoactive drugs. The pressor, but not depressor response, was attenuated by administration of the NMDA-antagonist ketamine, suggesting that central processing of the baroreflex may be similar in birds and mammals despite anatomical differences in arterial baroreceptive zones. Because graded infusions of vasoactive drugs could not consistently produce a plateau in the HR response, fitting data to a sigmoidal curve was difficult. Thus, we propose that variations of the Oxford method and linear regression analysis are superior method to assess baroreflex gain in pigeons than curve fitting.     

The passage and propagation of fecal indicator phages in birds

The presence of F-specific phages in the diet of birds influenced the presence of these fecal indicators in their feces. F-specific phage concentrations in the feces of Canada geese and pigeons, which are normally low, increased greatly the same day coliphage MS2 was added to their diets. F-specific phage concentrations decreased to the original low levels a week after the phage-spiked feed was removed. Geese kept in pens that were cleaned regularly to reduce fecal-oral contamination had significantly lower somatic coliphage concentrations in their feces than wild geese had in their feces. Somatic coliphage concentrations in feces of feral pigeons were typically low with an occasional fecal sample having high numbers of either one of the two types of phages seen in this population of birds. Sometimes many birds had high numbers of only one type of phage in their feces. This lasted only a day and was probably due to fecal contamination of the feeding pans by the pigeons. The degree to which birds are a source of phage indicators of fecal pollution can change in a short period of time. Thus the presence of contaminated feeding sites should be considered before ruling out animals as a possible source of fecal indicators. F-specific phages may be useful tracers for modeling viral transmission and tracking feeding habits in birds. Journal of Industrial Microbiology & Biotechnology (2000) 24, 127–131. Received 06 July 1999/ Accepted in revised form 07 November 1999     

Raphe nucleus and corticorophic activity in pigeons]

Multiple electrolytic lesions were placed in the raphe area of pigeons. Basal plasma corticosterone level (B) was found not to be altered. Stress-induced adrenocortical activation was markedly reduced in raphe lesioned pigeons as compared to controls. Electrical stimulation of the nucleus raphes in permanently implanted, unrestrained and unanesthetized birds induced a significant rise in B. However the magnitude of the response to raphe stimulating was lower (1/2 approximately) and especially later than after hypothalamic stimulation since it paralleled exactly the pattern of stress induced activation.     

Passive Immunization of Pigeons Against Trichomoniasis

SYNOPSIS Nonimmune homing pigeons Columba livia were infected with the Jones' Barn strain of Trichomonas gallinae and subsequently transfused with plasma from acute or chronically infected pigeons harboring one of 3 different strains of T. gallinae. The transfusions were either a single 2 ml dose given one day after inoculation or three 1 ml doses given 0, 5, and 10 days after inoculation. Plasma from pigeons harboring any of the 3 strains was capable of passively immunizing nonimmune birds. All birds which were immunized with plasma from infected pigeons survived until killed at the end of the test period and no visceral lesions were found on necropsy but trichomonads were present in the oropharynx. All controls (untreated or transfused with normal plasma) died of visceral trichomoniasis.
Immune plasma produced some lysis of trichomonads in vitro, and inhibition of motility and vacuolization occurred in some of the non-lysed organisms. The overall lytic activity in vitro affected less than 10% of the suspended trichomonads.