Pigeon Homing: The Orientation of Young Birds that had been Prevented from Seeing the Sun

To test whether the sun is an essential factor for the development of a functioning orientation system in birds, a group of young pigeons was raised as ‘No-Sun’-birds. They were not allowed to see the sun, and they were released to fly around their loft only under total overcast. The control group had an equal number of opportunities to fly under overcast plus additional flights under sun. When released as untrained birds under solid cloud cover, the ‘No-Sun’-birds were significantly oriented, whereas the controls were not. Small magnets glued between the wings (north toward the head) reversed the ‘No-Sun’-birds' orientation, indicating they used a magnetic compass. These findings show that the orientation system can develop without information from the sun. Differences in the orientation behavior of the ‘No-Sun’-birds and normally raised young pigeons are discussed.     

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.     

Pigeon Homing in the Meteorological and Solar-geomagnetic Environment: what Pigeon Race Data say

In this statistical analysis, the fastest 25% of homing speeds in 5955 races conducted in West Germany on 194 days in 1973–1990 and the return rates in 18 pigeon races held in 1932–1957 in Italy were examined with respect to distance, cloud cover, wind, sferics, solar and magnetic variables. 1. Under sun, the speeds rapidly increased with distance from 120 up to 240 km and slowly declined beyond 240 km. 2. Correlations between race and wind speeds were maximized by rotating clockwise and extrapolating the local surface wind linearly according to the average wind profile (difference between the mean surface and mean 900 m-height wind vector). The best predictors indicated the speeds of the winds the birds encountered aloft, which were blowing at lower heights in headwinds than in tailwinds. 3. The air speeds correlated negatively with the effective wind forces roughly in agreement with Pennycuick's theory of bird flight. 4. Rates of atmospherics (2.8–38 kHz, 0.02–0.4V/m recorded in Berlin) correlated negatively with the speeds. 5. Under sun, the difference between the fastest and slowest speed correlated with sunspot numbers (R) in a very active solar cycle (1979–1987), but not in the preceding and following cycles which had lesser activity. 6. Under sun, the speeds correlated directly or indirectly with solar and magnetic activity (25% and 21 % of the samples per year and per homeward direction, respectively), but did so only in 9.9% and 6.9% of samples (respectively) when races to the same home area were sampled over the years. Under overcast, most of the correlations were negative. 7. While magnetic disturbances appeared to coincide with higher speeds inconsistently under sun, they appeared to interfere with the speeds consistently under overcast. Under sun, the seasonal median speeds, unlike the daily median ones, correlated negatively with magnetic activity. 8. Hourly variations of the geomagnetic field components correlated negatively with the speeds in 1973–1975 in western, but positively in eastern and southern, homeward directions. 9. The return rates in Italian pigeon races were best predicted by hourly variations of the horizontal intensity of the regional geomagnetic field and second-best by sunspot numbers. 10. The significance of the results for understanding the role of the meteorological and solar-magnetic environment in pigeon homing is discussed.     

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.     

空气污染对信鸽比赛个体归巢速度的影响

空气污染作为一种有害的环境因素,对人类及动物的生理、心理均有影响.在鸟类中,信鸽(Columba livia)是研究空气污染影响的理想模型.为探究空气污染的行为学效应,通过收集并筛选2018和2019年成都市信鸽协会春秋两个季节举办的64场赛事共285羽参赛5场及以上的信鸽不同空距等级下的归巢速度,利用混合线性模型分析...     

Initial Orientation of Deer Mice (Peromyscus maniculatus) released on Snow in Homing Experiments

Im Winter 1966–67 wurden 19 Peromyscus maniculatus ein- oder mehrmals auf 100–500 m außerhalb ihrer Heimbezirke versetzt. Sie wurden bei Nacht in einem flachen mit Schnee bedeckten Acker freigelassen; die menschlichen Spuren waren symmetrisch um die Freilassungsplätze verteilt. Unter diesen Bedingungen verließen die Mäuse, die im Heimfinden erfolgreich waren, den Freilassungsort in die Heimrichtung ± 90°. Dieser Befund stützt die Hypothese, daß die von Lindenlaub (1955, 1960) und Bovet (1960) nachgewiesene potentielle Anfangsorientierung von verfrachteten Mäusen zum Heimplatz durch eine Orientierung zu asymmetrisch um die Tiere verteilten Deckungen (z. B. Mäuselöcher und Wechsel) in den ?üblichen” Feldsituationen vorübergehend maskiert oder aufgehoben wird.     

Temporal and Contextual Consistency of Leadership in Homing Pigeon Flocks

Organized flight of homing pigeons (Columba livia) was previously shown to rely on simple leadership rules between flock mates, yet the stability of this social structuring over time and across different contexts remains unclear. We quantified the repeatability of leadership-based flock structures within a flight and across multiple flights conducted with the same animals. We compared two contexts of flock composition: flocks of birds of the same age and flight experience; and, flocks of birds of different ages and flight experience. All flocks displayed consistent leadership-based structures over time, showing that individuals have stable roles in the navigational decisions of the flock. However, flocks of balanced age and flight experience exhibited reduced leadership stability, indicating that these factors promote flock structuring. Our study empirically demonstrates that leadership and followership are consistent behaviours in homing pigeon flocks, but such consistency is affected by the heterogeneity of individual flight experiences and/or age. Similar evidence from other species suggests leadership as an important mechanism for coordinated motion in small groups of animals with strong social bonds.     

Homing in Harvester Termites: Evidence of Magnetic Orientation

Colonies of Trinervitermes geminatus (Wasman) build a network of forked foraging trails. Homing workers choose, with few exceptions, those tracks at the forks of the pheromone trail network that lead direct to the nest. Assessments show that these workers are also able to distinguish between the homeward and outward direction along an unbranched trail. Experiments involving the alteration of the local natural magnetic field by means of a weak permanent magnet provide evidence that the termites recognise the home direction by means of magnetoreception.     

Attempts to Determine the Roles of Visual and Olfactory Inputs in Initial Orientation and Homing of Pigeons over Familiar Terrain

The role of familiar visual landmarks in pigeon homing is still unsettled. If they are involved, they must be thought to be utilized in parallel with olfactory signals. In order to recognize the effectiveness of either one of the input channels separately, vision and olfaction, it is therefore necessary to interfere with both of them. Pigeons were temporarily deprived of image vision by spectacles made of translucent white paper, producing a condition called V^- as compared with the largely unimpaired condition V⁺. Access to olfactory signals was temporarily prohibited by charcoal filters before release and nasal anaesthesia upon release, resulting in condition O^- versus unimpaired smelling of natural air in O⁺. Prior to the test releases, all the participating pigeons had been made familiar with the two or four test sites (and with other sites in the area) by training flights. According to decreasing levels of initial homeward orientation and homing performance, the four combinations of treatments are to be arranged in the following order: V⁺O⁺, V⁺O^-, V^-O⁺, V^-O^-. In the last type, no trace of initial homeward orientation remained, indicating that at least one of the two input channels need be functional to enable home-related orientation. Over well known terrain, either alone seems to be more or less sufficient. The results are indicative but not definitely conclusive. Effects of visual impairment on behavioural activities in general cannot clearly be separated from orientation-specific effects. Therefore, and because many pigeons refuse to fly in V^- condition or fail to provide useful data, we stopped applying this method.     

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.     

Experience Based Use of Landmark and Vector Based Orientation During Homing by the Ant Formica cunicularia (Hymenoptera: Formicidae)

Homing paths of Formica cunicularia foragers from an artificial food reward were analyzed on a familiar terrain and in displacement experiments on a familiar and an unfamiliar terrain. Foragers were tested either when relatively new to a foraging route (untrained group) or after a day’s experience with it (trained group). Untrained foragers followed direct homing paths to the nest site when tested in the familiar terrain but followed tortuous paths when displaced to the unfamiliar terrain. Trained foragers behaved similarly to untrained ones when tested from the food reward to the nest site in the familiar terrain but their behavior changed in displacements. Irrespective of the familiarity of the displacement site, these foragers followed paths taking them to the expected nest sites. The results showed that foragers did not rely on chemical cues for homing and revealed that untrained foragers disregarded path integration and were directed to the nest site when it is in their visual panorama. On the contrary, trained foragers may have relied on path integration on familiar and unfamiliar terrain. The results also demonstrated that experience greatly affected the preferential use of visual and vector based cues by foragers during homing.     

Short-range Homing in Fiddler Crabs (Ocypodidae, Genus Uca): A Homing Mechanism not Based on Local Visual Landmarks

This field study investigated the spatial strategies and homing ability of two East African fiddler crabs, Uca lactea annulipes and Uca vocans hesperiae, using various experimental procedures. A clear-cut spatial segregation between the two species was observed, with U. l. annulipes occupying areas even a few centimetres above U. v. hesperiae . Females of both species were extremely faithful to their holes while the males exhibited behavioural differences. U. l. annulipes males were quite faithful to their holes; in contrast, U. v. hesperiae males, during a single low tide, visited several holes which they did not defend. Two displacement experiments were conducted in order to identify the stimuli that fiddler crabs use in their homing. In the 'dislocation experiment', the crabs were moved (by hand) 1 or 2 m away from their refuge and released. None of these crabs returned to its burrow and, moreover, the initial directions they followed were not homeward orientated. In the 'translation experiment', the crabs were passively translated while actively feeding. When the crabs attempted to go 'home' after the translation, they darted along a straight path that led them to points that would have corresponded to their homes if the translation had not taken place. After this first response crabs then commenced searching strategies that led half of them home. Short-range homing seems to depend strongly on information actively gathered during the outward journey, other than local visual landmarks.     

Optimising Homing Endonuclease Gene Drive Performance in a Semi-Refractory Species: The Drosophila melanogaster Experience

Homing endonuclease gene (HEG) drive is a promising insect population control technique that employs meganucleases to impair the fitness of pest populations. Our previous studies showed that HEG drive was more difficult to achieve in Drosophila melanogaster than Anopheles gambiae and we therefore investigated ways of improving homing performance in Drosophila. We show that homing in Drosophila responds to increased expression of HEGs specifically during the spermatogonia stage and this could be achieved through improved construct design. We found that 3′-UTR choice was important to maximise expression levels, with HEG activity increasing as we employed Hsp70, SV40, vasa and βTub56D derived UTRs. We also searched for spermatogonium-specific promoters and found that the Rcd-1r promoter was able to drive specific expression at this stage. Since Rcd-1 is a regulator of differentiation in other species, it suggests that Rcd-1r may serve a similar role during spermatogonial differentiation in Drosophila. Contrary to expectations, a fragment containing the entire region between the TBPH gene and the bgcn translational start drove strong HEG expression only during late spermatogenesis rather than in the germline stem cells and spermatogonia as expected. We also observed that the fraction of targets undergoing homing was temperature-sensitive, falling nearly four-fold when the temperature was lowered to 18°C. Taken together, this study demonstrates how a few simple measures can lead to substantial improvements in the HEG-based gene drive strategy and reinforce the idea that the HEG approach may be widely applicable to a variety of insect control programs.     

Improving Community Based Pediatric Residencies by Local Affiliation: The Phoenix Experience

Community hospital graduate medical education programs have been judged deficient in several areas when compared with university programs. Generally community programs are smaller, they have a greater percentage of foreign house officers and unfilled house staff positions, and their graduates do less well on specialty board examinations. Difficulties may exist in offering a balanced and broad-based educational exposure. Four separate pediatric residencies in Phoenix became affiliated in 1972. The traditional deficiencies have been overcome, and a very popular and well-balanced program has ensued. Additionally, wasteful duplication has been avoided. Disadvantages have included complex scheduling and loss of continual close contact with house officers. Assigning patients to residents for continuity of care has been difficult. Experiences gained in this amalgamation may well apply to other hospitals facing similar problems. Local consortiums, such as this, fit well into university affiliated programs or statewide organizations.     

Partnering for Greater Success: Local Stakeholders and Research in Tropical Biology and Conservation

Local communities are important stakeholders in resource management and conservation efforts, particularly in the developing world. Although evidence is mixed in suggesting that these resident stakeholders are optimal forest stewards, it is highly unlikely that large tracts of tropical forests will be conserved without engaging local people who depend on them daily for their livelihoods. Stakeholders, who reside in biodiverse ecosystems like tropical forests, are the largest direct users and ultimate decision-makers of forest fate, can be important investors in conservation, harbor local ecological knowledge that complements Western science and frequently have long-term legitimate claims on lands where they reside. Research partnerships with local stakeholders can increase research relevance, enhance knowledge exchange and result in greater conservation success. Different phases of the research cycle present distinct opportunities for partnership, with flexibility in timing, approaches and strategies depending on researcher and local stakeholder needs and interests. Despite being the last step in the research process, dissemination of results can be the best starting point for researchers interested in experimenting with local stakeholder engagement. Still, tropical biologists might not choose to partner with local people because of lack of institutional rewards, insufficient training in stakeholder engagement, insecure research infrastructure in community settings, and time and funding limitations. Although not appropriate in all cases and despite significant challenges, some biological scientists and research institutions have successfully engaged local stakeholders in the research process, proving mutually beneficial for investigators and local people alike and resulting in important innovations in tropical biology and conservation.     

Pigeon homing: Further experiments on shielded lofts

• 1.1. Two series of experiments were performed by rearing homing pigeons in two corridor-lofts in each of which they could perceive winds from one direction only (340 and 160° in the first series, 250 and 70° in the second one).
• 2.2. In the first series the two groups of birds were differently, but not homeward, oriented.
• 3.3. In the second series the birds were homeward oriented only when released from sites lying along the directions from which they could sense wind at the home loft.

     

Homing in German Cockroaches, Blattella germanica (L.) (Insecta: Dictyoptera): Multi-Channelled Orientation Cues

Cockroaches use navigational cues to elaborate their return path to the shelter. Our experiments investigated how individuals weighted information to choose where to search for the shelter in situations where path integration, visual and olfactory cues were conflicting. We showed that homing relied on a complex set of environmental stimuli, each playing a particular part. Path integration cues give cockroaches an estimation of the position of their goal, visual landmarks guide them to that position from a distance, while olfactory cues indicate the end of the path. Cockroaches gave the greatest importance to the first cues they encountered along their return path. Nevertheless, visual cues placed beyond aggregation pheromone deposits reduced their arrest efficiency and induced search in the area near the visual cues.