Departure Decisions Research Articles

Departure Decisions: Exit Survey of Family Medicine Residency Directors.

Program director (PD) tenure, continuity, and stability may enhance residency program quality, yet many PDs do not stay long in their positions. No prior study has taken a comprehensive census of departing PDs to determine reasons for leaving the role. This study aimed to survey all exiting family medicine (FM) PDs to identify decision factors contributing to their departure. From October 2021 to October 2022, we sent a web-based exit survey to all departing FM PDs. The survey asked departing PDs to rate the strength of 36 factors in the decision to exit the PD role in terms of job satisfaction, accomplishments, career choices, workload, preparation, expectations, and support. We used the Fisher exact test to assess all 36 decision factors and PD characteristics for significant associations with shorter or longer PD tenures. PDs submitted 73 surveys out of 109 invitations (67.0% response). We analyzed 68 with complete data. The median PD tenure was 5.6 years (mean 6.9 years). Most respondents (66/68, 97.1%) identified three or more strong factors in their decision to leave. The strongest factors reflected stable residency programs, an established succession plan, a desire for more personal/family time, and a sense that the time was right. PDs with tenures longer than 3 years were more likely to have completed the National Institute for Program Director Development (P=.001). PDs leave the position for multiple reasons, often positive, and not necessarily due to lack of support and preparation. Further exploration of decision factors may inform strategies to support PDs in their positions.

Trade Union Officers’ Departure Decisions: A Comparative Study

Trade Union Officers’ Departure Decisions: A Comparative Study

Time of year and weather influence departure decisions of sandhill cranes at a primary stopover

The Rocky Mountain Population (RMP) of greater sandhill cranes uses a key stopover area, the San Luis Valley (SLV) in Colorado. Parameters of migration phenology can differ between autumn and spring and are affected by weather and environmental factors. We hypothesized that sandhill cranes in the SLV would have a longer stopover duration in autumn than in spring, and that wind assistance, crosswinds, temperature change, barometric air pressure, and surface water area would influence persistence probability. We used data from sandhill cranes fitted with transmitters that spanned autumn and spring, 2015-2022. We used an open robust design mark-recapture model to estimate stopover duration, arrival probability, and persistence probability. We examined the effects of weather and surface water on the persistence probability for 106 sandhill cranes in the SLV. Stopover duration was longer in autumn than in spring and had higher variability across years. Arrival probability to the SLV peaked on 13 October in autumn and 21 February in spring. Persistence probability declined around mid-December in autumn and mid-March in spring. We found that several weather covariates influenced persistence in both seasons. In autumn, sandhill cranes departed the SLV with higher tailwinds, lower crosswinds, and higher surface water availability. In spring, sandhill cranes departed the SLV with lower crosswinds and higher barometric air pressure at the surface and higher wind speeds at altitudes of about 3,000 m. The effect of wind speed was stronger later in the spring. Given the lower variability of arrival and persistence probability and shorter stopover duration in spring compared to autumn, we suspect that RMP sandhill cranes are using a time-minimization strategy during spring. However, given the use of supportive winds and weather conditions ideal for soaring, RMP sandhill cranes appear to be using strategies that save energy in both seasons. Our study identifies the optimal timing of water management and surveys for RMP sandhill cranes and confirms that weather influences their persistence. Understanding differences in migration patterns between seasons and the factors that influence persistence at stopover sites will also be important for anticipating phenological impacts from climate change and land use alterations.

Determinants of spring migration departure dates in a New World sparrow: Weather variables reign supreme.

Numerous factors influence the timing of spring migration in birds, yet the relative importance of intrinsic and extrinsic variables on migration initiation remains unclear. To test for interactions among weather, migration distance, parasitism, and physiology in determining spring departure date, we used the Dark-eyed Junco (Junco hyemalis) as a model migratory species known to harbor diverse and common haemosporidian parasites. Prior to spring migration departure from their wintering grounds in Indiana, USA, we quantified the intrinsic variables of fat, body condition (i.e., mass ~ tarsus residuals), physiological stress (i.e., ratio of heterophils to lymphocytes), cellular immunity (i.e., leukocyte composition and total count), migration distance (i.e., distance to the breeding grounds) using stable isotopes of hydrogen from feathers, and haemosporidian parasite intensity. We then attached nanotags to determine the timing of spring migration departure date using the Motus Wildlife Tracking System. We used additive Cox proportional hazard mixed models to test how risk of spring migratory departure was predicted by the combined intrinsic measures, along with meteorological predictors on the evening of departure (i.e., average wind speed and direction, relative humidity, and temperature). Model comparisons found that the best predictor of spring departure date was average nightly wind direction and a principal component combining relative humidity and temperature. Juncos were more likely to depart for spring migration on nights with largely southwestern winds and on warmer and drier evenings (relative to cooler and more humid evenings). Our results indicate that weather conditions at take-off are more critical to departure decisions than the measured physiological and parasitism variables.

Experimental changes in food and ectoparasites affect dispersal timing in juvenile burrowing owls.

Natal dispersal is a key demographic trait that affects population dynamics, and intraspecific variation in dispersal affects gene flow among populations and source-sink dynamics. However, relatively little is known about the selective pressures and trade-offs that animals face when departing their natal area due to the logistical difficulties associated with monitoring animals during this critical life stage. We used a randomized block design to examine the selective pressure that influence dispersal timing in juvenile burrowing owls (Athene cunicularia) by experimentally altering both food and ectoparasites at 135 nests. We also examined the effects of local food abundance, ectoparasite loads, and parental departure on natal dispersal timing. Juvenile burrowing owls varied widely in natal dispersal timing, and phenotypic plasticity in dispersal timing was evident in juvenile owls' response to our experimental treatments, local conditions, and their parents' departure from the natal area. Moreover, juveniles responded differently than their parents to experimental manipulation of food and ectoparasite loads. Juveniles typically dispersed shortly after their parents departed the natal area, but delayed dispersing more than 2 weeks after parental departure if they did not receive experimental food supplements during a low-food year. In contrast, the experimental food supplements did not affect the migratory departure decisions of adult owls in either year. Juveniles at nests treated for ectoparasites initiated dispersal at a younger age (and prior to adults in the high-food year) compared to juveniles at control nests. In contrast, parents at nests treated for ectoparasites departed later than parents at control nests. Our results suggest that unfavorable conditions (low food or high ectoparasite loads) caused juveniles to delay dispersal, but prompted adults to depart sooner. Our results highlight the extent of intraspecific variation in natal dispersal timing, and demonstrate that ecological conditions affect dispersal decisions of parents and offspring differently, which can create important trade-offs that likely affect life history strategies and responses to climatic changes.

The urge to breed early: Similar responses to environmental conditions in short‐ and long‐distance migrants during spring migration

AbstractBirds migrating different distances experience different temporal, energetic, physiological, and physical constraints throughout migration, which is reflected in their migration strategy. Consequently, we predict different behavioral decisions to similar environmental cues between short‐ and long‐distance migrants, which has been documented for autumn migration. Here, we focus on the question whether trade‐off decisions regarding departure, routing, and landing when alternating between migratory endurance flights and stopovers also differ during spring migration. As early arrivals at the breeding grounds should be ultimately favored regardless of migration distance, selection may favor more similar behavioral decisions in spring than in autumn. We radio‐tagged short‐ and long‐distance migratory songbirds at stopover sites along the German North Sea coast during spring and automatically tracked their migratory behavior using a large‐scale network of receiver stations. Once departed, birds could either cross the sea or detour along the coast. We corrected for spatially biased detection data, using a hierarchical multistate model to assess how birds respond to variation in environmental conditions in their day‐to‐day departure decisions and route selection. The day‐to‐day departure probability was higher in long‐distance migrants independently of the routing decision. Irrespective of migration distance, all species more likely departed under light winds and rainless conditions, while the influence of air pressure change and relative humidity was species‐specific. By accounting for detection probabilities, we estimated that about half of all individuals of each species crossed the sea but did not find differences between short‐ and long‐distance migrants. Offshore flights were more likely when winds blew offshore and began earlier within the night compared with onshore flights. Our results suggest that selection more similarly affects birds of different migration distances in spring than in autumn. These findings put the focus toward how ultimate mechanisms may shape departure and routing decisions differently between migration seasons.

Quorum decision making coordinates group departure decisions in Eurasian oystercatchers, Haematopus ostralegus

Prey species that form groups gain a range of benefits from associating with conspecifics, including access to social information. Groups typically coordinate collective movement through local interactions, where individuals copy their nearest neighbours' behaviour to generate group level decisions. However, individuals in a group may not always make ‘correct’ decisions, and blind copying of behaviour can lead to the spread of poor information and maladaptive cascades. To impede the spread of poor information, many animals that form groups have developed information-dampening mechanisms such as consensus decision making through the quorum response. In this study we monitored flocks of roosting Eurasian oystercatchers with a view to understanding the mechanics of group departure decisions and to test for the presence of a quorum response. Nearing high tide, oystercatchers would leave the roosting site en masse, where the timing of departure of many individuals was coordinated. Coordinating the timing of mass departures was a complex task as single birds and small groups frequently joined and departed from the roosting site, meaning individuals had to decide which departures to copy and which to ignore. Individual oystercatchers were more likely to depart within 10 s of another bird if they were closer together in the group, suggesting that departure information may be transferred locally between neighbouring birds. While single departures were very common, most individuals departed in groups of 10 or more, showing that single departures were a relatively weak departure cue and were frequently ignored by the rest of the group. The probability of an individual joining a departure event was higher with increasing departure group size in a nonlinear (sigmoidal) relationship. This trend is consistent with a quorum response with the propensity to copy the departure of groupmates sharply increasing at a quorum threshold of about 10 birds.

Beyond Performance: Does Assessed Potential Matter to Employees’ Voluntary Departure Decisions?

ABSTRACTFirms are increasingly implementing performance–potential assessment systems, whereby supervisors evaluate employees’ current performance and future‐oriented potential (i.e., promotion prospects). Whether retention is greatest for high performance–high potential (HiPo) employees under such a system is an empirical question—while the “promise” of a promotion may aid retention, these employees likely face attractive outside options. Using data from a multinational firm, I find that HiPos generally depart at a lower rate than lower performing non‐HiPos. Among shorter tenured employees, I find the strongest evidence that potential matters to departures, above and beyond performance. In several instances, the rate of departure is lower when assessed potential is higher, holding performance constant. This is the case both among higher performers, where high potential leads to HiPo status, and among lower performers where high potential affords no such status. My findings suggest that HiPo status and potential ratings may help in facilitating employees’ early sorting decisions.

Songbirds initiate migratory flights synchronously relative to civil dusk

BackgroundEach spring and fall billions of songbirds depart on nocturnal migrations across the globe. Theory suggests that songbirds should depart on migration shortly after sunset to maximize their potential for nightly flight duration or to time departure with the emergence of celestial cues needed for orientation and navigation. Although captive studies have found that songbirds depart during a narrow window of time after sunset, observational studies have found that wild birds depart later and more asynchronously relative to sunset than predicted.MethodsWe used coded radio tags and automated radio-telemetry to estimate the time that nearly 400 individuals from nine songbird species departed their breeding or wintering grounds across North America. We also assessed whether each species was most likely beginning long-distance migratory flights at departure or instead first making non-migratory regional flights. We then explored variation in nocturnal departure time by post-departure movement type, species, age, sex, and season.ResultsWe found that 90% of individuals from species that were likely initiating long-distance migratory flights departed within 69 min of civil dusk, regardless of species, season, age, or sex. By contrast, species that likely first made non-migratory regional movements away from the migratory destination departed later and more asynchronously throughout the night. Regardless of post-departure movement type, 98% of individuals departed after civil dusk but otherwise showed no preference in relation to twilight phase.ConclusionsAlthough the presence of celestial orientation cues at civil dusk may set a starting point for departure each night, the fact that species likely beginning long-distance migration departed earlier and more synchronously relative to civil dusk than those first making non-migratory regional movements is consistent with the hypothesis that departing promptly after civil dusk functions to maximize the potential for nightly flight duration and distance. By studying the onset of migration, our study provides baseline information about departure decisions that may enhance our understanding of departure timing throughout migration.

Local weather and endogenous factors affect the initiation of migration in short‐ and medium‐distance songbird migrants

Migratory birds employ a variety of mechanisms to ensure appropriate timing of migration based on integration of endogenous and exogenous information. The cues to fatten and depart from the non‐breeding area are often linked to exogenous cues such as temperature or precipitation and the endogenous program. Shorter distance migrants should rely heavily on environmental information when initiating migration given relatively close proximity to the breeding area. However, the ability to fatten and subsequently depart may be linked to individual circumstances, including current fuel load and body size. For early and late departing migrants, we investigate effects of temperature, precipitation, lean body mass, fuel load and day of year on the initiation of migration (i.e. fuel load and departure timing) from the non‐breeding region by analyzing 21 years of banding data for four species of short‐ and medium‐distance migrants. Temperatures at the non‐breeding area were related to temperatures at potential stopover areas. Despite local cues being predictive of conditions further north, the amount variation explained by local weather conditions in our models differed by species and temporal period but was low overall (< 33% variation explained). For each species, we also compared lean body mass and fuel load between early and late departing migrants, which showed mixed results. Our combined results suggest that most individuals migrating short or medium distances in our study did not time the initiation of migration with local predictive cues alone, but rather other factors such as lean body mass, fuel load, day of year, which may be a proxy for the endogenous program, and those beyond the scope of our study also influenced the initiation of migration. Our study contributes to understanding which factors influence departure decisions of short‐ and medium‐distance migrants as they transition from the non‐breeding to the migratory phase of the annual cycle.

Flower patterns improve foraging efficiency in bumblebees by guiding approach flight and landing

Abstract Colourful patterns on flowers are thought to benefit both pollinators and the plants they visit, by increasing the plants' pollination success via an increased foraging efficiency of the pollinators. This increased efficiency is assumed to result from a guidance effect of the flower patterns, correspondingly termed ‘nectar guides’, which indicate the position of the nectary to visiting pollinators, thus reducing their flower handling time. Although it is well established that flower patterns play an important role in flower choice, the mechanisms by which they improve the foraging efficiency of flower‐visiting insects remain poorly understood. In this study, we quantified the contributions of patterns to all phases of flower interaction in the buff‐tailed bumblebee Bombus terrestris. We analysed the bees' flight paths, as well as landing positions and walking tracks on artificial flowers with different pattern types. We reveal that flower patterns reduced the overall flower handling time of the bees by up to 30%, by guiding their approach flight, landing positions and departure decisions. Surprisingly, we observed no improvement in nectary discovery time after the bees landed on the flower. Since we tested experienced foragers, which represent the majority of insect pollinators active in nature, the newly described nectary‐independent guidance effects of flower patterns are of high ecological relevance. Read the free Plain Language Summary for this article on the Journal blog.

Beyond Performance: Does Assessed Potential Matter to Employees’ Voluntary Departure Decisions?

Beyond Performance: Does Assessed Potential Matter to Employees’ Voluntary Departure Decisions?

Do departure and flight route decisions correlate with immune parameters in migratory songbirds?

Abstract Many songbirds migrate twice a year to exploit seasonally available resources. These journeys are energetically demanding and energy reserves of these small birds are limited. Accordingly, most of the time migrating is spent during stopovers that serve to rest, replenish resources and recover. While external influences, like prevailing weather conditions and resource availability, are well studied with regard to stopover behaviour and departure decisions, studies on how birds' individual physiological condition and stopover decisions may be linked are scarce. We used a large‐scale radio‐telemetry network covering the German Bight (SE North Sea) to study how birds' immunological constitution at stopover may correlate with departure and flight behaviour in five species of short‐ to medium‐distance migratory songbirds. We measured markers of the innate (bacterial killing activity, lysozyme concentration, natural antibodies and complement titres) and acquired immune function (immunoglobulin Y) in the birds' plasma. After sampling, we tracked the birds' behaviour in terms of stopover duration as well as flight routes and flight distances within the telemetry network after departure. We found that stopover durations were positively related to natural antibodies and immunoglobulin Y across species and to the bacterial killing activity solely in song thrushes in spring, while no relations became apparent in fall. Flight distances were linked positively to immunoglobulin Y concentrations in both spring and fall, though not in all of the investigated species. Coastal and offshore‐oriented routes were taken independent of the birds' immune status. Our study for the first time shows that migratory behaviour of songbirds in the wild is correlated with their immune status, not only during but also beyond stopover. Furthermore, birds with increased complement titres and Immunoglobulin Y concentrations, either due to recent infection or greater investment in their immune function, took additional time at their stopover sites, probably to reach their breeding grounds in good condition. During the less time‐constrained fall season, stopovers were generally prolonged, independent from the birds' immune status and any delays taken to improve immune status are most likely not detrimental in terms of fitness. Read the free Plain Language Summary for this article on the Journal blog.

Leaving the Institution or Leaving the Academy? Analyzing the Factors that Faculty Weigh in Actual Departure Decisions

Leaving the Institution or Leaving the Academy? Analyzing the Factors that Faculty Weigh in Actual Departure Decisions

The A to E (ABCDE) Pit Crew Model: A Novel Approach to Team Based Care of Critical Patients in the Prehospital Setting.

This study aimed to evaluate the effectiveness of a Pit Crew intervention to improve team dynamics and time to performance of critical actions in a prehospital critical care scenario. The primary outcome was successful completion of critical actions and time to completion of these critical actions. Secondary outcomes included effectiveness of communication and overall team functioning. The study was conducted with a fire-based Emergency Medical Services (EMS) system with 233 paramedics and 115 Emergency Medical Technicians (EMT). Eight EMS crews comprised of five members each were randomly selected and assigned to either the intervention or the control group. The intervention group (n=20) watched a thirty-minute video prior to the training describing the "Pit Crew Approach;" the control group (n=20) did not watch the video. Each crew was given the same simulation scenario of a pediatric patient that had overdosed on a beta-blocker. Completion of predetermined critical tasks were noted and timestamped. A survey was administered to the participants following the training to assess team dynamics and level of confidence. Three outcomes were statistically significant between the two arms: The interventional group felt they themselves had a more defined role in the resuscitation in comparison to the non-interventional group (p= 0.021). The interventional group also felt that their team members had a clearer and more defined role than the nonintervention group (p= 0.018). The interventional group also felt more confident managing a beta blocker overdose than the nonintervention group (p.007). The only statistically significant secondary outcome finding was in scene departure decision: the interventional arm spent more time on-scene (p=0.031). Of note, the non-intervention group missed performing tasks more often than the interventional group and team leaders of these groups often performed task(s) while also directing the patient care. The Pit Crew model was developed to optimize communication and team function. Our data identified that a formal instruction of the pit crew approach to a critical care scenario improved comfort in patient care. Future studies are needed evaluate other methods of training and the effects of continued formal pit-crew training over time.

Mass gain and stopover dynamics among migrating songbirds are linked to seasonal, environmental, and life-history effects

Abstract During migration, birds must stopover at refueling sites to replenish energy stores, with the rate of refueling linked to stopover length, migration speed, and the timing of critical life stages, such as breeding. Under optimal migration theory, birds are expected to maximize fuel intake and minimize stopover length (the time minimization hypothesis). Within a multi-species framework, we demonstrate that time minimization behavior is context-dependent, as refueling rate, stopover length, and departure decisions vary between seasons, among species with different ecological traits (e.g., diet and migration distance), and in response to density-dependent factors and prevailing environmental conditions. Using long-term banding data (10 years) from southwestern British Columbia, Canada, we investigated the ecological processes shaping stopover dynamics among 5 warbler (Parulidae) and 5 sparrow species (Passerellidae). Specifically, we assessed variation in fuel deposition rates (FDRs) as well as the associations between mass gain, stopover length, and departure probability. FDR was greater in insectivorous warblers during spring migration and in species migrating long distances. FDR responded positively to temperature and habitat productivity, but negatively to precipitation events, particularly for insectivorous, long-distance migrants during spring migration. Similarly, density-dependent refueling rate was only observed in insectivores and long-distance migrants during spring migration, where higher densities of foliage-gleaning insectivores were associated with a lower FDR. Stopover duration was more closely associated with body condition upon arrival and subsequent mass gain than direct environmental effects, especially during northward spring migration, providing support for time minimization and a mass threshold influencing departure decisions. These results highlight that refueling rates and stopover quality vary among species depending on their life-history strategies, with particular implications for long-distance, migratory insectivores, which may be most susceptible to climate shifts.

Experimental ghrelin administration affects migratory behaviour in a songbird

Twice a year, billions of birds take on drastic physiological and behavioural changes to migrate between breeding and wintering areas. On migration, most passerine birds regularly stop over along the way to rest and refuel. Endogenous energy stores are not only the indispensable fuel to complete long distance flights, but are also important peripheral signals that once integrated in the brain modulate crucial behavioural decisions, such as the decision to resume migration after a stopover. A network of hormones signals metabolic fuel availability to the brain in vertebrates, including the recently discovered gut-hormone ghrelin. Here, we show that ghrelin takes part in the control of migratory behaviour during spring migration in a wild migratory passerine. We manipulated blood concentrations of ghrelin of 53 yellow-rumped warblers (Setophaga coronata coronata) caught during stopover and automatically radio-tracked their migratory behaviour following release. We found that injections of acylated and unacylated ghrelin rapidly induced movements away from the release site, indicating that the ghrelin system acts centrally to mediate stopover departure decisions. The effects of the hormone manipulation declined within 8 h following release, and did not affect the overall rate of migration. These results provide experimental evidence for a pivotal role of ghrelin in the modulation of behavioural decisions during migration. In addition, this study offers insights into the regulatory functions of metabolic hormones in the dialogue between gut and brain in birds.

Fat Stores and Antioxidant Capacity Affect Stopover Decisions in Three of Four Species of Migratory Passerines With Different Migration Strategies: An Experimental Approach

During migratory stopovers, birds must make decisions about when and where to travel and these decisions are likely contingent on their fuel stores, food availability, and antioxidant capacity as well as seasonal changes in key environmental factors. We conducted a field experiment on an offshore stopover site (Block Island, Rhode Island, United States: 41°130N, 71°330W) during autumn migration to test the hypothesis that birds with greater fuel stores and non-enzymatic antioxidant capacity have shorter stopovers than lean birds with low antioxidant capacity, and to determine the extent to which this depends on migration strategy. We used a 2 × 2 factorial field experiment (two levels each of available food and dietary polyphenols) with four species of songbirds kept in captivity for 3–5 days to produce experimental groups with different fuel stores and antioxidant capacity. We attached digital VHF transmitters to assess stopover duration and departure direction using automated telemetry. Non-enzymatic antioxidant capacity increased during refueling for Red-eyed Vireos (Vireo olivaceus) and Blackpoll Warblers (Setophaga striata) fedad libdiets, and forad libfed Hermit Thrushes (Catharus guttatus) supplemented with polyphenols, but not for Yellow-rumped Warblers (Setophaga coronata coronata). Glutathione peroxidase (GPx) decreased during captivity and was influenced by dietary treatment only in Red-eyed Vireos. Oxidative damage decreased during captivity for all species except Yellow-rumped Warblers. Stopover duration was shorter for Vireos and Blackpolls fedad libas compared to those fed maintenance.Ad libfed Hermit Thrushes supplemented with polyphenols had shorter stopovers than those fedad lib, as did thrushes fed at maintenance and supplemented with polyphenols compared with those fed at maintenance alone. There was no influence of condition on stopover duration for Yellow-rumped Warblers. Departure direction was not strongly related to condition, and birds primarily reoriented north when departing Block Island. Thus, fat stores and oxidative status interacted to influence the time passerines spent on stopover, and condition-dependent departure decisions were related to a bird’s migration strategy. Therefore, seasonal variation in macro- and micro-nutrient resources available for refueling at stopover sites can affect body condition and antioxidant capacity and in turn influence the timing and success of migration.

Understanding the ecological and evolutionary function of stopover in migrating birds.

Global movement patterns of migratory birds illustrate their fascinating physical and physiological abilities to cross continents and oceans. During their voyages, most birds land multiple times to make so-called 'stopovers'. Our current knowledge on the functions of stopover is mainly based on the proximate study of departure decisions. However, such studies are insufficient to gauge fully the ecological and evolutionary functions of stopover. If we study how a focal trait, e.g. changes in energy stores, affects the decision to depart from a stopover without considering the trait(s) that actually caused the bird to land, e.g. unfavourable environmental conditions for flight, we misinterpret the function of the stopover. It is thus important to realise and acknowledge that stopovers have many different functions, and that not every migrant has the same (set of) reasons to stop-over. Additionally, we may obtain contradictory results because the significance of different traits to a migrant is context dependent. For instance, late spring migrants may be more prone to risk-taking and depart from a stopover with lower energy stores than early spring migrants. Thus, we neglect that departure decisions are subject to selection to minimise immediate (mortality risk) and/or delayed (low future reproductive output) fitness costs. To alleviate these issues, we first define stopover as an interruption of migratory endurance flight to minimise immediate and/or delayed fitness costs. Second, we review all probable functions of stopover, which include accumulating energy, various forms of physiological recovery and avoiding adverse environmental conditions for flight, and list potential other functions that are less well studied, such as minimising predation, recovery from physical exhaustion and spatiotemporal adjustments to migration. Third, derived from these aspects, we argue for a paradigm shift in stopover ecology research. This includes focusing on why an individual interrupts its migratory flight, which is more likely to identify the individual-specific function(s) of the stopover correctly than departure-decision studies. Moreover, we highlight that the selective forces acting on stopover decisions are context dependent and are expected to differ between, e.g. K-/r-selected species, the sexes and migration strategies. For example, all else being equal, r-selected species (low survival rate, high reproductive rate) should have a stronger urge to continue the migratory endurance flight or resume migration from a stopover because the potential increase in immediate fitness costs suffered from a flight is offset by the expected higher reproductive success in the subsequent breeding season. Finally, we propose to focus less on proximate mechanisms controlling landing and departure decisions, and more on ultimate mechanisms to identify the selective forces shaping stopover decisions. Our ideas are not limited to birds but can be applied to any migratory species. Our revised definition of stopover and the proposed paradigm shift has the potential to stimulate a fruitful discussion towards a better evolutionary ecological understanding of the functions of stopover. Furthermore, identifying the functions of stopover will support targeted measures to conserve and restore the functionality of stopover sites threatened by anthropogenic environmental changes. This is especially important for long-distance migrants, which currently are in alarming decline.

Does hatch date set the clock? Timing of post‐fledging movements for families of a colonially breeding, long‐distance migratory songbird

Factors that influence the development of migration timing in juvenile songbirds have implications for the ability of individuals to respond positively to rapid environmental changes. We investigated the impacts of nest timing on the post‐breeding movement timing of juveniles and adults of a migratory songbird. We tested whether first egg date and environmental factors predicted the initiation of post‐breeding stages: fledge date for juveniles, and colony departure date for both adults and juveniles. At breeding colonies of purple martin Progne subis in southern Ontario, Canada, we monitored nests to determine the date of nest initiation (‘first egg date') and deployed 122 coded radio‐frequency tracking tags on young and adults to determine the timing of post‐breeding stages. We found that first egg date, the number of nestmates, and age of parents were the main predictors of fledge date. Of these three factors, only first egg date carried through post‐breeding to influence colony departure date for juvenile birds, but this relationship weakened between first egg date and departure date. Nestmates tended to fledge together (range 0–4 days) but exhibited greater variation in colony departure timing (range 0–11 days). Further, while first egg influenced departure date, increasing variation between fledging and departure led to some birds departing breeding colonies at a younger age, suggesting influence of local environmental factors (e.g. social or photoperiod change) in departure decisions. The timing of adult colony departure date was independent of first egg dates. In sum, our results suggest a role for first egg dates in setting timing of post‐breeding movements, but with variation introduced between fledge and departure dates. Experimental manipulations of photoperiod in a wild setting are needed and future research should investigate whether the timing of movement driven by nesting timing, holds across the rest of migration or even the lifetime of bird.