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Although age-related spatial segregation is ubiquitous, the underlying mechanisms are poorly understood. Here, we aim to elucidatethe processes behind a previously established age-related foraging distribution of red knots (Calidris canutus canutus) in their mainwintering area in West Africa (Banc d’Arguin, Mauritania). Based on 10 years of observations of 1232 uniquely color-ringed individualsof 1 to 18+ years old, we examined whether the observed age-related foraging distribution resulted from 1) spatial differences in mortalityor 2) age-related shifts in habitat use. Using multistate capture–recapture modeling, we showed that with age foraging red knotsmoved away from the shoreline, that is, to areas with fewer surprise attacks by raptors. Considering uncertainties in the subjectivegradient in predation danger with increasing distance from shore (as assessed from correlations between vigilance and distance fromshore in foraging birds), we applied 2 different danger zone boundaries, at 40 m and 500 m from shore. Between years, red knots hada much higher chance to move from the dangerous nearshore area to the “safe” area beyond (71–78% and 26% for 40-m and 500-mdanger zone boundary, respectively), than vice versa (4% and 14%). For neither danger zone boundary value did we find differencesin annual mortality for individuals using either dangerous or safe zone, so the move away from the shore with age is attributed to individualcareers rather than differential mortality. We argue that longitudinal studies like ours will reveal that ontogenetic shifts in habitatuse are more common than so far acknowledged.

Migratory bird populations may be limited during one or more seasons, and thus at one or more places, but there is a dearth of empirical examples of this possibility. We analyse seasonal survival in a migratory shellfish-eating shorebird (red knot Calidris canutus islandica) during a series of years of intense food limitation on the nonbreeding grounds (due to overfishing of shellfish stocks), followed by a relaxation period when destructive harvesting had stopped and food stocks for red knots recovered. For the estimation of seasonal survival from the 15 yr-long near-continuous capture–resight dataset, we introduce a ‘rolling window’ approach for data exploration, followed by selection of the best season definition. The average annual apparent survival over all the years was 0.81 yr-1. During the limitation period, survival probability of adult red knots was low in winter (0.78 yr-1), but this was compensated by high survival in summer (0.91 yr-1). During the relaxation period survival rate levelled out with a winter value of 0.81 yr-1 and a summer survival of 0.82 yr-1. The fact that during the cockle-dredging period the dip in survival in winter was completely compensated by higher survival later in the annual cycle suggests sequential density dependence. We conclude that seasonal compensation in local survival (in concert with movements to areas apparently below carrying capacity) allowed the islandica population as a whole to cope, in 1998–2003, with the loss of half of the suitable feeding habitat in part of the nonbreeding range, the western Dutch Wadden Sea. As a more general point, we see no reason why inter-seasonal density dependence should not be ubiquitous in wildlife populations, though its limits and magnitude will depend on the specific ecological contexts. We elaborate the possibility that with time, and in stable environments, seasonal mortality evolves so that differences in mortality rates between seasons would become erased.

Sexual size dimorphism (SSD) implies correlated differences in energetic requirements and feeding opportunities, such that sexes will face different trade-offs in habitat selection. In seasonal migrants, this could result in a differential spatial distribution across the wintering range. To identify the ecological causes of sexual spatial segregation, we studied a sexually dimorphic shorebird, the bar-tailed godwit Limosa lapponica, in which females have a larger body and a longer bill than males. With respect to the trade-offs that these migratory shorebirds experience in their choice of wintering area, northern and colder wintering sites have the benefit of being closer to the Arctic breeding grounds. According to Bergmann's rule, the larger females should incur lower energetic costs per unit of body mass over males, helping them to winter in the cold. However, as the sexes have rather different bill lengths, differences in sex-specific wintering sites could also be due to the vertical distribution of their buried prey, that is, resource partitioning. Here, in a comparison between six main intertidal wintering areas across the entire winter range of the lapponica subspecies in northwest Europe, we show that the percentage of females between sites was not correlated with the cost of wintering, but was positively correlated with the biomass in the bottom layer and negatively with the biomass in the top layer. We conclude that resource partitioning, rather than relative expenditure advantages, best explains the differential spatial distribution of male and female bar-tailed godwits across northwest Europe.

The evolutionary function and maintenance of variation in animal personality is still under debate. Variation in the size of metabolic organs has recently been suggested to cause and maintain variation in personality. Here, we examine two main underlying notions: (i) that organ sizes vary consistently between individuals and cause consistent behavioural patterns, and (ii) that a more exploratory personality is associated with reduced survival. Exploratory behaviour of captive red knots (Calidris canutus, a migrant shorebird) was negatively rather than positively correlated with digestive organ (gizzard) mass, as well as with body mass. In an experiment, we reciprocally reduced and increased individual gizzard masses and found that exploration scores were unaffected. Whether or not these birds were resighted locally over the 19 months after release was negatively correlated with their exploration scores. Moreover, a long-term mark-recapture effort on free-living red knots with known gizzard masses at capture confirmed that local resighting probability (an inverse measure of exploratory behaviour) was correlated with gizzard mass without detrimental effects on survival. We conclude that personality drives physiological adjustments, rather than the other way around, and suggest that physiological adjustments mitigate the survival costs of exploratory behaviour. Our results show that we need to reconsider hypotheses explaining personality variation based on organ sizes and differential survival.

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Estimates of seasonal mortality for long-distance migrant birds are extremely challenging to collect and consequently reports are scarce. Determining when and where mortality occurs within the annual cycle is important for an understanding of population dynamics and the evolutionary drivers of long-distance migration. We collected data on seasonal survival in a mark-recapture study of colour-marked Red Knots Calidris canutus canutus in their main wintering area at tropical Banc d'Arguin, Mauritania, West Africa. Our study population breeds 9,000 km to the northeast on Taymyr Peninsula, central northern Siberia. Our results show that annual apparent survival decreased from 0.87 +/- A 0.01 (SE) in 2002-2005 to 0.78 +/- A 0.02 in 2006-2009. During the 3-year time-window between 2006 and 2009, additional resightings just before migration and after return to the wintering grounds allowed us to partition the year into two periods: the non-breeding period on the Banc d'Arguin, and the migration and breeding period away from it. We estimated that, on the Banc d'Arguin, the 2-month apparent survival rate was 0.94 +/- A 0.01, whereas 2-month survival approached unity during the rest of year. Hence, most mortality occurred on the tropical wintering grounds. We review the possible physiological and ecological stressors involved and discuss the generality of these results.

The distribution of Dark-bellied Brent Geese Branta b. bernicla moulting on the Taimyr Peninsula, in the Russian arctic, varies between years depending on whether the birds had a successful breeding season. Counts made of moulting flocks show that major shifts in numbers occur, particularly in non-breeding years, when in line with Salomonsen’s (1968) hypothesis a higher proportion of the population moults further north. For instance, the delta of the Lower Taimyr River in the northern part of the Taimyr Peninsula held 10-times more moulting Dark-bellied Brent Geese in 1989, a non-breeding year, than it did in the good 1990 breeding season. At a more local scale, in good breeding years family groups with small goslings tend to move away from breeding islands in the Pyasina Delta, western Taimyr, to avoid gosling predation by Taimyr Gulls Larus taimyrensis which nest in colonies on the same islands, whereas in poor breeding years adult geese concentrate on these same islands to moult and avoid the mainland sites used for moulting in good breeding years. Failed breeders have greater freedom than parent birds to choose where to moult as successful breeders remain with their goslings to protect and guide them to the safest nursery and moult areas. Re-captures of ringed Darkbellied Brent Geese at a moulting site in the Pyasina Delta found that, in poor breeding years, up to one-fifth the birds had moulted at the site previously, but that the majority of ringed birds known to be still alive were not site-faithful to their moulting grounds.

Two populations of Bar-tailed Godwits Limosa lapponica occur along the East-Atlantic Flyway. The European population (L. I. lapponica) is supposed to breed in northern Scandinavia and has been suggested to only winter in Europe. The Afro-Siberian population (taymyrensis) is supposed to breed in Northern Siberia and is thought to winter exclusively in West Africa. An analysis of 946 metal ring recoveries accumulated by EURING (with data going back to 1935), in combination with an analysis of over 13,000 resightings of almost 4000 individuals marked with colour-rings in 2001-2010, enabled us to examine whether there is evidence for overlap of the populations in summer and winter. Nearly all marked individuals behaved according to the previously suggested leap-frog migration pattern. On the basis of the present sample, only 0.8% of (colour) ringed birds that were recovered and/or resighted on the wintering grounds in Europe or West-Africa made a change between the two supposed wintering areas. This is far less than was previously estimated on the basis of biometric data. The distinct migratory behaviour of the two populations makes them near-completely separated in summer and winter. The Bar-tailed Godwit along the East-Atlantic Flyway thus exhibits a clear leap-frog migration, in which the Siberian breeders winter south of the European breeders.

Achtergrond en doel: Seksueel misbruik komt relatief vaak voor bij jongeren met een licht verstandelijke beperking. Het lijkt erop dat (vermoedens van) seksueel misbruik onder deze jongeren minder vaak gemeld wordt dan het plaatsvindt. Er is onderzocht hoe vaak begeleiders seksueel misbruik bij hun cliënten vermoeden, hoe vaak ze dit formeel melden bij het meldpunt van de instelling, en welke factoren mogelijk samenhangen met het meldgedrag van groepsleiders. Methode: 49 van de 118 benaderde groepsleiders van een orthopedagogisch behandelcentrum in het midden van Nederland hebben meegedaan aan het onderzoek, Dit waren 17 mannen en 32 vrouwen met een gemiddelde leeftijd van 33.7 jaar (SD = 9.4). Zij hebben een vragenlijst ingevuld over het meemaken van (vermoedens van) seksueel misbruik tijdens hun dienst, hun meldgedrag en de mate van kennis over het beleid van de instelling over seksueel misbruik. Ook de redenen van het wel of niet formeel melden van het (vermoedelijke) seksueel misbruik en de demografische gegevens van respondenten werden gevraagd, om te onderzoeken of er factoren zijn die samenhangen met het wel of niet melden van (vermoedens van) seksueel misbruik. Resultaten: Door het lage aantal respondenten dat aangaf (een vermoeden van) seksueel misbruik te hebben meegemaakt tijdens zijn dienst (n=13), konden er geen uitspraken gedaan worden over het meldgedrag van de groepsleiding. Er is daarom onderzocht of het kennisniveau van de respondenten over het beleid van de instelling (de nota, het protocol, de meldplicht en het meldpunt) significant samenhangt met de persoonskenmerken (geslacht, leeftijd, opleiding) van groepsleiding. Dit bleek niet het geval te zijn. Ruim de helft van de respondenten kent de inhoud van de nota en het protocol slechts gedeeltelijk. Conclusie: Meer onderzoek naar het meldgedrag van groepsleiding over (vermoedens van) seksueel misbruik is nodig om uitspraken te kunnen doen over meldgedrag en mogelijk samenhangende factoren. De inst

Capsule Population estimates based on the mark-resighting method can be a useful alternative to population-wide counts. Aims To investigate whether the mark-resighting method can be used as an alternative to counts to estimate the size of wader populations. Methods Individual colour-marking and subsequent resightings allowed accurate estimates of annual survival for three populations of waders, on which basis we could estimate the actual number of marked birds alive. Densities of marked birds were determined on sites away (2000-4300 km) from the ringing locations expecting marked birds to be randomly distributed among non-marked conspecifics. Population sizes are estimated by combining these densities with the number of marked birds alive. Results We found indications that the distribution of marked birds was indeed random in the locations away from the site of marking. The estimated population size of Red Knot Calidris canutus canutus was in accordance with the most recent estimates based on counts. Our estimate of the Calidris c. islandica population was somewhat lower, and that of the Bar-tailed Godwit Limosa lapponica taymyrensis population was considerably lower than the latest estimates based on counts. Conclusion Population estimates based on the mark-resighting method can be a useful alternative for, or addition to, population-wide counts, as long as the assumption of random distribution of marked birds at the reading sites is taken into account. We conclude that the Afro-Siberian Bar-tailed Godwit population has recently decreased in size or has been substantially overestimated during the counts.

Vanuit wetenschappelijk oogpunt is het interessant te weten hoe groot het leefgebied is van individuele dieren en waarom soorten daarin verschillen. Vanuit het oogpunt van natuurbeschgerming is dit mogelijk nog belangrijker. Het is essentieel om te weten hoe groot een beschermd gebied moet zijn voor een bepaalde soort om hier langere tijd in te kunnen verblijven. Van Kanoeten was al bekend dat ze in ons Waddengebied flink rondzwerven. Door Kanoeten op grote schaal individueel te merken met kleurringen en ze jarenlang te volgen, werd het mogelijk veel meer over het gebruik en de grootte van hun leefgebied te weten te komen. Door daarnaast ook een aantal vogels te voorzien van zendertjes konden de verplaatsingen van individuen binnen een korte periode in kaart worden gebracht. Een bijdrage vanuit NIOZ

Assuming that animals respond optimally to environmental changes, both behavior and physiology should be useful indicators of the way that animals perceive the quality of their environment. For verification, we examined foraging time and gizzard size of the red knot (Calidris canutus), a long-distance migrant shorebird that ingests hard-shelled mollusk prey whole and therefore readily faces digestive constraints. Nevertheless, even when digestively bottlenecked, knots can still enhance their daily energy intake by flexibly increasing the size of their digestive system, notably the gizzard, and/or by feeding longer per day. Whether such adjustments are actually necessary depends on the quality (condition) of their food, i.e., the ratio of flesh to shell mass. Hence, gizzard mass and daily foraging time in knots may be reliable indicators of the quality of their invertebrate prey. This idea is explored by using field data on radio-marked knots during late summer in the Dutch Wadden Sea. Their gizzards were measured using ultrasonography and the knots' movements and working hours were monitored using handheld receivers and automated radio-tracking systems. Indeed, gizzard mass alone predicted annual variation in food quality satisfactorily; however, adding estimates for daily foraging time significantly improved the predictions. We discuss and conceptualize how knots may trade off digestive organ size against foraging time upon arrival in the Wadden Sea, given the quality and quantity of the food on offer, and why these findings are relevant in the context of conservation of migration systems., Assuming that animals respond optimally to environmental changes, both behavior and physiology should be useful indicators of the way that animals perceive the quality of their environment. For verification, we examined foraging time and gizzard size of the red knot (Calidris canutus), a long-distance migrant shorebird that ingests hard-shelled mollusk prey whole and therefore readily faces digestive constraints. Nevertheless, even when digestively bottlenecked, knots can still enhance their daily energy intake by flexibly increasing the size of their digestive system, notably the gizzard, and/or by feeding longer per day. Whether such adjustments are actually necessary depends on the quality (condition) of their food, i.e., the ratio of flesh to shell mass. Hence, gizzard mass and daily foraging time in knots may be reliable indicators of the quality of their invertebrate prey. This idea is explored by using field data on radio-marked knots during late summer in the Dutch Wadden Sea. Their gizzards were measured using ultrasonography and the knots' movements and working hours were monitored using handheld receivers and automated radio-tracking systems. Indeed, gizzard mass alone predicted annual variation in food quality satisfactorily; however, adding estimates for daily foraging time significantly improved the predictions. We discuss and conceptualize how knots may trade off digestive organ size against foraging time upon arrival in the Wadden Sea, given the quality and quantity of the food on offer, and why these findings are relevant in the context of conservation of migration systems.

The probability of successful breeding by Brent geese in the Arctic appears to be positively correlated with the mass of females when they depart from spring staging areas in North-western Europe. To clarify the mechanism behind this relationship we investigated the significance of flown-in female body stores for breeding over six summer seasons (1990-1995) in the Pyasina Delta in Taimyr, Russia. Female Brent Geese were caught upon arrival on the breeding grounds. Changes in female body mass and the timing and duration of nest recesses were recorded via electronic weighing platforms placed under their nests. Average female body masses declined through the breeding season; from 1464 g at arrival to 1269 g after egg laying and 1066 g at hatching, which was supposed to be close to lean body mass. Thus half of the stores were used between arrival and clutch completion, the other half during incubation. All females foraged during incubation. On average they left the nest 13.1 times every 24 hours, resulting in a daily recess time of 198 min during the first 21 days of incubation. Females were less likely to leave the nest during the last three days of incubation. Leaving the nest was risky: 40% of the Brent Goose nests in the study area lost one or more eggs to gulls during absence of the female. We estimated that 52% of the energy required during incubation was derived from body stores and the rest (48%) from food intake.

Besides the "normal" challenge of obtaining adequate intake rates in a patchy and dangerous world, shorebirds foraging in intertidal habitats face additional environmental hurdles. The tide forces them to commute between a roosting site and feeding grounds, twice a day. Moreover, because intertidal food patches are not all available at the same time, shorebirds should follow itineraries along the best patches available at a given time. Finally, shorebirds need additional energy stores in order to survive unpredictable periods of bad weather, during which food patches are covered by extreme tides, In order to model such tide-specific decisions, we applied stochastic dynamic programming in a spatially explicit context. Two assumptions were varied, leading to four models. First, birds had either perfect (ideal) or no (non-ideal) information about the intake rate at each site. Second, traveling between sites was either for free or incurred time and energy costs (non-free). Predictions were generated for three aspects of foraging: area use, foraging routines, and energy stores. In general, non-ideal foragers should feed most intensely and should maintain low energy stores. If traveling for such birds is free, they should feed at a random site; otherwise, they should feed close to their roost. Ideal foragers should concentrate their feeding around low tide (especially when free) and should maintain larger energy stores (especially when non-free). If traveling for such birds is free, they should feed at the site offering the highest intake rate; otherwise, they should trade off travel costs and intake rate. Models were parameterized, for Red Knots (Calidris canutus) living in the Dutch Wadden Sea in late summer, an area for which detailed, spatially explicit data on prey densities and tidal heights are available. Observations of radio-marked knots (area use) and unmarked knots (foraging routines, energy stores) showed the closest match with the ideal/non-free model. We

There is a widespread concern about the direct and indirect effects of industrial fisheries; this concern is particularly pertinent for so-called “marine protected areas” (MPAs), which should be safeguarded by national and international law. The intertidal flats of the Dutch Wadden Sea are a State Nature Monument and are protected under the Ramsar convention and the European Union's Habitat and Birds Directives. Until 2004, the Dutch government granted permission for ~75% of the intertidal flats to be exploited by mechanical dredgers for edible cockles (Cerastoderma edule). Here we show that dredged areas belonged to the limited area of intertidal flats that were of sufficient quality for red knots (Calidris canutus islandica), a long-distance migrant molluscivore specialist, to feed. Dredging led to relatively lower settlement rates of cockles and also reduced their quality (ratio of flesh to shell). From 1998 to 2002, red knots increased gizzard mass to compensate for a gradual loss in shellfish quality, but this compensation was not sufficient and led to decreases in local survival. Therefore, the gradual destruction of the necessary intertidal resources explains both the loss of red knots from the Dutch Wadden Sea and the decline of the European wintering population. This study shows that MPAs that do not provide adequate protection from fishing may fail in their conservation objectives., There is a widespread concern about the direct and indirect effects of industrial fisheries; this concern is particularly pertinent for so-called “marine protected areas” (MPAs), which should be safeguarded by national and international law. The intertidal flats of the Dutch Wadden Sea are a State Nature Monument and are protected under the Ramsar convention and the European Union's Habitat and Birds Directives. Until 2004, the Dutch government granted permission for ~75% of the intertidal flats to be exploited by mechanical dredgers for edible cockles (Cerastoderma edule). Here we show that dredged areas belonged to the limited area of intertidal flats that were of sufficient quality for red knots (Calidris canutus islandica), a long-distance migrant molluscivore specialist, to feed. Dredging led to relatively lower settlement rates of cockles and also reduced their quality (ratio of flesh to shell). From 1998 to 2002, red knots increased gizzard mass to compensate for a gradual loss in shellfish quality, but this compensation was not sufficient and led to decreases in local survival. Therefore, the gradual destruction of the necessary intertidal resources explains both the loss of red knots from the Dutch Wadden Sea and the decline of the European wintering population. This study shows that MPAs that do not provide adequate protection from fishing may fail in their conservation objectives.

Besides the “normal” challenge of obtaining adequate intake rates in a patchy and dangerous world, shorebirds foraging in intertidal habitats face additional environmental hurdles. The tide forces them to commute between a roosting site and feeding grounds, twice a day. Moreover, because intertidal food patches are not all available at the same time, shorebirds should follow itineraries along the best patches available at a given time. Finally, shorebirds need additional energy stores in order to survive unpredictable periods of bad weather, during which food patches are covered by extreme tides. In order to model such tide-specific decisions, we applied stochastic dynamic programming in a spatially explicit context. Two assumptions were varied, leading to four models. First, birds had either perfect (ideal) or no (non-ideal) information about the intake rate at each site. Second, traveling between sites was either for free or incurred time and energy costs (non-free). Predictions were generated for three aspects of foraging: area use, foraging routines, and energy stores. In general, non-ideal foragers should feed most intensely and should maintain low energy stores. If traveling for such birds is free, they should feed at a random site; otherwise, they should feed close to their roost. Ideal foragers should concentrate their feeding around low tide (especially when free) and should maintain larger energy stores (especially when non-free). If traveling for such birds is free, they should feed at the site offering the highest intake rate; otherwise, they should trade off travel costs and intake rate. Models were parameterized for Red Knots (Calidris canutus) living in the Dutch Wadden Sea in late summer, an area for which detailed, spatially explicit data on prey densities and tidal heights are available. Observations of radio-marked knots (area use) and unmarked knots (foraging routines, energy stores) showed the closest match with the ideal/non-free model. We conc, Besides the “normal” challenge of obtaining adequate intake rates in a patchy and dangerous world, shorebirds foraging in intertidal habitats face additional environmental hurdles. The tide forces them to commute between a roosting site and feeding grounds, twice a day. Moreover, because intertidal food patches are not all available at the same time, shorebirds should follow itineraries along the best patches available at a given time. Finally, shorebirds need additional energy stores in order to survive unpredictable periods of bad weather, during which food patches are covered by extreme tides. In order to model such tide-specific decisions, we applied stochastic dynamic programming in a spatially explicit context. Two assumptions were varied, leading to four models. First, birds had either perfect (ideal) or no (non-ideal) information about the intake rate at each site. Second, traveling between sites was either for free or incurred time and energy costs (non-free). Predictions were generated for three aspects of foraging: area use, foraging routines, and energy stores. In general, non-ideal foragers should feed most intensely and should maintain low energy stores. If traveling for such birds is free, they should feed at a random site; otherwise, they should feed close to their roost. Ideal foragers should concentrate their feeding around low tide (especially when free) and should maintain larger energy stores (especially when non-free). If traveling for such birds is free, they should feed at the site offering the highest intake rate; otherwise, they should trade off travel costs and intake rate. Models were parameterized for Red Knots (Calidris canutus) living in the Dutch Wadden Sea in late summer, an area for which detailed, spatially explicit data on prey densities and tidal heights are available. Observations of radio-marked knots (area use) and unmarked knots (foraging routines, energy stores) showed the closest match with the ideal/non-free model. We conc

Om de rol van de Waddenzee en de achtergronden van de wadvogeltrek beter te begrijpen doen Nederlandse vogelonderzoekers in het kader van de WIWO (Stichting Werkgroep Internationaal Wad- en Watervogelonderzoek) al vele jaren onderzoek aan wadvogels en waddengebieden elders in de wereld. In eerste instantie werden vergelijkingen gemaakt tussen hele wadvogelgemeenschappen en tussen de hoeveelheden bodemdieren beschikbaar als wadvogelvoedsel; later kwamen ook soortspecifieke ecologische eigenschappen als opvetsnelheid en energieverbruik in beeld. In dit artikel een voortgangsreportage van dit type onderzoek met o.a. een vergelijking van de voor- en nadelen van overwinteren in een West-Afrikaans waddengebied t.o.v. de Waddenzee of andere gebieden in Noordwest-Europa, en de ecologische aspecten van de trek van diverse populaties van de kanoetstrandloper Calidris canutus (gekozen als modelsoort voor wadvogels die aan lange-afstandstrek doen)

Door middel van zendertjes en automatische ontvangststations in de westelijke Waddenzee werden de bewegingspatronen tussen de foerageerbebieden en de hoogwaterverblijfplaatsen van de kanoet-populatie in beeld gebracht, en konden verbanden worden gelegd met het voedselaanbod op verschillende locaties. Verslag van lopend onderzoek

Tijdens deze studie is onderzocht welke geheimen adolescenten hebben en wat dat tot gevolgen heeft. Aan dit onderzoek hebben 152 adolescenten deelgenomen. Er is gekeken naar het verband tussen geheimen en delinquentie, depressie, relatiekwaliteit en positieve gevoelens. Daarnaast is gekeken welke rol de afwezigheid van vertrouwenspersonen speelt. Uit het onderzoek kwam naar voren dat jongeren die geheimen hebben een slechtere relatiekwaliteit met ouders hebben en meer delinquentie en depressie vertoonden. Als ze vertrouwenspersonen hadden, bleken deze effecten weg te vallen. Het hebben van geheimen over geld en over ouders en/of familie zijn een voorspeller voor depressieve gevoelens. Daarnaast bleek dat het hebben van geheimen over drugs, roken of alcoholgebruik vooral leidden tot delinquentie. Tevens bleek er alleen een sekseverschil te bestaan voor delinquentie.

Tijdens deze studie is onderzocht welke geheimen adolescenten hebben en wat dat tot gevolgen heeft. Aan dit onderzoek hebben 152 adolescenten deelgenomen. Er is gekeken naar het verband tussen geheimen en delinquentie, depressie, relatiekwaliteit en positieve gevoelens. Daarnaast is gekeken welke rol de afwezigheid van vertrouwenspersonen speelt. Uit het onderzoek kwam naar voren dat jongeren die geheimen hebben een slechtere relatiekwaliteit met ouders hebben en meer delinquentie en depressie vertoonden. Als ze vertrouwenspersonen hadden, bleken deze effecten weg te vallen. Het hebben van geheimen over geld en over ouders en/of familie zijn een voorspeller voor depressieve gevoelens. Daarnaast bleek dat het hebben van geheimen over drugs, roken of alcoholgebruik vooral leidden tot delinquentie. Tevens bleek er alleen een sekseverschil te bestaan voor delinquentie.