Nesting Behavior Research Articles

Effects of salinity on nest-building behaviour in a marine fish.

BackgroundParental allocation and reproductive success are often strongly influenced by environmental factors. In this respect, salinity is a key factor influencing species distributions and community structure in aquatic animals. Nevertheless, the effects of salinity on reproductive behaviours are not well known. Here, we used the sand goby (Pomatoschistus minutus), a small fish inhabiting a range of different salinities, to experimentally assess the effects of changes in salinity on nesting behaviour, a key component of reproduction in sand gobies and many other taxa.ResultsWe found that salinity levels influenced some aspects of male nesting behaviour (i.e. nest entrance size) but not others (i.e. latency to build a nest, choice of nest site, sand on top of nest) and that small and large individuals were differently affected. In particular, the importance of body size in adjustment of nest entrance depended on the salinity level.ConclusionThe results support the prediction that geographically widespread aquatic species, such as sand gobies, are able to perform well under a range of salinity levels. The phenotype by environment interaction found between male size and behavioural responses to salinity can, in turn, help to explain the notable variation observed in nest-building (and other) behaviours closely linked to reproduction.Electronic supplementary materialThe online version of this article (doi:10.1186/s12898-016-0067-y) contains supplementary material, which is available to authorized users.

Chimpanzee research and conservation in Bossou and the Nimba Mountains: a long-term international collaborative effort in West Africa.

The Nimba Mountains are a West African Natural World Heritage site located in the range of the Guineo-equatorial evergreen rainforest, renowned for its rich biodiversity with a high level of endemism. In 1976, Yukimaru Sugiyama from Kyoto University initiated the long-term study of chimpanzees at Bossou, a Guinean village situated 5km from the northern foothills of Nimba. This Japanese initiative has provided key discoveries and insights on our closest living evolutionary relatives over the 40 past years, and has grown to become an international collaboration with a research focus extended to adjacent chimpanzee communities. The present paper describes a mid-term behavioral and ecological study on wild chimpanzees populating the southern slope of the Nimba Mountains, conducted in the framework of this collaborative project. It aimed to assess the status and ecological requirements of chimpanzees in order to formulate purpose-built actions for their conservation. We estimated a density of 0.46 chimpanzee per km(2) using nest count methods from line transects. We used logistic and Poisson regressions to investigate basic ecological characteristics of chimpanzees in relation to habitat composition and structure, topography and seasonality. We performed an in-depth analysis of their nesting and feeding behaviors, and identified important components of their diet; we also recorded their year-round ranging patterns. Our findings highlight the importance of old secondary forest and high-altitude habitats for these chimpanzees. We discuss the results in the light of other studies from the perspective of the conservation of the species and its natural habitat.

Características de la Anidación de Lepidochelys olivacea (Testudinata: Cheloniidae) entre el 2010 y 2012 en Playa Tortuga Ojochal de Osa, Puntarenas, Costa Rica

En las playas de arribada de Costa Rica el comportamiento de anidación y otros aspectos de la biología de Lepidochelys olivacea han sido ampliamente estudiados, pero existe poca información acerca de las playas de anidación solitaria en especial del Pacífico Sur. Por este motivo el objetivo del presente estudio es describir los aspectos relevantes del comportamiento de la anidación de L. olivacea en Playa Tortuga, Pacífico Sur de Costa Rica, durante tres temporadas de anidación (2010, 2011, 2012). Se dividió la playa en 14 sectores de 100m cada uno, a partir de esto se realizaron patrullajes todas noches durante los meses de julio a diciembre (2010) y de julio a enero (2011, 2012), con el fin de registrar el comportamiento de anidación de las tortugas y proteger sus nidadas. Las hembras observadas fueron identificadas mediante la aplicación de marcas metálicas en sus aletas posteriores, se registró el número de huevos, el sector de ubicación de las nidadas, la hora, datos biométricos ancho y largo curvo del caparazón (ACC-LCC), también se contabilizaron todas las nidadas efectivas (con o sin tortuga). Se logró marcar 100 hembras de L. olivacea, y se contabilizaron un total de 233 nidadas en Playa Tortuga. Se determinó una frecuencia de anidación de dos veces por temporada con un intervalo de reanidación de 14 a 20 días y para cuatro individuos se registró un período de remigración de un año. Se estimó para las tres temporadas una población total de 117 hembras y se determinó el período de agosto a setiembre como el pico de anidación. Con respecto a la biometría, se obtuvo un valor de LCC promedio de 69.91±1.05cm y un valor de ACC promedio de 70.476+/-1.767cm. Un total de 18 711 huevos fueron colectados y 9 858 neonatos fueron reclutados. Se ha comprobado a partir de las tres temporadas de monitoreo que Playa Tortuga debe de ser considerada como una playa de anidación de L. olivacea, a pesar de que que su población actual de hembras anidantes es reducida en comparación a otras playas del Pacífico Sur. El marcaje es una herramienta útil para la caracterización de la frecuencia e intervalo de reanidación.

Peregrine falcon egg pollutants

ABSTRACTThe role of the peregrine falcon (Falco peregrinus) as a bioindicator for the accumulation of organohalogen compounds and other persistent organic pollutants has been established in field studies. Biometric indices for damage caused by pollutants such as the shell thickness and the shell index were determined and the egg contents were analyzed for various pollutants by gas chromatography/mass spectrometry. A wide range of chemically activated luciferase expression (CALUX®) bioassays were performed on subsamples of the eggs.The following organohalogen compounds were found in the eggs of 2009: dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethane, heptachlor epoxide, hexachlorobenzene, dieldrin, hexachlorocyclohexane, polychlorobiphenyls and polychlorodibenzodioxins and polychlorodibenzofurans, polybromodiphenyl ethers, hexabromocyclododecane, tetrabromobisphenyl A, perfluoro compounds, and mercury. The DDT metabolite, dichlorodiphenyldichloroethene (DDE) (11,800 ng/g dry matter), was found to be the most highly concentrated egg contaminant followed by 2,2′,4,4′,5,5′-hexachlorobiphenyl (3800 ng/g). After a past general drop in pollution level, most egg contaminants presently plateau at levels that may still exceed limit values in foods of animal origin (DDE) or even toxicological thresholds (polychlorobiphenyls + polychlorodibenzodioxins, polybromodiphenyl ethers, perfluorooctanesulfonate, methylmercury).Accumulation of DDE could be shown in peregrine falcon eggs from the uplands of Southwest Germany with elevations up to 1500 m, presumably due to its global distribution and its cold condensation in higher altitudes. In contrast, the concentration of polychlorobiphenyls in falcon eggs decreases with elevation, indicating that these pollutants originate mainly from conurbations and local industrial sites.Significant negative correlations were found between both shell index and thickness and the concentration of Hg. A deleterious effect is also evident from a no-observed-adverse-effect level of 120 ng MeHg per gram egg determined by other authors in chronic feeding studies with ibises, which resulted in decreased egg productivity and male homosexual nesting and courtship behavior. The average Hg concentration in the peregrine falcon eggs from 2009 is almost four times higher than this level. MeHg accounted for 82.5% of the Hg present in the eggs of 2009 and 2010.The cell test DR CALUX® for screening of dioxin-like activities can be used to detect not only the 29 regulated dioxin-like substances but also many other persistent organic pollutants with dioxin-like potencies, such as mixed halogenated dioxins/biphenyls. In our case, the results of bioanalytical screening methods showed no additional effect of other compounds with dioxin-like activity.Ninety-three out of 177 analytes sought could be detected in the eggs. Chlorinated paraffins, organotin compounds, some pesticides that are still in use, and phthalic esters with the exception of traces of diethylhexyl phthalate could be excluded. All pollutants found in the eggs belong to substance classes banned by the Stockholm and Minamata Conventions.

Nesting ecology of hawksbill turtles at a rookery of international significance in Australia’s Northern Territory

Context Following centuries of intense human exploitation, the global stocks of hawksbill turtle have decreased precipitously and the species is currently considered Critically Endangered by the IUCN. Australia supports the largest breeding aggregations worldwide; however, there are no accurate estimates of population abundance and seasonality for hawksbill turtles at important nesting grounds in eastern Arnhem Land. Aims This study was designed to fill in this lack of ecological information and assist with the conservation and management of hawksbill turtles. More specifically, our overarching goals were to assess nesting seasonality, habitat preferences and provide the first estimate of annual nesting population size at a Northern Territory rookery. Methods In 2009 and 2010 we collected beach monitoring, satellite telemetry and sand temperature data over two nesting seasons at a group of three islands located 30 km off Groote Eylandt in the Gulf of Carpentaria, northern Australia. We subsequently analysed these data to unravel hawksbill nesting behaviour and reproductive outputs, and examined the vulnerability of this rookery to climate change. Key results Hawksbill turtle nesting seasonality consistently started in mid-May, peaked in mid-August and ended in late November. Annual nesting abundance showed a near 3-fold increase between 2009 and 2010, with an average of 220 and 580 hawksbill females nesting on this island group respectively. Sand temperature at 50 cm reached more than 30°C at all monitored sites during most of the peak of the incubation period. Conclusions This remote and untouched group of islands constitutes a major hawksbill turtle rookery both nationally and globally. While anthropogenic impacts and predation are low year round, climate change threatens to skew hatchling sex ratios, eventually leading to an increase in hatchling mortality. Implications Additional ground-based surveys are required to refine the accuracy of population estimates presented in this study. Given the paucity of data in the region, we recommend this island group off Groote Eylandt be used as a population-monitoring index site for the eastern Arnhem Land hawksbill turtle breeding aggregation.

Application of video recording technology to improve husbandry and reproduction in the carmine bee-eater (Merops n. nubicus).

Incorporating technology with research is becoming increasingly important to enhance animal welfare in zoological settings. Video technology is used in the management of avian populations to facilitate efficient information collection on aspects of avian reproduction that are impractical or impossible to obtain through direct observation. Disney's Animal Kingdom(®) maintains a successful breeding colony of Northern carmine bee-eaters. This African species is a cavity nester, making their nesting behavior difficult to study and manage in an ex situ setting. After initial research focused on developing a suitable nesting environment, our goal was to continue developing methods to improve reproductive success and increase likelihood of chicks fledging. We installed infrared bullet cameras in five nest boxes and connected them to a digital video recording system, with data recorded continuously through the breeding season. We then scored and summarized nesting behaviors. Using remote video methods of observation provided much insight into the behavior of the birds in the colony's nest boxes. We observed aggression between birds during the egg-laying period, and therefore immediately removed all of the eggs for artificial incubation which completely eliminated egg breakage. We also used observations of adult feeding behavior to refine chick hand-rearing diet and practices. Although many video recording configurations have been summarized and evaluated in various reviews, we found success with the digital video recorder and infrared cameras described here. Applying emerging technologies to cavity nesting avian species is a necessary addition to improving management in and sustainability of zoo avian populations.

Hypertrophy and polysaccharide production in the kidney associated with sexual maturation of male small-egged Kajika, Cottus pollux SE

Although renal hypertrophy during the reproductive period has been reported previously in species of Cottus, the function of the kidney in reproduction remains unknown. In order to clarify the role of the kidney in reproduction, seasonal changes in gonad and kidney weight, serum androgen levels, kidney histology, and the protein content of urine, were examined in the small-egged Kajika, Cottus pollux SE sensu Yokoyama and Goto (2005). Compared to the non-reproductive period (August), renal hypertrophy of male fish during the reproductive period (December) was equivalent to a twofold increase in kidney-somatic index values. A marked increase in epithelial cell height in the proximal convoluted tubule (PT) was correlated with elevated serum 11-ketotestosterone levels, suggesting that total kidney weight increased from the non-reproductive to the reproductive period. Periodic acid-Schiff (PAS)-positive granules containing polysaccharides were observed in the cytoplasm of PT epithelia during the reproductive period. Urine retained in the urinary bladders of males exhibiting nesting behavior contained glycoproteins and low-molecular-weight substances containing polysaccharides during the reproductive period. We discussed the role of the kidney and kidney secretions in nesting male species of Cottus.

Sargassum accumulation may spell trouble for nesting sea turtles

Sargassum accumulation may spell trouble for nesting sea turtles

Temperature-Dependent Sex Determination under Rapid Anthropogenic Environmental Change: Evolution at a Turtle's Pace?

Organisms become adapted to their environment by evolving through natural selection, a process that generally transpires over many generations. Currently, anthropogenically driven environmental changes are occurring orders of magnitude faster than they did prior to human influence, which could potentially outpace the ability of some organisms to adapt. Here, we focus on traits associated with temperature-dependent sex determination (TSD), a classic polyphenism, in a model turtle species to address the evolutionary potential of species with TSD to respond to rapid climate change. We show, first, that sex-ratio outcomes in species with TSD are sensitive to climatic variation. We then identify the evolutionary potential, in terms of heritability, of TSD and quantify the evolutionary potential of 3 key traits involved in TSD: pivotal temperature, maternal nest-site choice, and nesting phenology. We find that these traits display different patterns of adaptive potential: pivotal temperature exhibits moderate heritable variation, whereas nest-site choice and nesting phenology, with considerable phenotypic plasticity, have only modest evolutionary potential to alter sex ratios. Therefore, the most likely response of species with TSD to anthropogenically induced climate change may be a combination of microevolution in thermal sensitivity of the sex-determining pathway and of plasticity in maternal nesting behavior.

Differential Parasitism Between Two Suitable Cowbird Hosts

Host choice by the brood parasitic Brown-headed Cowbird (Molothrus ater) is an evolved response to host suitability, resulting in patterns of differential parasitism rates among species within a community. In the ponderosa pine (Pinus ponderosa) forests of the Colorado Front Range, we recorded that Western Wood-pewee (Contopus sordidulus) is infrequently parasitized (1%, n = 259 nests) by the Brown-headed Cowbird, whereas the Plumbeous Vireo (Vireo plumbeus) is heavily parasitized (51%, n = 292). To account for differences in parasitism rates on these species we experimentally parasitized pewee nests with cowbird eggs, and we compared host aggression towards cowbird models, host nest attentiveness, nest placement, and egg-laying dates in these species. Pewees accepted cowbirds eggs and reacted more aggressively towards the cowbird model than the control model, were more attentive at their nest sites than vireos, and placed their nests higher and closer to the trunk than vireos. Egg-laying dates for vireos and cowbirds overlapped more than the egg-laying dates for pewees and cowbirds. We suggest that temporal asynchrony in host availability, coupled with differences in nest placement and behavior at the nest, help to account for the observed differences in parasitism rates between these two species.

Bionomics of Melipona mondury Smith 1863 (Hymenoptera: Apidae, Meliponini) in relation to its nesting behavior

Melipona mondury Smith 1863 is an important stingless bee species pollinator and honey/pollen producer, but threatened by fragmentation of habitats throughout its range. This article presents the identification and partial characterization of nesting substrates, bionomic including population features of M. mondury by comparing data between nest architecture of natural beehive and boxes colonies. Nineteen colonies (13 in boxes and six in beehives) were analyzed with regards to substrate nesting, nest characteristics (e.g. length and width of the combs, height and diameter of the pollen and honey jar) and bee population. The average volume and diameter of the trunks cavities used for nesting of M.mondury were18.4 L and 15.8 cm; the average number of combs was 9.26; the average diameter and height of the honey pots were 2.81 cm and 3.29 cm, and the average volume of honey stored was 15.85 mL; the average height and diameter of pollen pots was 3.21 cm and 2.93 cm, respectively, while the average mass of pollen deposited was equal to 12.56 g. The population ranged from 3537 to 10281 individuals between colonies. The results suggest that the conservation of M. mondury should involve reforestation with native species from Atlantic Forest, and the dimensions of boxes should be based on the average size of the nests in the natural environment in order to support strategies of conservation and sustainable management of this species.

Common blackbirds Turdus merula use anthropogenic structures as nesting sites in an urbanized landscape

Abstract The common blackbird Turdus merula is one of the most highly urbanized bird species. However, to date, the use of anthropogenic structures as nesting sites in the common blackbird is rarely documented, and the factors influencing its use of the anthropogenic structures as nesting sites remain unclear. In this study, we systematically quantified and determined the factors influencing the use of anthropogenic structures as nesting sites in common blackbirds in a highly urbanized city of Hangzhou, China. We searched for nests of common blackbirds during four breeding seasons from 2010 to 2013. Among the 60 nests found, 34 nests were in anthropogenic structures such as wall ledges, air condition mounts, window canopies, cable poles, guardrails, eaves, balcony frames, flowerpots and flower shelves on balconies. We found that the available anthropogenic nest sites and the available nesting trees were main factors determining the use of anthropogenic structures as nesting sites in common blackbirds. In urban environments, the amount of available anthropogenic nesting sites increased significantly, whereas the number of natural nesting sites reduced greatly. Our results suggest that common blackbirds can adjust their nest sites in response to urbanization and such nesting behavior shifts may aid them to colonize urban environments. From a management viewpoint, our results indicate that behavioral flexibility should be taken into account for effective urban wildlife management and conservation.

Exclusion of soil macrofauna did not affect soil quality but increased crop yields in a sub-humid tropical maize-based system

Soil macrofauna such as earthworms and termites are involved in key ecosystem functions and thus considered important for sustainable intensification of crop production. However, their contribution to tropical soil quality and crop performance, as well as relations with agricultural management (e.g., Conservation Agriculture), are not well understood. This study aimed to quantify soil macrofauna and its impact on soil aggregation, soil carbon and crop yields in a maize–soybean system under tropical sub-humid conditions. A field trial was established in Western Kenya in 2003 with tillage and residue retention as independent factors. A macrofauna exclusion experiment was superimposed in 2005 through regular insecticide applications, and measurements were taken from 2005 to 2012. Termites were the most abundant macrofauna group comprising 61% of total macrofauna numbers followed by ants (20%), while few earthworms were present (5%). Insecticide application significantly reduced termites (by 86 and 62%) and earthworms (by 100 and 88%) at 0–15 and 15–30cm soil depth respectively. Termite diversity was low, with all species belonging to the family of Macrotermitinae which feed on wood, leaf litter and dead/dry grass. Seven years of macrofauna exclusion did not affect soil aggregation or carbon contents, which might be explained by the low residue retention and the nesting and feeding behavior of the dominant termites present. Macrofauna exclusion resulted in 34% higher maize grain yield and 22% higher soybean grain yield, indicating that pest damage – probably including termites – overruled any potentially beneficial impact of soil macrofauna. Results contrast with previous studies on the effects of termites on plant growth, which were mostly conducted in (semi-) arid regions. Future research should contribute to sustainable management strategies that reduce detrimental impact due to dominance of potential pest species while conserving soil macrofauna diversity and their beneficial functions in agroecosystems.

Nesting Behavior and Colony Description of the Neotropical Bombus (Thoracobombus) brevivillus in Northeastern Brazil

Here we describe for the first time the nesting behavior and the colony of Bombus (Thoracobombus) brevivillus, a Neotropical species native only to South America. We discovered and observed seven B. brevivillus colonies between August and September 2012 in the state of Ceara, NE Brazil. Observations showed that B. brevivillus seems to be opportunistic in relation to nesting sites and brood protection, even though there is meager investment in nest building and offspring protection. Observations suggest that may be young B. brevivillus colonies invest strongly in brood production and colony development, before reproducing. More studies are necessary to evaluate the feasibility of captivity breeding of this species.

Nest and food search behaviour in desert ants, Cataglyphis: a critical comparison.

North African desert ants, Cataglyphis, use path integration to calculate a home vector during their foraging trips, constantly informing them about their position relative to the nest. This home vector is also used to find the way back to a productive feeding site the ant has encountered and thus memorized. When the animal fails to arrive at its goal after having run off the home or food vector, a systematic search is initiated. The basic search strategies are identical for nest and food searches, consisting of a search spiral superimposed by a random walk. While nest searches have been investigated in much detail, food site searches have received comparatively little attention. Here, we quantify and compare nest and food site searches recorded under similar conditions, particularly constant nest-feeder distance, and we observe notable differences in nest and food search performances. The parameters of nest searches are relatively constant and improve little with experience, although those small improvements had not been recognized previously. Food searches, by contrast, are more flexible and cover smaller or larger areas, mainly depending on the reliability of food encounter over several visits. Intriguingly, food site searches may be significantly more focussed than nest searches, although the nest should be the most important goal in an ant's life. These results demonstrate both adaptability and high accuracy of the ants' search programme.

Effects of emergence time and early social rearing environment on behaviour of Atlantic salmon: consequences for juvenile fitness and smolt migration.

Consistent individual differences in behaviour have been well documented in a variety of animal taxa, but surprisingly little is known about the fitness and life-history consequences of such individual variation. In wild salmonids, the timing of fry emergence from gravel spawning nests has been suggested to be coupled with individual behavioural traits. Here, we further investigate the link between timing of spawning nest emergence and behaviour of Atlantic salmon (Salmo salar), test effects of social rearing environment on behavioural traits in fish with different emergence times, and assess whether behavioural traits measured in the laboratory predict growth, survival, and migration status in the wild. Atlantic salmon fry were sorted with respect to emergence time from artificial spawning nest into three groups: early, intermediate, and late. These emergence groups were hatchery-reared separately or in co-culture for four months to test effects of social rearing environment on behavioural traits. Twenty fish from each of the six treatment groups were then subjected to three individual-based behavioural tests: basal locomotor activity, boldness, and escape response. Following behavioural characterization, the fish were released into a near-natural experimental stream. Results showed differences in escape behaviour between emergence groups in a net restraining test, but the social rearing environment did not affect individual behavioural expression. Emergence time and social environment had no significant effects on survival, growth, and migration status in the stream, although migration propensity was 1.4 to 1.9 times higher for early emerging individuals that were reared separately. In addition, despite individuals showing considerable variation in behaviour across treatment groups, this was not translated into differences in growth, survival, and migration status. Hence, our study adds to the view that fitness (i.e., growth and survival) and life-history predictions from laboratory measures of behaviour should be made with caution and ideally tested in nature.

Staying high and dry: a unique nesting strategy for an insular iguana

Staying high and dry: a unique nesting strategy for an insular iguana

First description of a nest of the Rufous-tailed Antthrush Chamaeza ruficauda

I report a nest of Rufous-tailed Antthrush discovered on 9 December 1998 in the Serra dos Orgaos National Park, Rio de Janeiro, Brazil at the altitude of 1950 m. The nest was located in a natural tree cavity with vertically-elliptical entrance hole ca. 5 m above the ground. It was a thick pad of piled bamboo leaves, leathery tree leaves, fungal rhizomorphs, grass, and a piece of cellophane. The nest contained two nearly fully-grown nestlings, which were fed by both parents. The architecture of the nest and parental behavior are compared to those of other antthrushes.

Age, fertility and reproductive behavior in cuban crocodiles, Crocodylus rhombifer, at the Smithsonian's National Zoological Park.

The Smithsonian's National Zoological Park (NZP) has a long history with Cuban crocodiles, Crocodylus rhombifer, beginning in 1900's when the first animals arrived at the NZP. Today, the Zoo has two breeding groups of C. rhombifer and has observed and analyzed reproductive behavior and fertility rates over the last three years. Fertility rates were determined initially by observing the formation of an opaque band that forms on the shell of a fertile egg, called banding. The fertility rates by banding were later compared to the observation made after opening the eggs to verify fertility. In addition to tracking fertility, nesting and agonistic behavior were also observed. Several notable observations were documented over the same period. These included a male predating a nesting female's eggs, increased aggression between two females housed together, the continued development of a partially banded egg, and the discovery of 19 additional egg shells post oviposition by both females in the enclosure. Here we discuss the nest phenology, fertility and behavior of the five exhibited C. rhombifer at the Smithsonian's National Zoological Park over a 3-year period. Zoo Biol. 34:278-284, 2015. © 2015 Wiley Periodicals Inc.

Strategic use of straw increases nest building in loose housed farrowing sows

In spite of domestication, sows are still genetically programmed to perform nesting behaviour close to farrowing. In order to facilitate nest building, a method for a strategic use of large quantities of straw has been developed by Swedish piglet producing farmers. The objectives of the present study were to quantify the effect of strategic use of 15–20kg of chopped straw given once 2 days prior to expected date of farrowing, compared to small daily amounts (0.5–1kg) and 2kg close to farrowing (controls), on the nest building behaviour and the duration of farrowing. The behaviour from 18h pre-partum until 1h after birth of first piglet and the duration of farrowing was continuously observed in 138 video recordings from 4 commercial farms. On each farm, 20–34 sows (parity≥2) were studied during one or two consecutive lactations. Compared to controls, strategic use of straw triggered the sows to start nest building earlier and increased the total time spent nest building pre-partum by 19% (p=0.039). Sows given large amounts of straw also performed less nesting behaviours during the first hour after birth of the first piglet. This shows that nest building is affected not only by the presence of straw, but also by the quantity of straw provided, and that 2kg of chopped straw seems to be too little to make the sow terminate nest building well in advance of farrowing. There was no significant effect of treatment on the duration of farrowing but a strong negative association was found between time spent nest building pre-partum and the duration of farrowing regardless of treatment. The model predicted a 1-h increase in total nest building time pre-partum to be associated with a 12% (95% CI=4–19%) shorter duration of farrowing (p=0.004).