SEARCH · PubMed Health

Results for “Nesting Behavior”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 685 records · Page 38Linked to original sources

PubMed2001

Chlorinated hydrocarbons and biomarkers of exposure in wading birds and fish of the lower Rio Grande Valley, Texas.

During 1997 we evaluated reproductive success in colonial water birds nesting in the Lower Rio Grande Valley (LRGV), Texas, and correlated success with concentrations of contaminants in eggs. We also measured steroid hormones and gonadosomatic index (GSI) as biomarkers of endocrine effects in common carp (Cyprinus carpio). Nest and fledging success of green herons (Butorides virescens) and great egrets (Ardea alba) were similar to those found in other parts of North America; however, nesting success of black-crowned night-herons (Nycticorax nycticorax) was lower, very likely due to flooding of the nesting area. Except for DDE and toxaphene, all chlorinated pesticides in bird eggs were low and not of concern for negative effects on any of the three species. DDE was highest in green heron eggs and seemed to increase along a geographic gradient from west to east, with eggs from Falcon Reservoir containing low concentrations, and those at Los Indios containing the highest concentrations (approx. 11,000 ng/g WW), near or above the threshold for reproductive impairment. DDE levels in great egrets and black-crowned night-herons were below those that are associated with reproductive impairment. Mean DDE levels in carp at the JAS Farms site were above the threshold level suggested for predator protection. Toxaphene was detected in about 20% of the samples with high levels observed in green heron eggs from Los Indios (mean = 4,402 ng/g WW). These are the highest toxaphene levels reported in bird eggs in the LRGV. Toxaphene levels in fish ranged between 90 and 312 ng/g WW. In general, PCBs in bird eggs and fish tissue were low and at levels not of concern for reproductive effects. The greatest concentrations of testosterone and 11-ketotestosterone were detected in fish from the JAS Farms site, which also had the greatest concentrations of DDE. Increased androgen production and gonad development in fish at this site, relative to Pharr, could be possibly associated with endocrine disrupting effects of p,p'-DDE. DDE, toxaphene, PCBs, and hormones were highest in birds and fish from the eastern edge of the study area.

Abnormalities, Drug-Induced↗

PubMed2006

Use of artificial roost structures by bats at the Indianapolis International Airport.

From 1992-1996, 3204 artificial roosts of 9 types were placed in woodlots near Indianapolis International Airport in an effort to provide habitat for the federally-endangered Indiana myotis (Myotis sodalis) and to determine the feasibility of using these structures to manage bats in a rapidly developing suburban area. We surveyed these structures at least annually during 1992-1999 and found only northern myotis (Myotis septentrionalis) regularly using the structures. Four other species were occasionally found using structures including big brown bats (Eptesicus fuscus, n=14 individuals), little brown myotis (Myotis lucifugus, n=2), Indiana myotis (Myotis sodalis, n=2), and one silver-haired bat (Lasionycteris noctivagans). Single, triple, and Missouri-style batboxes were almost always used, rather than the six other types of experimental roosts that had been in place. However, after 10 years in place, it appears that Indiana bats are acclimated to boxes, as 6 of them were being used rather regularly by Indiana myotis. Bat boxes can provide roosting habitat for some species under conditions where few suitable roosts exist, but assuring an abundance of natural habitats is usually more desirable for conservation of tree-roosting bats.

Acclimatization↗

PubMed2006

Distorting gene pools by conservation: Assessing the case of doomed turtle eggs.

Sea turtles have a high reproductive output and high mortality at early stages of the life cycle. In particular, many nests are laid below or close to high tide lines, and subsequently large numbers of eggs may be inundated and destroyed. A common conservation procedure is to relocate such doomed eggs to higher ground. This article examines this practice in the light of recent data revealing that some individual turtles tend to nest relatively near the water and others relatively higher up the beach. Discussion is focused on the question of why apparently poor placement of nests has not been selected against. Comparison between the ecology of leatherback and hawksbill turtle nesting beaches suggests that predictability of environmental conditions on the nesting beaches has an important influence on patterns of nest-site selection. Options are outlined for the management of nesting beaches where a high proportion of turtle eggs is subject to destruction by flooding.

Animals↗

PubMed2001

Integrating nonindigenous aquatic plant control with protection of snail kite nests in Florida.

The endangered snail kite (Rostrhamus sociabilis) feeds primarily on the freshwater apple snail (Pomacea paludosa) in Florida. The nonindigenous, floating water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes) impede kites from finding snails. Effective control of these aquatic plants in the littoral zone of central and south Florida lakes benefits kites by maintaining open foraging habitat. However, incidental herbicide spraying of nesting substrates result in nest collapse when kites breed in nonwoody, emergent plants [cattail (Typha spp.) and giant bulrush (Scirpus validus)] in the outer littoral zone during lower lake levels. Many endangered species recovery plans and their implementation have experienced problems due to inaction and/or noncooperation by various governmental agencies and their personnel. Herein, we describe the development and implementation of a buffer zone strategy to prevent secondary impacts from an aquatic plant control program to snail kites nesting on lakes in central and south Florida. A strategy was jointly developed by personnel of five state and federal agencies to control herbicide application near kite nesting areas during the normal breeding season. Although requiring various modifications during its implementation, this cooperative effort successfully integrated aquatic plant control objectives with snail kite conservation on Lake Okeechobee during 1988. The program was expanded the following year to lakes Kissimmee and Tohopekaliga. Since the implementation of the snail kite impact preclusion program, no nest loss was attributed to incidental herbicide applications on lakes Okeechobee, Kissimmee, and Tohopekaliga.

Animals↗

PubMed2000

Task-related variation of postpharyngeal and cuticular hydrocarbon compositions in the ant Myrmicaria eumenoides.

In the ant Myrmicaria eumenoides we investigated postpharyngeal and cuticular hydrocarbons. At eclosion the glands contained almost no hydrocarbons and there were no lipid inclusions in the glandular epithelium. During the first 3 weeks of adult life the amount of hydrocarbons in the gland increased until day 5, and then remained constant while the lipid content in the epithelium increased steadily. Intracolonial hydrocarbon compositions were not uniform. Compositions of post-pharyngeal and cuticular hydrocarbons in individual ants varied simultaneously, but in different manner depending on the tasks of the ant (brood-tenders, foragers, scouts). Variations on the cuticle were greater than in the gland, but they were strongly correlated. Independent of ants' age and task, cuticular hydrocarbon compositions were dominated by alkenes and alkadienes. Task-specific differences in cuticular compositions were mainly in the amount of alkenes (high in foragers) and alkadienes (high in brood-tenders). Variation of hydrocarbons was low in ants up to 10 weeks old. Thereafter, ants fell into two groups: (1) ants that did not change their hydrocarbons and remained in the nest, and (2) ants that changed their hydrocarbon compositions and became foragers. These results contribute to an ongoing discussion of the dynamic relationship between post-pharyngeal and cuticular hydrocarbons.

Age Factors↗

PubMed2000

Radius construction and structure in the orb-web of Zilla diodia (Araneidae).

In orb-webs, the tension of the sticky spiral produces a centripetal force on the radii, resulting in an increase in tension along each radius from the centre of the web to the periphery. Zilla diodia (Walckenaer, 1802) atypical of araneids, was found to adapt the structure of its radii to this tension gradient by building radii that are double stranded at the periphery of the web and single stranded near the centre. Furthermore, the proportion of each radius that is doubled was found to be larger in the upper part of the web - where the overall tensions in the radii are known to be higher than in the lower part of the web. suggesting that the spider adjusts the proportion of each radius that is doubled to the overall tension in the radius.

Animals↗

PubMed2002

Simple roost nests confer large energetic savings for sparrow-weavers.

White-browed sparrow-weavers (Plocepasser mahali, body mass 40 g) are group-living passerines adapted to the semi-arid environment of north-eastern and south-western Africa. During winter, the nocturnal ambient temperature of these regions often falls below 0 degrees C. imposing conditions demanding an increase in thermoregulatory heat production. Individuals roost throughout the year in inverted U-shaped roost nests. We investigated the energetic advantages of roosting by measuring nest and ambient temperatures in the field, as well as the resting metabolic rate (RMR) of the birds. The sparrow-weavers exhibited a wide thermoneutral zone (13 degrees C - 32 degrees C). Although RMR at thermoneutrality (40.2 J g.h(-1)) conforms with those of other passerines. the value at 0 degrees C (74.8 J g.h(-1)) is significantly lower than expected. The slope of the line below the lower critical temperature is unexpectedly steep, however, and appears to cause the physiological requirement for nest roosting due to a high cost of thermoregulation at low temperatures, perhaps due to shivering or non-shivering thermogenesis. The nest temperature at 0 degrees C ambient is 5 degrees C. resulting in a saving of some 7% in the energy spent during winter nights when food resources are in short supply compared with the rest of the year.

Acclimatization↗

PubMed2005

Correlates of oxidative stress in wild kestrel nestlings (Falco tinnunculus).

The fitness of an organism can be affected by conditions experienced during early development. In light of the impact that oxidative stress can have on the health and ageing of a bird species, this study evaluated factors accounting for the variation in oxidative stress levels in nestlings of the Eurasian kestrel (Falco tinnunculus) by measuring the serum concentration of reactive oxygen metabolites and the serum antioxidant barrier against hypochlorite-induced oxidation. The ratio between these two variables was considered as an index of oxidative stress, with higher values meaning higher oxidative damage. Six-chick broods showed the highest level of oxidative stress, while no effect of sex was found. Age showed an inverse relationship with the oxidants and the levels of oxidative stress, with younger birds having higher levels. Hatching date, body condition, body mass and carotenoid concentration did not show any relationship with oxidants, antioxidants or degree of oxidative stress. These findings suggest that intrabrood sibling competition could play a role in determining oxidative stress, and that in carnivorous birds other antioxidant molecules could be more important than carotenoids to reduce oxidative stress.

Animals↗

PubMed2006

Do geese fully develop brood patches? A histological analysis of lesser snow geese (Chen caerulescens caerulescens) and Ross's geese (C. rossii).

Most birds develop brood patches before incubation; epidermis and dermis in the brood patch region thicken, and the dermal connective tissue becomes increasingly vascularized and infiltrated by leukocytes. However, current dogma states that waterfowl incubate without modifications of skin within the brood patch region. The incubation periods of lesser snow geese (Chen caerulescens caerulescens; hereafter called snow geese) and Ross's geese (C. rossii) are 2-6 days shorter than those of other goose species; only females incubate. Thus, we hypothesized that such short incubation periods would require fully developed brood patches for sufficient heat transfer from incubating parents to eggs. We tested this hypothesis by analyzing the skin histology of abdominal regions of snow and Ross's geese collected at Karrak Lake, Nunavut, Canada. For female snow geese, we found that epidermis and dermis had thickened and vascularization of dermis was 14 times greater, on average, than that observed in males (n=5 pairs). Our results for Ross's geese (n=5 pairs) were more variable, wherein only one of five female Ross's geese fully developed a brood patch. Our results are consistent with three hypotheses about brood patch development and its relationship with different energetic cost-benefit relationships, resulting from differences in embryonic development and body size.

Animals↗

PubMed2006

Environmental and genetic components of oxidative stress in wild kestrel nestlings (Falco tinnunculus).

In this study, we estimated the environmental and genetic components of two variables related to avian oxidative stress using wild nestlings of the Eurasian kestrel (Falco tinnunculus). The study was carried out during two breeding seasons. In the first season, we assessed the between- and within-nest resemblance in serum reactive oxygen metabolites (ROMs) and total serum antioxidant barrier (OXY). In the second season, we carried out a cross-fostering experiment to determine the importance of environmental and genetic factors on ROMs and OXY. The 23.5% of ROMs variance was explained by the nest of origin, indicating a main genetic component. In contrast, the 52.8% of OXY variance was explained by the nest of rearing, indicating that this variable was more influenced by environmental components. These findings suggest that variations in ROMs and OXY could reflect, respectively, the expression of different genetic polymorphisms and differences in dietary uptake of antioxidants.

Animals↗

PubMed2006

Patterns of serum carotenoid accumulation and skin colour variation in kestrel nestlings in relation to breeding conditions and different terms of carotenoid supplementation.

Carotenoids are pigments synthesised by autotrophic organisms. For nestlings of raptorial species, which obtain carotenoids from the consumption of other heterotrophic species, the access to these pigments can be crucial. Carotenoids, indeed, have fundamental health maintenance functions, especially important in developing individuals as nestling kestrels. The aim of this study was to investigate how body carotenoid levels and skin pigmentation vary in kestrel nestlings (Falco tinnunculus) in relation to nesting parameters. Furthermore, we experimentally altered carotenoid availability (short- medium- and long-term) for nestlings and investigated skin and serum variance. The skin colour variance of 151 nestlings was explained by nest of origin, age and by the body condition (body mass corrected by age), older nestlings with higher body condition being redder. No difference in skin colour was detected between sexes. Differences in hue (skin "redness") between treatments did not emerge during the first week, but did occur 15 days after administration between long-term supplemented and control chicks. In contrast, the serum carotenoid concentration showed a treatment-dependent increase after 5 days from the first carotenoid administration and at least after two supplemented feedings. In general, hue but not serum carotenoids, was correlated with the body condition of nestlings. Based on the increased skin pigmentation of nestling kestrels in the long-term experimental group, we suggest carotenoid availability to be limited for colour expression. The small increase of serum carotenoids due to supplementation is consistent with the hypothesis that there is a physiological constraint on these pigments, as well as an environmental limitation. The presented results are useful for the understanding of carotenoid uptake and accumulation by a wild raptorial species, located at the top of the food web, highlighting that carotenoids are a limited resource for kestrel nestlings.

Age Factors↗

PubMed2000

Body reserves and nutritional needs during laying preparation in barn owls.

To investigate the composition of the body reserves made during pre-laying by breeding European barn owls (Tyto alba), we have analysed the body composition of captive breeding and non-breeding females sacrificed during the laying period. The data obtained were compared to the daily requirement for egg formation obtained by an egg composition analysis and the timing of egg synthesis. This study demonstrates that body mass gain observed in breeding females (+ 38.3 g after eggs in formation and gonadal tractus were removed) was not the consequence of an accumulation of body fuels like lipids but of mainly water and lean material. The lipidic reserves were found to be less important in breeding than in non-breeding females and their localisation modified; lipids were absent from medullar bones in breeding females which liberated room for other storage. The subcutaneous tissue, which was homogeneous in non-breeding females, was located principally under the brood patch in breeding females. Nutrients and energy required during egg formation could be obtained without modification of daily food intake. These results show that a laying event can be initiated in 14 days and that the onset of reproduction is not triggered by body condition in barn owls. The water accumulation observed is suggested to be the mere consequence of an increase of protein metabolism (egg and moult). These results intimate that the body mass increase observed in diurnal and nocturnal raptors during laying preparation, interpreted as an energy safety strategy, ought to be reconsidered.

Animal Nutritional Physiological Phenomena↗

PubMed2003

Analysis of avian communities in Lake Guri, Venezuela, using multiple assembly rule models.

This study analyzed the distribution of resident, forest-interior bird species nesting on islands in Lake Guri, Venezuela using several different community assembly rule models. The models that were tested included Diamond's Assembly Rules, Size Structure, Guild Proportionality, Favored States, and Nestedness. It was determined that the species composition of the study communities was only weakly influenced by competition, but that competition did appear to limit the size similarity which is permissible for co-occurring species. There was no tendency for the relative proportion of species within guilds (i.e. insectivore, omnivore, nectivore and frugivore) to remain stable among the islands. When only the insectivorous and omnivorous species were analyzed (using feeding strata as the functional groups) there was some support for the guild proportionality hypothesis. This study found no support for Fox's Favored State hypothesis, possibly due to the overrepresentation of insectivores and omnivores in the species pool. The island communities exhibit a highly nested structure. This high degree of nestedness supports the hypothesis that the assemblages are more strongly determined by differential extinction vulnerability and selective species loss than by interspecific or inter-guild competition. Understanding patterns of community assembly and their underlying forces has important implications for conservation ecology and reserve design.

Animals↗

PubMed2003

Carotenoid-based colour expression is determined early in nestling life.

Carotenoid-based colours are widespread in animals and are used as signals in intra- and interspecific communication. In nestling birds, the carotenoids used for feather pigmentation may derive via three pathways: (1) via maternal transfer to egg yolk; (2) via paternal feeds early after hatching when females are mainly brooding; or (3) via feeds from both parents later in nestling life. We analysed the relative importance of the proposed carotenoid sources in a field experiment on great tit nestlings ( Parus major). In a within-brood design we supplemented nestlings with carotenoids shortly after hatching, later on in the nestling life, or with a placebo. We show that the carotenoid-based colour expression of nestlings is modified maximally during the first 6 days after hatching. It reveals that the observed variation in carotenoid-based coloration is based only on mechanisms acting during a short period of time in early nestling life. The experiment further suggests that paternally derived carotenoids are the most important determinants of nestling plumage colour.

Adaptation, Physiological↗

PubMed2004

Egg size and offspring performance in the collared flycatcher ( Ficedula albicollis): a within-clutch approach.

Adaptive within-clutch allocation of resources by laying females is an important focus of evolutionary studies. However, the critical assumption of these studies, namely that within-clutch egg-size deviations affect offspring performance, has been properly tested only rarely. In this study, we investigated effects of within-clutch deviations in egg size on nestling survival, weight, fledgling condition, structural size and offspring recruitment to the breeding population in the collared flycatcher ( Ficedula albicollis). Besides egg-size effects, we also followed effects of hatching asynchrony, laying sequence, offspring sex and paternity. There was no influence of egg size on nestling survival, tarsus length, condition or recruitment. Initially significant effect on nestling mass disappeared as nestlings approached fledging. Thus, there seems to be limited potential for a laying female to exploit within-clutch egg-size variation adaptively in the collared flycatcher, which agrees with the majority of earlier studies on other bird species. Instead, we suggest that within-clutch egg-size variation originates from the effects of proximate constraints on laying females. If true, adaptive explanations for within-clutch patterns in egg size should be invoked with caution.

Animals↗

PubMed2004

Correlates of lifetime reproductive success in three species of European ducks.

Number of breeding attempts is a strong correlate of lifetime reproductive success (LRS) in birds, but the relative importance of potentially interacting factors affecting LRS has rarely been fully evaluated. We considered simultaneously five main factors hypothesized to influence LRS (age at first breeding, nesting date, number of breeding attempts, female traits, brood parasitism) by analyzing with path analysis 22-year data sets for 1,279 individually marked females and their offspring in tufted duck ( Aythya fuligula), common pochard ( A. ferina) and northern shoveler (Anas clypeata). We recaptured marked offspring as breeding adults (n=496 females) and obtained more complete estimates of LRS by incorporating information about banded ducklings of both sexes shot by hunters > or =12 months after banding (n=138). In tufted ducks and especially pochard (both diving duck species), late-hatched females tended to delay nesting until 2-years old. Most females (tufted duck, 74%; pochard, 71%; shoveler, 59%) apparently produced no breeding-age offspring. Number of breeding attempts (i.e., longevity) was the strongest correlate of LRS in all species, after controlling effects of age at first breeding, relative nest initiation date, wing length and body mass. Percentage of females producing recruits increased gradually with number of breeding attempts for all three species. Also, as expected, females nesting early in the breeding season had higher LRS than late-nesting individuals. In shoveler, female-specific characteristics of relatively longer wings and heavier late incubation body mass had positive effects on LRS, the latter feature being more common in 2-year-old nesters. In diving ducks, no relationships were detected between LRS and female-specific traits like wing length or body mass, and nor did acceptance of parasitic eggs have any deleterious impact on fitness estimates. Overall, number of fledged ducklings and LRS were related in tufted duck, weakly associated in pochard and unrelated in shoveler, implying that fledging success is not always a reliable measure of LRS.

Animals↗

PubMed2004

Hatching asynchrony in Burrowing Owls is influenced by clutch size and hatching success but not by food.

In most animals, siblings from a given reproductive event emerge over a very short period of time. In contrast, many species of birds hatch their young asynchronously over a period of days or weeks, handicapping last-hatched chicks with an age and size disadvantage. Numerous studies have examined the adaptive significance of this atypical hatching pattern, but few have attempted to explain the considerable intrapopulation variation that exists in hatching asynchrony. I explored proximate determinants of hatching asynchrony by monitoring 112 Burrowing Owl (Athene cunicularia) nests in the grasslands of southern Saskatchewan, Canada, over 4 years. Age disparities between first- and last-hatched siblings (i.e., hatching spans) varied considerably, ranging between 1 and 7 days (mode = 4 days). These hatching spans increased with increased hatching success. Hatching spans also increased with larger clutches, but the increase was less than predicted given the increased time required to lay more eggs. Hatching span was unrelated to number of prey cached in the nest during egg laying (an index of food availability), and was unaltered by a year of super-abundant prey. Furthermore, pairs given extra food during laying had hatching spans equal to those of unsupplemented control pairs. These results were inconsistent with both the energy constraint and facultative manipulation hypotheses, which predict that hatching asynchrony should vary with the level of food during laying, when incubation onset is determined. Burrowing Owls were apparently free of food limitation early in breeding, yet may not have been able to optimize hatching spans because food conditions during laying were largely unrelated to food conditions during brooding. Thus, one of the premises for facultative manipulation of hatching asynchrony-that laying females are able to forecast post-hatch food conditions-may not have been met for this population of Burrowing Owls.

Analysis of Variance↗

PubMed2005

Effects of climate variation on timing of nesting, reproductive success, and offspring sex ratios of red-winged blackbirds.

Predicting ecological consequences of climate change will be improved by understanding how species are affected by contemporary climate variation, particularly if analyses involve more than single ecological variables and focus on large-scale climate phenomena. I used 18 years of data from red-winged blackbirds (Agelaius phoeniceus) studied over a 25-year period in eastern Ontario to explore chronological and climate-related patterns of reproduction. Although blackbirds started nesting earlier in years with warmer springs, associated with low winter values of the North Atlantic Oscillation Index (NAOI), there was no advance in laying dates over the study. Nesting ended progressively later and the breeding season lasted longer over the study, however, associated with higher spring values of NAOI. As the length of the nesting season increased, offspring sex ratios became more female biased, apparently as a result of females adjusting the sex of the eggs they laid, rather than from sex-biased nestling mortality. Clutch size did not vary systematically over the study or with climate. Opposing trends of declining nest success and increasing productivity of successful nests over the study resulted in no chronological change in productivity per female. Higher productivity of successful nests was associated with higher winter NAOI values, possibly because synchrony between nesting and food availability was higher in years with high NAOI values. Other than the association between the start of nesting and spring temperatures, local weather (e.g., temperature, rainfall) patterns that linked NAOI with reproduction were not identified, suggesting that weather patterns may be complex. Because climate affected most aspects of red-winged blackbird reproduction examined, focusing on associations between climate and single variables (e.g., first-egg dates) will have limited value in predicting how future climates will affect populations.

Animals↗