Nest Destruction Research Articles

Effectiveness of mesh netting and nest’ destruction in protection of crops against attack by Spanish sparrow Passer hispaniolensis

Many developing countries are rich in natural resources such as high quality, cultivated land, but still depend on imports to meet domestic demand for basic products. One of the factors constraining production of cereal crops in many countries is the damage caused by seed-eating birds such as sparrows. The aim of this study was to test the effectiveness of two methods, deployment of netting and destruction of sparrow nests, in protecting crops and decreasing harvest losses. In two years (2006 and 2009), potential wheat yield and sparrow damage were assessed in two experimental plots of wheat plus a third control plot. The average percentage of ears attacked by the Spanish sparrow in the control plot was 62±4.9%. This was significantly higher than the levels of sparrow damage in the nest destruction plot (35±2.3%) and the plot protected by netting (1.4±0.35%). The theoretical yield was estimated to be 1452±180 kg/ha in the control plot, 1318±126 kg/ha in the nest destruction plot, and 1928±117 kg/ha in the netting plot. This study demonstrates that yield losses of Algerian wheat can be substantially reduced using simple and cost-effective techniques. Key words: Spanish sparrow, nests destruction, loss, wheat.

Mass nesting of olive ridley sea turtles Lepidochelys olivacea at La Escobilla, Mexico: linking nest density and rates of destruction

Olive ridley sea turtles Lepidochelys olivacea exhibit synchronized nesting behavior that affects egg survival through a variety of mechanisms, including intra-specific nest destruc- tion. This activity is difficult to quantify due to the frequency of arribadas (mass nesting events that occur over several days) and temporal overlap of incubation periods. We hypothesized that nest destruction is positively related to cumulative nest density. We quantified these variables through direct observation of nesting by 1293 turtles in 26 plots (each 9 m 2 ) during 2 arribadas at La Escobilla, Mexico, in 2009. Cumulative nest densities ranged from 1 to 8 nests m �2 . The propor- tion of turtles observed destroying eggs was used as a proxy for nest destruction. A total of 5.12 and 23.10% of turtles destroyed eggs in the first and second arribadas, respectively. We used a mixed model logistic regression to determine that the odds of destruction (or the probability that a turtle destroys eggs divided by the probability that she does not) increased 21% for every addi- tional nest per square meter. We could not measure total egg survival as a function of nest density likely due to extreme weather conditions and beetle predation that resulted in 0% hatchling pro- duction over most of the study area in August to October 2009. However, understanding the rela- tionship between nest density and the probability of nest destruction is an important first step toward quantifying density dependence in olive ridleys. We recommend that monitoring plans include standardized measurements of density (nests per square meter) and destruction levels to improve estimates of annual hatchling production.

The effectiveness of conservation measures to enhance nest survival in a meadow bird suffering from anthropogenic nest loss

The main reason for meadow bird declines is supposed to be the intensification of grassland management with earlier first harvest dates and more frequent harvests, resulting in high nest destruction rates. To increase productivity of meadow bird populations in intensified grassland areas a delay of mowing date and individual nest protection measures have been proposed. However, for ground-nesting songbirds such as the whinchat (Saxicola rubetra) the effectiveness of such measures remains widely unknown. In particular, if nest predation rate is high, measures to protect nests from agricultural destruction alone might be questionable. Here, we quantify whinchat nest survival of (1) unprotected nests situated in early mown meadows, (2) protected nests situated in early mown meadows, and (3) nests situated in late mown meadows. Analyses considered the fact that successful and unsuccessful nests are not found with equal probabilities. Periods of reduced nest survival were associated with mowing periods in the different types of meadows. In early mown meadows nest survival rates were low (S<0.1), and both conservation measures, individual nest protection and delayed mowing, resulted in significantly increased nest survival rates (S>0.7). Individual nest protection cannot avoid changes in habitat quality of intensively managed meadows, and therefore is only suitable as small-scale and short-term measure to increase nest success until a high portion of late mown meadows is established. Thus, we suggest that a combination of the two measures applied to intensified grassland fields should be provided to maintain viable sizes of endangered meadow bird populations.

Responses of Nesting Yellow-Headed Blackbirds and Yellow Warblers to Wrens

Abstract We studied nest defense behavior of Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) and Yellow Warblers (Dendroica petechia) in response to two species of common nest destroyers. We presented freeze-dried models of Marsh Wrens (Cistothorus palustris) at Yellow-headed Blackbird nests and House Wrens (Troglodytes aedon) at Yellow Warbler nests during the incubation stage. We presented a Clay-colored Sparrow (Spizella pallida) as a control for both species. Male Yellow-headed Blackbirds responded more intensively to the Marsh Wren model than the control and female blackbirds responded intensively to both models but were more aggressive toward the Marsh Wren. Most Yellow Warblers did not respond to the House Wren model with their typical predator responses (e.g., alarm calls). Some female warblers were aggressive toward the wren model, whereas others sat in their nest. Sitting in the nest as a defense to deter nest destruction by House Wren needs further investigation. Differences in respons...

Brood ranging behaviour and breeding success of the threatened little bustard in an intensified cereal farmland area

Cereal pseudo-steppes hold the largest proportion of declining bird species in Europe. Understanding how this process of decline is driven is essential for designing adequate management practices. The little bustard (Tetrax tetrax) is one of such threatened steppe-land bird species, which has suffered recent dramatic range constrictions and population declines. Although low breeding success has been claimed to be the main threat for the viability of future little bustard populations, the surprising lack of studies dealing with ecological requirements of broods hinders the implementation of efficient conservation practices. We studied the ranging behaviour and the reproductive success of a little bustard population by means of female radio-tracking conducted during 2006–2008 breeding seasons in the Ebro basin (NE Spain). We recorded an average breeding success of 0.27 chicks/hen, which is not enough to sustain a viable population according to the demographic models for the species. Early-laid clutches showed more probabilities to hatch and to fledge. This was associated to two different ranging patterns (i.e. sedentary versus wandering respectively) which depended on the ability of the hen and its chicks to settle in suitable areas harbouring enough arthropods and shelter for chicks. Such resources decrease drastically as the breeding season progresses. Overall, data suggest that agricultural practices associated to agricultural intensification, particularly early harvest, reduce breeding success both directly by nest destruction and indirectly through a decrease on resource availability for broods. Based on our findings on the characteristics and structure of the home range of little bustard broods, we propose the creation of a network of permanent vegetation plots interconnected by high-quality field margins as a management practice to raise the breeding success of little bustards and other ground-nesting birds on cereal farmland.

Morphometric characteristics of Formica aquilonia ants in monitoring of their settlements

The variability of size, chaetotaxy, the petiole shape, and mandible dentition in workers of F. aquilonia was studied in the Verkhnyaya Klyazma Myrmecological Preserve (Moscow Province, Russia), where populations of red wood ants (F. aquilonia, F. polyctena, and F. lugubris) have been monitored since 1966. Comparative analysis of samples from two different F. aquilonia settlements (A1 and A21S) showed that workers from A1 had a smaller size and more abundant pilosity. The variability of the molar margin of the mandibles was similar in the two settlements while the petiole shape differed. Comparison of three generations of workers from A1 (the seasons of 1969, 1986, and 1992) revealed significant changes in their phenotype (a decrease in size and an increase in pilosity and asymmetry) which coincided with the settlement degradation after mass destruction of ant nests by poachers, wild boars, and woodpeckers in 1977–1985.

Rapid recovery of a depleted population of Little Bustards Tetrax tetrax following provision of alfalfa through an agri‐environment scheme

The Little Bustard has undergone a steep reduction of its Western Palaearctic range over the last century. In the west of France, breeding populations declined by 96% from 1978 to 2008 in cultivated areas where grasslands have been converted into intensively managed annual crops. Little Bustard abundance and nest productivity have been monitored since 1995 in a 450‐km2 site in western France. We assessed the proximate causes of the decline of Little Bustards in French farming landscapes and quantified the effectiveness of conservation measures that aimed to reverse the decline. The decline of Little Bustard, from about 65 males in 1995 to just six males in 2003, could be related to a near absence of recruitment over this period. Since 2004, the establishment of more than 1300 ha of specifically targeted agri‐environment schemes (AES) in the study site has led to a sharp increase in female productivity, mainly associated with nesting in AES fields. By imposing constraints on mowing dates, AES have prevented nest destruction and female mortality during mowing and, by increasing plant species diversity, provided chicks with a higher abundance of grasshoppers. This has contributed to reversing the trend, and increasing the population to around 30 males in 2009. Conservation strategies involving specifically targeted AES based on the identification of limiting factors can help to reverse the decline of threatened species.

Estimating carrying capacity at the green turtle nesting beach of East Island, French Frigate Shoals

Many sea turtle populations are at a fraction of their historical abundance, and under- standing ecological processes, under current and climate change scenarios, is critical for establishing recovery goals. In the Hawaiian Islands, the nesting population of the green turtle Chelonia mydas on East Island, French Frigate Shoals, has been recovering at a rate of 5.7% per year. Climate change models, however, predict a loss in nesting habitat on East Island of up to 30% due to sea level rise by 2100. Therefore, the objective of the present study was to determine the carrying capacity of East Island for hatchlings and nesting females under current conditions and predictions of sea level rise. In the simulation model, density-dependent nest destruction was the primary factor regulating population size. Carrying capacity was reached between 1.9 and 2.1 million hatchlings at current conditions; carrying capacity was approached when 80 000 to 120 000 nests were laid on the beach, representing 20 000 to 30 000 nesting females. With a rise in sea level, carrying capacity was reached when 60 000 to 100 000 nests were laid on the beach. The current mean estimate of 390 nesting females per year, over the past 10 yr, at East Island represents 1.3 to 2% of the females that would nest at carrying capacity. The beach at East Island is well below carrying capacity and is capable of supporting a larger nesting population. However, the availability of suitable coastal habitats may play a bigger role in regulating the Hawaiian green turtle population than available nesting habitat.

Species conservation on human‐dominated landscapes: the case of crowned crane breeding and distribution outside protected areas in Uganda

AbstractSpecies primarily dependent on habitats outside protected areas have to cope with the direct pressure of human utilization or harassment, and the indirect pressure of habitat modification. In Uganda, wetlands mainly used by cranes occur mostly outside protected areas. The country’s wetlands are however under heavy modification, and this and other pressures are thought to have reduced crane populations to 10–30% of the number in the early 1970s. From January 2005 to January 2006, we assessed the status of crane breeding and distribution in the country. Breeding and foraging sites were assessed through a nationwide newspaper survey, and visits to wetlands. We established occurrence of 21 nests during the study period, and crane use of 27 out of 30 districts surveyed. Crane harassment and trapping were common during breeding, as was crop damage by cranes. This is the first attempt to show the distribution of crane breeding outside protected areas throughout the country. In addition to maintaining suitable breeding habitat, survival of cranes in Uganda lies in part in community engagement and punishing crimes related to hunting and destruction of nests.

Lowland Farmland Birds III: Delivering Solutions in an Uncertain World. A report on the BOU’s Annual Conference held at the University of Leicester, 31 March–2 April 2009

Lowland Farmland Birds III: Delivering Solutions in an Uncertain World. A report on the BOU’s Annual Conference held at the University of Leicester, 31 March–2 April 2009

Nest‐site selection by Great Bustards Otis tarda suggests a trade‐off between concealment and visibility

Great Bustards Otis tarda have expanded their habitat range from historical occupancy of natural steppes to arable farmland, where the species initially benefited from favourable feeding conditions. More recently, the species has suffered severe declines due partly to agricultural intensification. Nest losses and juvenile mortality are amongst the factors most seriously affecting survival probabilities of many populations of this endangered species, suggesting that management of nesting habitats would bring conservation benefits. We studied nest‐site selection in a Great Bustard population of central Spain by radiotracking 42 females for periods of between 1 and 4 years. Females selected nest‐sites in fallows or cereal fields, in areas of low patch‐type diversity, far from human infrastructure, and with good horizontal visibility. These results suggest that females look for shelter, but also need to have good visibility while incubating, and they support the hypothesis that nest selection is a trade‐off between concealment and visibility. We interpret both preferences as adaptations to reduce predation pressure, one of the main causes of nest failure in this species. Nests were placed on slopes significantly orientated to the southeast, which suggests that females also seek sites protected from the cold north‐westerly winds that are prevalent in the study area. To reduce nest destruction, harvesting should be delayed as long as possible and habitat conservation measures should not be restricted to lek sites but also include nesting areas, which are frequently located far from leks.

Does Nest-Guarding in Female Tuatara (Sphenodon punctatus) Reduce Nest Destruction by Conspecific Females?

Although parental care is generally rare among reptiles, nest-guarding occurs in some species and is usually attributed to defense against nest predation. Nest-guarding also occurs in the Tuatara (Sphenodon punctatus), but nest predation on rodent-free islands does not appear to be a significant threat to nesting success in this species. We studied a population of colonially nesting Tuatara on rodent-free Stephens Island, New Zealand, over four years and tested the hypothesis that female Tuatara guard their nests to defend them from excavation by conspecific females. We located 73 nests for which females could be assigned based on observations during oviposition. Nearly 25% of these nests were subsequently excavated by another female, but only 56% of the nests were guarded by the females that constructed them. We found a trend where guarded nests were less likely to be excavated than unguarded nests. Females were more likely to guard their nests, and guarded nests for longer, as the activity of other females on the date of oviposition increased. Nest-guarding in Tuatara appears to be adaptive in that it tends to reduce the likelihood of nest excavation by other females, but social interactions may affect females' propensity to guard, because guarding behavior was influenced by the activity of conspecifics at the time of oviposition.

Does beekeeping reduce genetic variability in Melipona scutellaris (Apidae, Meliponini)?

Many factors have contributed to reductions in wild populations of stingless bees, such as: deforestation, displacement and destruction of nests by honey gatherers, as well as use of insecticides and other agrochemicals. All of these can potentially affect the populational structure of native species. We analyzed genetic variability and populational structure of Melipona scutellaris, based on five microsatellite loci, using heterologous primers of M. bicolor. Samples were taken from 43 meliponaries distributed among 30 sites of four northeastern states of Brazil (Pernambuco, Alagoas, Sergipe, and Bahia). Thirty-one alleles were found to be well distributed among the populations, with sizes ranging from 85 to 146 bp. In general, there was a variable distribution and frequency of alleles among populations, with either exclusive and/or fixed alleles at some sites. The population of Pernambuco was the most polymorphic, followed by Bahia, Alagoas and Sergipe. The heterozygosity was Ho = 0.36 on average, much lower than what has been reported for M. bicolor (Ho = 0.65). Most populations were not under Hardy-Weinberg equilibrium. We found a higher variation within rather than among populations, indicating no genetic structuring in those bees maintained in meliponaries. This apparent homogenization may be due to intense beekeeping activity, including exchange of genetic material among beekeepers. Based on our findings, we recommend more studies of meliponaries and of wild populations in order to help orient management and conservation of these native pollinators.

Female biased mortality caused by anthropogenic nest loss contributes to population decline and adult sex ratio of a meadow bird

Meadow breeding birds such as the whinchat Saxicola rubetra have been declining due to increased farming intensity. In modern grassland management, the first mowing and the bird’s breeding cycle coincide, causing high nest destruction rates and low productivity of grassland bird populations. However, it is virtually unknown whether the mowing process directly affects adult survival by accidentally killing incubating females. We studied adult survival of an Alpine whinchat population during two breeding seasons using either colour-ringing or radio-tracking of 71 adults. Assessing territories, mowing phenology and nest destruction from 1988 to 2007 allowed changes in the factors associated with female mowing mortality to be estimated. Adult survival over 5-day-periods was Φ = 0.986, but during the period of mowing female survival was strongly reduced ( Φ = 0.946). As a result, 80.6% of the males, but only 68.4% of the females survived the breeding season. Mowing undoubtedly killed two of 20 radio-tagged females when they were laying or incubating. In the 20-year period, an increasing proportion of nests were destroyed before the chicks hatched and this change was associated with an increased distortion of the adult sex ratio. Modelling the population growth rate showed that including the additional effect of mowing on female mortality resulted in a 1.7 times faster local population decline. These results are consistent with the hypothesis that the extinction of whinchat populations in the lowlands of central Europe was caused not only by habitat degradation and low productivity, but also by increased man-made female mortality.

Gull Predation and Breeding Success of Common Eiders on Stratton Island, Maine

Common Eider (Somateria mollissima dresseri) breeding success and gull-eider interactions were studied at Stratton Island, Maine in 2004 and 2005. Eiders suffered little nest predation, and most egg losses to gulls were either facilitated by researcher intrusions or confined to newly initiated, unattended nests. Despite high nest success (>80%) in both study years, predation watches indicated that few, if any, ducklings survived to fledging as a result of extreme harassment and predation by Great Black-backed Gulls (Larus marinus). Gull attacks were opportunistic, involved one to 36 gulls, and often resulted in complete crèche destruction. Herring Gulls (L. argentatus) also took occasional young and eggs. Although Stratton Island is managed as a tern restoration site, and gull control measures to enhance tern productivity include nest destruction and shooting of tern predators, gulls continued to congregate around crèching areas and to prey on ducklings. We suggest that additional gull control measures, particularly at a nearby gull colony, may enhance duckling survival. We also recommend monitoring of other eider colonies in the region to better assess duckling survival and recruitment rates.

PROTECTIVE POTENTIAL OF CERTAIN PESTICIDES TO GRAPES FROM HOUSE SPARROW, PASSER DOMES7ICUS NILOTICUS ATTACK

This study was conducted during the restricted period which started from the middle of June of each of 2006 and 2007 at Belbeis district, Shakia Governorate to investigate the Protective Potential of certain Pesticides to grapes from house sparrow, Passer domesticus ni/oticus attack. Four chemical Pesticides namely, Bayfidan, Pyriban, Cidial L and Captan, were used. Two bird mechanical management means namely, nest destruction and Reflecting stripes were also tested. Results showed that the tested pesticides at 0.5% and 1.0% concentration achieved quite protection for seedless grape against house sparrows compared to check treatment The degree of protection was related to increasing the level of application. The high repellency effect against the house sparrow was occurred by Bayfidan and Captan during second season while the same results were realized by Bayfidan and Pyriban during first season. Also, the gained figures assured that Nest destruction and reflection strips gave a great protection against house sparrow. Reflection strips as bird scaring was preferable than nest destruction in protecting the seedless grape from the birds. The effect of two used concentrations (0.5% and 1.0%) of the four tested pesticides on grape fruits. The whole pesticides induced a considerable increase in rate of changing in weight and in both long (L) and short (S) diameter of berries grape during two seasons. In addition, Cidial L gave the highest rate of changing for each of soluble solids and acidity and the lowest figures was recorded in case of Bayfidan at 1.0% concentration.

Long‐term increase in the fecundity of hen harriers in Wales is explained by reduced human interference and warmer weather

AbstractThe conservation status of the hen harrier Circus cyaneus in Britain, and its pivotal role in the raptor–grouse moor conflict, has rendered research on the factors influencing its population dynamics of crucial importance. Using over 20 years of data, we examine influences on the reproductive output of the small, but recently expanding, population of Welsh hen harriers. Productivity (fledglings per breeding attempt) has steadily increased with time, being the highest in recent years. Available evidence suggested that food availability could not account for these recent increases. Human interference (apparently, largely or entirely in the form of nest destruction by grouse moor gamekeepers) had a large influence on productivity, despite being restricted to a minority of the breeding population. This negative effect, and a positive effect of May temperature, was most influential on variation in breeding productivity. This study quantifies, for the first time, that cessation of persecution can result in a marked improvement in hen harrier reproductive output. Nest predation by red foxes Vulpes vulpes had no effect on variation in breeding productivity and there was no evidence that control of fox numbers by gamekeepers compensated for their depression of productivity through destroying harrier nests. Our analyses also indicated that gamekeepers probably destroyed an unknown number of nests before they were discovered. We argue that a low proportion of territorial females that apparently breed, in cases when clutch size and fledged brood size are high, may be an indication of persecution. The recent increase in the breeding productivity of Welsh harriers has probably been influential in the recent recovery of the Welsh harrier population and has apparently been due to a combination of cessation of human interference and warmer temperatures.

Nosocomial Dermatitis Caused by Dermanyssus gallinae

The mite Dermanyssus gallinae may cause pruritic dermatitis in humans. We describe a case of nosocomial infestation with D. gallinae from an abandoned pigeon nest suspended on the front wall of the Hôpital Henri Mondor near a window. Close surveillance and regular destruction of pigeon nests could prevent these incidents of infection in humans.

Movements and Survival of Molt Migrant Canada Geese From Southern Michigan

ABSTRACT We studied movements and survival of 250 female giant Canada geese (Branta canadensis maxima) marked during incubation with either satellite‐monitored platform transmitting terminals or very high frequency radiotransmitters at 27 capture areas in southern Michigan, USA, in 2000–2003. We destroyed nests of 168 radiomarked females by removing eggs after day 14 of incubation, and we left nests of 82 incubating hens undisturbed after capture and marking. Of females whose nests we experimentally destroyed, 80% subsequently migrated from breeding areas to molt remiges in Canada. Among 82 nests left undisturbed, 37 failed due to natural causes and 51% of those females departed. Migration incidence of birds that nested in urban parks was low (23%) compared with migration incidence of birds that nested in other classes of land use (87%). Departure of females from their breeding areas began during the second and third weeks of May, and most females departed during the last week of May and first week of June. Based on apparent molting locations of 227 marked geese, birds either made long‐distance migratory movements &gt;900 km, between latitudes 51° and 64° N, or they remained on breeding areas. Molting locations for 132 migratory geese indicated 4 primary destinations in Canada: Western Ungava Peninsula and offshore islands, Cape Henrietta Maria, Northeast James Bay and offshore islands, and Belcher Islands, Hudson Bay, Canada. Following molt of remiges, Canada geese began to return to their former nesting areas from 20 August through 3 September, with 37% arriving on or before 15 September and 75% arriving on or before 1 October. Migration routes of geese returning to spring breeding areas were relatively indirect compared with direct routes taken to molting sites. Although overall survival from May through November was 0.81 (95% CI: 0.74–0.88), survival of migratory geese marked on breeding sites where birds could be hunted was low (0.60; 95% CI: 0.42–0.75) compared with high survival of birds that remained resident where hunting was restricted (0.93; 95% CI: 0.84–0.97). Nest destruction can induce molt migration, increase hunting mortality of geese returning from molting areas, and reduce human‐goose conflicts, but managers also should consider potential impacts of increasing numbers of molt migrants on populations of subarctic nesting Canada geese.

Predação de ninhos de Trachemys dorbigni (Duméril &amp; Bibron) (Testudines, Emydidae) no extremo sul do Brasil

Ninhos da tartaruga tigre-d'água, Trachemys dorbigni, foram monitorados durante a estação reprodutiva de 2005/2006 para avaliar as taxas de predação e a variação temporal destas; identificar as espécies predadoras, sua importância na destruição dos ninhos e determinar a influência da dispersão dos ninhos sobre a predação, no extremo sul do Brasil. Dos 58 ninhos monitorados, 98% (n = 57) foram destruídos por predadores. Eventos de predação ocorreram predominantemente nas primeiras 48 horas após a oviposição e não houve variação temporal nas taxas de predação. Através de armadilhas fotográficas e observações diretas foram identificadas seis espécies predadoras dos ninhos, não havendo prevalência de nenhuma das espécies. A densidade de ninhos não influenciou as taxas de predação, mas houve correlação negativa entre densidade e tempo decorrido entre a desova e a predação.