Principal Nest Research Articles

Interactive effects of habitat attributes and predator identity explain avian nest predation patterns

ABSTRACT Predation is the main cause of nest failure among birds. Habitat characteristics play a critical role in affecting nest predation by modifying nest conspicuousness and ease of access to predators. Here, using artificial nests containing a canary egg and a model clay egg we examined and compared nest predation rates and the principal nest predators in three different Patagonian forest stand types. Also, we evaluated how vegetation cover and nest height affected the different nest predators. We found lower nest predation rates in evergreen than deciduous forests, suggesting the forest type as a key factor modulating the risk of nest predation. We identified birds, an arboreal marsupial (Dromiciops gliroides), and mice as the main nest predators in the study area. These nest predators responded differently to the microhabitat conditions around the nest. Predation by birds was mainly related to nests placed closer to the ground, while marsupial nest predation was linked to greater shrub cover and mice showed no response to microhabitat conditions. Together, our results suggest that predation rates result from the interplay between large and small scale habitat characteristics, in addition to predator assemblages. Comparing specific predator-prey interactions is key for understanding the underlying mechanisms influencing nest predation.

On the Combinatorics of Fibonacci-Like Non-renormalizable Maps

In this paper, we extend Fibonacci unimodal map to a wider class. We describe the combinatorial property of these maps by first return map and principal nest. We give the sufficient and necessary condition for the existence of this class of maps. Moreover, for maps with ’bounded combinatorics’, we prove that they have no absolutely continuous invariant probability measure when the critical order $$\ell $$ is sufficiently large; for maps with reluctantly recurrent critical point, we prove they have absolutely continuous invariant probability measure whenever the critical order $$\ell >1$$ .

Snakes are the principal nest predators of the threatened reed parrotbill in a coastal wetland of eastern China

Nest predation is a major limiting factor of bird reproductive success, and predation by snakes may have particularly adverse effects on passerines. The reed parrotbill (Paradoxornis heudei) is a threatened passerine that inhabits reedbeds in East China, where it faces the risk of population decline due to habitat loss and degradation. Studies on the nest predation of this species are lacking. In this study, we monitored reed parrotbill nests in the core area of the Yancheng Nature Reserve, Jiangsu Province, China. We tracked the final fate of each nest and determined the identity of the predators using infrared cameras. We monitored a total of 13 and 15 active nests in 2017 and 2019, respectively, but only 5 nests were successful. Nest predation was responsible for 22 of 23 nest failures (95.7%). Snakes were the principal predators of the nests, responsible for 19 predation events (86.4%). We used abandoned reed parrotbill nests and quail eggs to create artificial nests. However, the survival rate of the artificial nests (63.3%) was significantly higher than that of the natural nests (11.3%), and rats replaced snakes as the principal predators. The best model indicated that the daily survival rate of reed parrotbill nests decreased with nest age. Our findings suggest that severe snake predation may be an important factor threatening populations of the reed parrotbill, even though the wetland habitat is well protected. The identification of specific nest predators may facilitate the conservation of this near-threatened bird through the development of effective management strategies in reserves. More studies on population estimates of the reed parrotbill and the interactions between this endangered bird and snakes using natural (rather than artificial) nests in different areas are needed.

Variation in age-dependent nest predation between island and continental Rufous Fantail (Rhipidura rufifrons) subspecies

ABSTRACT Comparative studies of nest predation and identification of nest predators promote understanding of the selective environment that shapes avian life histories. Due to the low diversity of native mammalian and reptilian predators on oceanic islands, insular forest birds are assumed to incur lower nest predation rates than related continental species. We studied correlates of nest predation in insular and continental subspecies of Rufous Fantail (Rhipidura rufifrons) found on the island of Rota and in eastern Australia. Overall, daily survival rate (DSR) was similar between study sites, but egg stage DSR (laying and incubation) was higher in Australia than on Rota while nestling stage DSR was higher on Rota than in Australia. DSR was negatively related to nest age in Australia and the magnitude of this relationship varied by year. On Rota, DSR was higher in the nestling stage than during the egg stage and also higher on our study plot where Mariana Crows (Corvus kubaryi)—the principal nest predator...

Personality and density affect nest defence and nest survival in the great tit

Recent studies suggest that individual variation in behaviour of prey individuals may cause distinctive responses to nest predators and cooperation with conspecifics. We assessed individual differences during a novel object test and whether these responses were related to nest failure and survival of females during incubation. We additionally carried out experimental trials in natural field conditions using a stuffed pine marten, a principal nest predator, to test for a relationship between neophobia and mobbing predators. Our results show that antipredator responses of breeding great tits are dependent on their personality and personality type of neighbouring conspecifics. We found that neophilic individuals (those that rapidly resumed feeding of nestlings in the presence of a novel object) have an advantage over neophobic individuals (those that slowly resumed feeding of nestlings in the presence of a novel object) in their reproductive success, as measured in numbers of successful nests and of females that survived. Furthermore, neophilic-neophilic pairs exhibited stronger antipredator mobbing responses than neophobic-neophobic pairs. Results show that consistent individual differences in response against novel objects and antipredator behaviour are related, and that these responses are important predictors of nest failure in breeding great tits.

Parapuzzle of the multibrot set and typical dynamics of unimodal maps

We study the parameter space of unicritical polynomials f_c : z ↦ z^d + c . For complex parameters, we prove that for Lebesgue almost every c , the map f_c is either hyperbolic or infinitely renormalizable. For real parameters, we prove that for Lebesgue almost every c , the map f_c is either hyperbolic, or Collet–Eckmann, or infinitely renormalizable. These results are based on controlling the spacing between consecutive elements in the “principal nest” of parapuzzle pieces.

Nest Predators of Ground-nesting Birds in Montane Forest of the Santa Catalina Mountains, Arizona

Abstract We used time-lapse video cameras and track plates to identify nest predators of Red-faced Warblers (Cardellina rubrifrons) and Yellow-eyed Juncos (Junco phaeonotus) in high-elevation (> 2,300 m) forests of the Santa Catalina Mountains in southeastern Arizona. Mammals, especially gray fox (Urocyon cinereoargenteus) and cliff chipmunk (Tamias dorsalis), were the principal nest predators of Red-faced Warblers and Yellow-eyed Juncos within our study system, accounting for 89% of all nest depredations. Our study is one of the first to use video cameras at real nests to document the prevalence of nest predators in montane forest ecosystems. Additional research is needed to learn if mammals are the dominant nest predators in other montane environments.

Local connectivity of Julia sets for unicritical polynomials

We prove that the Julia set J(f) of at most finitely renormalizable unicritical polynomial f: ℤ → z d + c with all periodic points repelling is locally connected. (For d = 2 it was proved by Yoccoz around 1990.) It follows from a priori bounds in a modified Principal Nest of puzzle pieces. The proof of a priori bounds makes use of new analytic tools developed in [KL09] that give control of moduli of annuli under maps of high degree.

Return times of polynomials as meta-Fibonacci numbers

We consider generalized closest return times of a complex polynomial of degree at least two. Most previous studies on this subject have focused on the properties of polynomials with particular return times, especially the Fibonacci numbers. We study the general form of these closest return times. The main result of this paper is that these closest return times are meta-Fibonacci numbers. In particular, this result applies to the return times of a principal nest of a polynomial. Furthermore, we show that an analogous result holds in a tree with dynamics that is associated with a polynomial.

Predators of Spotted Flycatcher Muscicapa striata nests in southern England as determined by digital nest-cameras

Capsule Avian predators are principally responsible. Aims To document the fate of Spotted Flycatcher nests and to identify the species responsible for nest predation. Methods During 2005–06, purpose-built, remote, digital nest-cameras were deployed at 65 out of 141 Spotted Flycatcher nests monitored in two study areas, one in south Devon and the second on the border of Bedfordshire and Cambridgeshire. Results Of the 141 nests monitored, 90 were successful (non-camera nests, 49 out of 76 successful, camera nests, 41 out of 65). Fate was determined for 63 of the 65 nests monitored by camera, with 20 predation events documented, all of which occurred during daylight hours. Avian predators carried out 17 of the 20 predations, with the principal nest predator identified as Eurasian Jay Garrulus glandarius. The only mammal recorded predating nests was the Domestic Cat Felis catus, the study therefore providing no evidence that Grey Squirrels Sciurus carolinensis are an important predator of Spotted Flycatcher nests. There was no evidence of differences in nest survival rates at nests with and without cameras. Nest remains following predation events gave little clue as to the identity of the predator species responsible. Conclusions Nest-cameras can be useful tools in the identification of nest predators, and may be deployed with no subsequent effect on nest survival. The majority of predation of Spotted Flycatcher nests in this study was by avian predators, principally the Jay. There was little evidence of predation by mammalian predators. Identification of specific nest predators enhances studies of breeding productivity and predation risk.

Quadratic polynomials and combinatorics of the principal nest

We supplement the definition of principal nest, introduced by M. Lyubich, with a system of frames that makes possible the classification of combinatorial types for every level of the nest. As a consequence, we give necessary and sufficient conditions for the admissibility of a type and prove that given a sequence of finite admissible types, there is a quadratic polynomial whose nest realizes the sequence.

Invariant Measures Exist Without a Growth Condition

Given a non-flat S-unimodal interval map f, we show that there exists C which only depends on the order of the critical point c such that if |Df n (f(c))|≥C for all n sufficiently large, then f admits an absolutely continuous invariant probability measure (acip). As part of the proof we show that if the quotients of successive intervals of the principal nest of f are sufficiently small, then f admits an acip. As a special case, any S-unimodal map with critical order ℓ<2+ɛ having no central returns possesses an acip. These results imply that the summability assumptions in the theorems of Nowicki & van Strien [21] and Martens & Nowicki [17] can be weakened considerably.

BREEDING SYNCHRONY AND NEST PREDATION IN RED-WINGED BLACKBIRDS

Three previous studies have disagreed on whether breeding synchrony increases nest success through reduced nest predation in Red-winged Blackbirds (Agelaius phoeniceus) in eastern North America. We used data from an 11-yr study of redwings in eastern Ontario, Canada, to duplicate the analyses of the one study (by D. F. Westneat) that did show that nesting synchrony reduced predation. We found no evidence that nest predation and nest success were affected by nesting synchrony. We did find significant effects of female age, clutch size, and clutch initiation date on nest success, but overall, our independent variables explained very little variation in nest success. We hypothesize that the difference between our results and Westneat's may be attributable to differences in the principal nest predators. Mammals appeared to be important nest predators in our study, as is typical for eastern populations of Red-winged Blackbirds. Mammals appeared to be less important nest predators in Westneat's study, probably because that study area was fenced and the grass between ponds was mowed. Red-winged Blackbirds mob avian predators, but have limited ability to defend nests from mammals. Group mobbing of avian predators could result in a positive relationship between nesting synchrony and nest success when birds are the most important nest predators. The greater importance of avian nest predators in western than in eastern populations of Red-winged Blackbirds could account for some differences in social polygyny between those populations. However, our results indicate that nesting decisions by female redwings in eastern populations should not be affected by the nesting activity of other females. Thus, social polygyny in this population does not arise through an advantage of group living.

Summer Nesting of Turtles in Alligator Nests in Florida

We examined summer use of American alligator (Alligator mississippiensis) nests by nesting turtles, principally Florida redbelly turtles (Pseudemys nelsoni), in lakes Okeechobee, Apopka, Griffin, and Jesup during 1986-1991 and in three other wetlands in peninsular Florida for >3 yr. Other turtle species recorded using alligator nests were Apalone ferox, Kinosternon sp, and Sternotherus odoratus. In the seven wetlands, 26.6% of 1586 occupied (i.e, active) alligator nests contained R nelsoni eggs. Of the four lakes sampled for 6 yr, Lake Okeechobee had the highest incidence of use of occupied nests by nesting P nelsoni and the most turtle clutches per occupied nest. Nesting P nelsoni used occupied nests more frequently in Lake Apopka than in Lake Jesup Nesting P nelsoni used vacant alligator nests (63.6%) more often than occupied nests (36.1%) at Lake Okeechobee, which suggests that attending female alligators may deter nesting turtles. Annual incidence of nest use by nesting turtles was correlated positively with June-July mean water levels in lakes Okeechobee and Jesup, where emergent marsh was the principal habitat and alternative nest sites were probably limited during high-water conditions. In the four lakes combined, turtles did not preferentially select alligator nests in a particular habitat type. Use of 1330 occupied nests by turtles in the four lakes was significantly lower in 1990 (13.5%) than in other years (21.9%/6-29.3%). We hypothesize that observed differences among lakes in turtle use of alligator nests resulted from differences in (1) water- level fluctuations, (2) availability of alternative nesting sites (i.e, distance to upland habitat), and (3) turtle population sizes.

Conformal measures and Hausdorff dimension for infinitely renormalizable quadratic polynomials

We show in this paper that iff is a quadratic infinitely many times renormalizable polynomial of sufficient high combinatorial type, then: HD (J(f))= inf{δ:∃ δ-conformal measure for f} We use Lyubich's construction of the principal nest ([Lyu97]) in order to prove this result.

NEST PREDATION AND AVIAN SPECIES DIVERSITY IN NORTHWESTERN FOREST UNDERSTORY

Empirical evidence to assess the hypothesis that nest predation pressure influences avian assemblage composition is mostly lacking. We examined distribution of predation risk for artificial bird nests in the understory of coniferous and deciduous forests in southeastern Alaska and adjacent western Canada to determine whether habitat-specific nest predation pressure could be a factor influencing habitat selection and, in turn, breeding bird diversity. Two sizes of open-cup nests were constructed of natural materials and placed in nest sites representative of those used by local breeding bird species although, on average, artificial nests were more conspicuous than natural nests monitored in a companion study. Artificial nests were exposed to predation during early and late nesting seasons in 1993 and 1994. Principal nest predators identified using automated cameras were red squirrel (Tamiasciurus hudsonicus), Steller’s Jay (Cyanocitta stelleri; Alaska only), Gray Jay (Perisoreus canadensis; Canada only), a...

Nest re-use and communal nesting inMicrothurge corumbae (Hymenoptera, Megachilidae), with special reference to nest defense

Observations on the nesting activities ofMicrothurge corumbae, carried out at the University Campus of Ribeirao Preto, Sao Paulo, Brazil, from 1977 to 1981, indicated that 61.9 % of nests were re-used by succeeding generations. Re-use by one generation was more frequent than by two generations, and re-use by a third was observed only once. Nests were re-used by one or several females. Single females were more frequently in the first re-use. In these cases nest re-use did not differ essentially from the solitary foundation of a new nest, except for the adoption of a pre-existing nest without excavation. In multifemale nests, analysis of relative age (wing wear), ovarian and spermathecal conditions of associated females and the content of nests at excavation indicated that the social pattern in such colonies is communal. There is some evidence that the associated females are relatives. The chalcidoid waspLeucospis was the principal nest parasite, and ants of the genusCrematogaster were nest predators. In multifemale nests, the rate of parasitism was significantly lower than in solitary nests, indicating that nest-sharing resulted in improved nest defense. On the other hand, the absence of predation on immatures of the first generation of M.commbae in multifemale nests suggests that such nests are also more resistant to attack by predators.

Nesting Ecology and Microhabitat of the Eastern Phoebe in the Central Appalachians

-In 1984, a study of the eastern phoebe (Sayornis phoebe) was conducted on the Appalachian Plateau in western Maryland, principally in the Savage River State Forest. Fledging success and mortality patterns were used as indicators of differences in quality of nest-site microhabitats. A total of 229 fledglings resulted from 84 nesting attempts, an average of 2.73 fledglings per attempt. Fledging success was 61.4%, with early nests generally more successful than late nests. Fledging success was similar among nesting structures, with adherent nests having higher success than statant nests, except on rock outcrops. However, late-adherent nests on rock outcrops did have higher fledging success than late-statant nests. The success of new-active and old-active nests was the same. Losses attributed to predators amounted to 70.1% of all losses. Losses attributed to small predators (55.6%) were significantly higher than that from large predators (14.6%). Other losses were attributed to nests falling (13.9%), human disturbance (5.6%), hatching failure (4.2%), adult death/desertion (3.5%) and inclement weather (2.8%). Losses ascribed to small predators increased from early to late nesting attempts on all nesting structures, but less so for adherent nests on rock outcrops. The principal nest predator was probably the eastern chipmunk (Tamias striatus). Stepwise discriminant function analysis was used to distinguish between microhabitats of high-success (>60%) and low-success (?60%) phoebe nests. Evergreen canopy cover (%), height to nest rim and distance to nearest understory tree were greater at high-success nests; while angle of recess in which the nest was built was smaller. Microhabitat variables with no differences among nesting structures, and therefore probably important in overall nestsite selection, included height of rock outcrop or other structure at the nest location, height to nest rim, width of shelf used for support of nest, length of overhanging structure above nest, height to underhanging structure below nest, height of understory trees and percent evergreen canopy cover. Variables associated with access to the nest tended to affect success more than others.

Effects of Forest Fragmentation on Depredation of Artificial Nests

Depredation on artificial ground and arboreal (1.5 m above ground) nests was studied in mature (uncut) forest stands on a ruffed grouse (Bonasa umbellus) management area in central Pennsylvania from May to August 1986. Predation was evaluated in mature stands with zero, 25, and 50% zones of the surrounding forest fragmented by clearcutting. Nest depredation was highest in the 50% zone and least in the zero percent zone; more arboreal nests than ground nests were disturbed. American crows (Corvus brachyrhynchos) were major predators on nests in the 50% zone, and crows and blue jays (Cyanocitta cristata) caused most nest disturbances in the 25% zone. Our results suggest that fragmentation of surrounding mature forest stands may negatively impact avian nesting success, especially when the principal nest predators are corvids. Predation in fragmented forests may have a greater effect on nesting success of birds nesting above ground than on those nesting at ground level. J. WILDL. MANAGE. 52(1):158-161 Forest fragmentation, or the cutting of remaining natural forest into progressively smaller patches (Harris 1980), negatively impacts abundance and distribution of insectivorous passerines in the eastern United States (Whitcomb et al. 1981). Because forest fragmentation results in greater edge (Ranney et al. 1981) and predators select edges for foraging (Gates and Gysel 1978, Chasko and Gates 1982), predation on avian nests could increase with extensive forest fragmentation (Noss 1983). However, with the exception of a study dealing with predation on artificial nests in woodlots of various sizes (Wilcove 1985), the influence of forest fragmentation on nest predation is not well documented. Clearcutting forest to improve ruffed grouse habitat at the Barrens Grouse Habitat Management Study Area (BGMA) in central Pennsylvania provides suitable nesting habitat for a variety of avian species that nest ?2 m from the ground (Yahner 1986b, Yahner and Cypher 1987). The BGMA contains a sector with no forest fragmentation (zero clearcutting) and sectors with 2 intensities of forest fragmentation (25 and 50% clearcutting) that provided an opportunity to examine the relationship between nest depredation and forest fragmentation. Our objective was to compare depredation on artificial ground and arboreal nests placed in mature forest stands surrounded by uncut forest and 2 intensities of forest fragmentation at the BGMA. We thank R. A. Voytko and R. W. Bond for field assistance. Funding for this study was provided by the Max McGraw Wildlife Foundation and the Pennsylvania Agricultural Experiment Station. W. A. Creed, R. G. Eckstein, and M. J. Lacki reviewed the manuscript. This is Journal Series Paper 7565 of the Agricultural Experiment Station, The Pennsylvania State University, University Park.

Reproductive Success and Nest Predation in the Superb Lyrebird, Menura superba

Breeding success and nest predation were analysed in two superb lyrebird populations studied over six years. Egg success was estimated at 11-20%, giving an annual recruitment rate of 0.1-0.2 fledglings per breeding female. Predation accounted for at least 79% of nesting mortality and the risk was greater during the nestling phase. Preferred nest sites were 0.6-1.8 m above ground level on earth banks and in trees but were most susceptible to predation. Circumstantial evidence implicated native birds and introduced mammals as the principal nest predators. The generality and evolutionary implications of these findings are discussed.