Can chemical cues from a predator change the nest-selection of birds?

2021 ◽  
pp. 175815592110128
Author(s):  
Jong Koo Lee

The nest-selection process of many birds can be affected by traces of potential predators. However, it remains debatable if birds are capable of recognizing and responding to chemical cues of predators when selecting their nest sites. To investigate this, I installed a pair of nest boxes at 12 sites in 2013 and 2014 and 24 sites in 2015 and 2016, each with nest conditions that differed for two variables, that is, height (high or low), hole depth (deep or shallow). Under these experimental conditions, tree swallows displayed a strong preference for high nests over low ones and deep hole nests over shallow holes. In a consecutive experiment, we applied chemical cues (i.e. urine, feces) of domestic cats to the preferred nests to determine if this would alter the nests selected; the chemical cues led to a stepwise alteration in the nests selected. The birds changed their nest selection by chemical cues of a predator when one variable (nest height or hole depth) was applied. Interestingly, however, when provided with a choice between the most preferred nest combination (high and with a deep hole) and the least preferred nest combination (low and with a shallow hole), tree swallows selected the most preferred nest even in the presence of the chemical cues.

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Alexander I. Novichkov ◽  
Anton I. Hanopolskyi ◽  
Xiaoming Miao ◽  
Linda J. W. Shimon ◽  
Yael Diskin-Posner ◽  
...  

AbstractAutocatalytic and oscillatory networks of organic reactions are important for designing life-inspired materials and for better understanding the emergence of life on Earth; however, the diversity of the chemistries of these reactions is limited. In this work, we present the thiol-assisted formation of guanidines, which has a mechanism analogous to that of native chemical ligation. Using this reaction, we designed autocatalytic and oscillatory reaction networks that form substituted guanidines from thiouronium salts. The thiouronium salt-based oscillator show good stability of oscillations within a broad range of experimental conditions. By using nitrile-containing starting materials, we constructed an oscillator where the concentration of a bicyclic derivative of dihydropyrimidine oscillates. Moreover, the mixed thioester and thiouronium salt-based oscillator show unique responsiveness to chemical cues. The reactions developed in this work expand our toolbox for designing out-of-equilibrium chemical systems and link autocatalytic and oscillatory chemistry to the synthesis of guanidinium derivatives and the products of their transformations including analogs of nucleobases.


2021 ◽  
pp. 1-11
Author(s):  
Catherine Chuirazzi ◽  
Melissa Ocampo ◽  
Mizuki K. Takahashi

Abstract Diet quality and predation are two critical factors in determining the growth and development of organisms. Various anurans are susceptible to phenotypic changes influenced by these factors. Yet, few studies examined prey diet quality as potential influence over predator-induced traits. Using wood frog tadpoles (Lithobates sylvaticus) as a model species, we investigated the effects of three diet compositions (plant-based, animal-based, omnivorous) crossed with presence or absence of chemical cues from predatory dragonfly larvae (Aeshnidae). After 35 days, we recorded 11 morphological measurements, Gosner stage, and intestinal length of tadpoles to assess phenotypic changes under the six different experimental conditions. Our results showed the additive effects of both diet quality and predator chemical cue without detection of interactions between the two. Tadpoles receiving the omnivorous diet grew and developed faster with wider denticle rows than those receiving the plant or animal diets. The growth and development of tadpoles receiving only the animal diet were significantly hindered. These results emphasize the importance of diet quality in the growth and development of larval wood frogs. Chemical cues from predators significantly reduced tadpole body size but, in contrast to previous findings, did not affect tail size. Our experimental procedure of providing water containing predator and injured conspecific chemical cues on a weekly basis likely provided relatively weak predation risk perceived by tadpoles compared to previous studies using caged predators. The predator environment in our experiment, however, represents one ecologically relevant scenario in which predation risk is not urgent.


1979 ◽  
Vol 57 (10) ◽  
pp. 2072-2078 ◽  
Author(s):  
Reid N. Harris

The relationship between territorial aggression and reproductive success was studied on a well-established, insular population of tree swallows. Four treatments of nest boxes that differed in interbox distances were created. Short interbox distances significantly reduced the occupancy of nest boxes both between and within years. Swallows in short interbox distance treatments defended more than one nest box, which was an additional resource not necessary for their successful reproduction. Excluded potential breeders attempted to colonize vacant boxes within another swallow's territory throughout the nestling period, but were usually prevented by the aggression of the resident pair. Aggressive activity had no direct effect on three measures of a swallow's reproductive output: percent young fledged, nestling growth, and fledgling weights. The concept of intraspecific aggressive neglect is questioned. However, by excluding potential breeders from nesting, for whatever reason, breeding tree swallows increased their relative genetic contribution to future generations.


1996 ◽  
Vol 74 (10) ◽  
pp. 1819-1825 ◽  
Author(s):  
Wallace B. Rendell ◽  
Nicolaas A. M. Verbeek

Researchers may reduce the numbers of haematophagous ectoparasites in nest boxes of cavity-nesting birds by removing old nests from boxes and, as a result, eliminate an important selective pressure that could influence the results from nest-box studies of birds. We recorded the numbers of parasites in tree swallow (Tachycineta bicolor) boxes in which we manipulated the presence, amount, and quality of old nests. Bird fleas (Ceratophyllus idius) were more numerous in boxes with old nests, and there was a positive correlation between nest volume and flea numbers. In one year, there was a positive association between fowl mite (Ornithonyssus sylviarum) numbers and nest volume; otherwise, fowl mites and blow flies (Protocalliphora sialia) were equally numerous in all nest types. We conclude that ectoparasites whose over-winter survival depends on old nests are more numerous in boxes with old nests, whereas parasites whose over-winter survival is independent of old nests infect nest sites randomly. Also, reinfection and nest microclimate likely contributed to variance in parasite numbers between nest types and years, respectively. We recommend caution when speculating about the possible effects of cleaning boxes on parasites that occur in nests because different species of parasites are not influenced similarly by old nests.


PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9211
Author(s):  
Johanne M. Martens ◽  
Helena S. Stokes ◽  
Mathew L. Berg ◽  
Ken Walder ◽  
Shane R. Raidal ◽  
...  

Indirect transmission of pathogens can pose major risks to wildlife, yet the presence and persistence of wildlife pathogens in the environment has been little studied. Beak and feather disease virus (BFDV) is of global conservation concern: it can infect all members of the Psittaciformes, one of the most threatened bird orders, with infection often being lethal. Indirect transmission of BFDV through contaminated nest hollows has been proposed as a major infection source. However, data on whether and for how long nest sites in the wild remain contaminated have been absent. We determined the BFDV status of birds (parents and nestlings) for 82 nests of Crimson Rosellas, Platycercus elegans and Eastern Rosellas, Platycercus eximius. In 11 of these nests (13.4%, 95% confidence interval 6.9–22.7), we found an infected parent or nestling. Using nest swabs, we then compared BFDV presence at three points in time (before, during and after breeding) in three groups of nest boxes. These were nest boxes occupied by infected birds, and two control groups (nest boxes occupied by uninfected birds, and unoccupied nest boxes). Detection of BFDV on nest swabs was strongly associated with the infection status of parents in each nest box and with the timing of breeding. During breeding, boxes occupied by BFDV-positive birds were significantly more likely to have BFDV-positive nest swabs than boxes occupied by BFDV-negative birds; nest swabs tested BFDV-positive in 80% (28.4–99.5) of nests with parental antigen excretion, 66.7% (9.4–99.2) of nests occupied by parents with BFDV-positive cloacal swabs and 66.7% (22.3–95.7) of nests occupied by parents with BFDV–positive blood. 0% (0–52.2) of nests with BFDV–positive nestlings had BFDV–positive nest swabs. Across all boxes occupied by BFDV-positive birds (parents or nestlings), no nest swabs were BFDV–positive before breeding, 36.4% (95% CI 10.9–69.2) were positive during breeding and 9.1% (0.2–41.3) remained positive after breeding. BFDV was present on nest swabs for up to 3.7 months. Our study provides novel insights into the potential role of nest cavities and other fomites in indirect transmission of BFDV, and possibly other pathogens, and offers a non-invasive method for surveillance of pathogens in wild bird populations.


2001 ◽  
Vol 11 (4) ◽  
pp. 287-300 ◽  
Author(s):  
Luís Fábio Silveira ◽  
Wolf Dieter Bartmann

Brazilian Merganser Mergus octosetaceus is considered to be one of the rarest and most threatened species in the Neotropical region, yet little is known about its distribution and life-history. We studied the population of Brazilian Merganser in and around Serra da Canastra National Park (SCNP) in Minas Gerais, Brazil, during 1996, with additional observations from 1997 to 2000. In this paper we report the sighting of previously undiscovered pairs and present some new behavioural data, including a description of calls performed by males and females, feeding behaviour, home ranges, parental care and population density. We also describe a previously unreported plumage of the young. A total of 39 individuals were recorded, comprising 12 adults (six pairs) and 27 young. Brood size ranged from two to four (mean 2.7), being smaller than in other Mergus spp. (e.g. Goosander Mergus merganser). Two pairs were located within the SCNP, and four on unprotected stretches of river outside. Home range was large compared with other Mergus spp., each pair using on average 9 km of river. Range size was thought to be related to the availability of suitable nesting and feeding sites. SCNP and its environs contain very little mature gallery forest with trees large enough to provide nest sites (most having been selectively logged in the past). There is also competition for nest sites with other birds and mammals. All suitable habitat surrounding the SCNP is now occupied by adult birds, leaving none for young birds. Further research is needed to determine the fate and dispersion routes of juveniles. Future conservation priorities for Brazilian Merganser in and around SCNP include the installation of nest boxes to test whether the availability of good quality nest sites limits breeding success. A captive breeding programme could be established using eggs from these nest boxes. This would help to ensure the survival of this species and to provide birds for future reintroduction programmes should they be deemed necessary. Further surveys, with subsequent establishment of reserves at key sites, are required throughout the Brazilian Merganser's range.


2012 ◽  
Vol 36 (1) ◽  
pp. 18-29 ◽  
Author(s):  
Andrzej Węgrzynowicz

Abstract The occupation of nest-boxes by House- and Tree Sparrow in Warsaw was investigated in 2005-2009 and in 2012. Riparian forests, younger and older parks in downtown, and housing estates were included in the study as 4 types of habitats corresponding to the urbanization gradient of Warsaw. 1035 inspections of nest-boxes suitable for both species (type A) were carried out during the breeding period and 345 nest-boxes of other types were inspected after the breeding period. In order to determine the importance of nest-boxes for both species on different plots, obtained data were analyzed using Nest-box Importance Coefficient (NIC). This coefficient describes species-specific rate of occupation of nest-boxes as well as the contribution of the pairs nesting in them. Tree Sparrow occupied a total of 33% of A-type nest-boxes, its densities were positively correlated with the number of nest-boxes, and seasonal differences in occupation rate were low for this species. The NIC and the rate of nest-box occupation for Tree Sparrow decreased along an urbanization gradient. House Sparrow used nest-boxes very rarely, only in older parks and some housing estates. Total rate of nest-box occupation for House Sparrow in studied plots was 4%, and NIC was relatively low. However, locally, installation of nest-boxes limited House Sparrow decline caused by reduced availability of its typical nest sites. Both species used only A-type nest boxes. The rate of nest-box occupation by House Sparrow decreased sharply since 1980s, and opposite trend was observed for Tree Sparrow. These alterations are consistent with the general changes in both species populations in Warsaw in recent decades: decrease in House Sparrow and increase in Tree Sparrow number. The presented results suggest that loss of nest sites may not be the main reason of decrease in House Sparrow population in Warsaw. Additionally, House Sparrow decline leads to increase in nest sites (including nest-boxes) available for Tree Sparrow, what may contribute to the expansion of the latter species.


1996 ◽  
Vol 74 (6) ◽  
pp. 1084-1091 ◽  
Author(s):  
Andrew G. Horn

I describe the dawn songs of 38 male tree swallows (Tachycineta bicolor) recorded at five sites near Wolfville, Nova Scotia. Males deliver dawn song each morning during the hour before dawn, while flying elliptical paths above their nest sites. These dawn songs consist of syllables approximately 0.15 s long, delivered every 1.5 s. Each male has a recorded repertoire of one to seven discrete syllable types (average 2.6) and may repeat each syllable type an apparently random number of times before switching to the next. Most syllables could be classified on the basis of their structure into seven types, with much variation among renditions by different males of any given syllable type. Three of these syllable types were very similar to call notes that have specific uses at other times of day. Syllable types were randomly distributed among males and sites. In this species neither syllable type, the number of times each type is repeated (string length), nor the number of types a male sings (repertoire size) appears to carry particular messages or advertise male quality. Instead, syllable types may provide individual distinctiveness and variety in song sequences.


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