An inexpensive photographic technique for identifying nest predators at active nests of birds.

1994 ◽  
Vol 21 (6) ◽  
pp. 657 ◽  
Author(s):  
RE Major ◽  
G Gowing
Keyword(s):  
High Frequency ◽  
Nest Predation ◽  
Population Decline ◽  
Bird Species ◽  
Reed Switch ◽  
Environmental Modification ◽  
Photographic Technique ◽  
Nest Predators

Change in rate of nest predation due to environmental modification is considered a major cause of population decline of many bird species. Our ability to adequately understand and effectively manage this effect is limited by our ability to identify the relative roles of individual nest predators. This is because nest predation is seldom witnessed despite its high frequency. We describe and evaluate an inexpensive photographic technique for identifying nest predators at active nests. Each camera unit (A$220) was triggered by circuitry (A$30), using a magnetic reed switch attached to a supplementary egg. A total of 51 nests of New Holland honeyeaters (Phylidonyris novaehollandiae) was monitored with the equipment. Of these, 39 were preyed upon. Predation was never witnessed, but predators were captured on film for 72% of nests at which predation occurred.

scholarly journals Investigating how different classes of nest predators respond to the playback of the begging calls of nestling birds

2021 ◽  
Author(s):  
Shilong Liu ◽  
Qiao Xie ◽  
Aiwu Jiang ◽  
Eben Goodale
Keyword(s):  
Small Mammals ◽  
High Frequency ◽  
Nest Predation ◽  
Traffic Noise ◽  
Control Treatment ◽  
Costs And Benefits ◽  
Artificial Nests ◽  
Frequency Components ◽  
Benefits And Costs ◽  
Nest Predators

Abstract Background Begging brings benefits and costs for nestling birds: it can indicate their needs to their parents, but it can also be a cue used by predators to find the nest. The costs, like many variables related to nest predation, can be specific to what kinds of predators are present and their auditory capabilities. These costs and benefits could also be affected by human noise, as noise could disrupt communication to parents and eavesdropping by predators, although human-produced noise might be easily ignored if predators can hear high-frequency components of the begging. We studied nest predation on a generalist bird, the Red-whiskered Bulbul Pycnonotus jocosus, in a tropical rainforest in which there are many kinds of nest predators, including birds, mammals and reptiles. Results In a total of 160 artificial nests, we broadcast recordings of begging nestlings, with and without traffic noise, at two volume levels. We hypothesized that playback would increase predation relative to a silent control, and that mixing in traffic noise with the begging would decrease predation, as the begging signal was masked. However, we hypothesized that some predators, particularly small mammals with sensitive high-frequency hearing, might ignore the traffic noise. We found that predation was lowest for the control treatment, and lower for treatments mixed with traffic noise than for those without it. Small mammals, however, showed an unexpected pattern, strongly avoiding the treatments with traffic noise. Conclusion Our results demonstrate the human-associated noise can disturb nest predators and influence which kinds of predators use begging to locate nests.

Elevated nest predation risk promotes offspring size variation in birds with prolonged parental care.

2019 ◽  
Author(s):  
Gretchen F. Wagner ◽  
Emeline Mourocq ◽  
Michael Griesser
Keyword(s):  
Predation Risk ◽  
Reproductive Cycle ◽  
Perceived Risk ◽  
Nest Predation ◽  
Bird Species ◽  
Size Variation ◽  
Egg Laying ◽  
Offspring Size ◽  
Natural Predation ◽  
Risk Spreading

Predation of offspring is the main cause of reproductive failure in many species, and the mere fear of offspring predation shapes reproductive strategies. Yet, natural predation risk is ubiquitously variable and can be unpredictable. Consequently, the perceived prospect of predation early in a reproductive cycle may not reflect the actual risk to ensuing offspring. An increased variance in investment across offspring has been linked to breeding in unpredictable environments in several taxa, but has so far been overlooked as a maternal response to temporal variation in predation risk. Here, we experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species. Species with prolonged parent-offspring associations increased their intra-brood variation in egg, and subsequently offspring, size. High risk to offspring early in a reproductive cycle can favour a risk-spreading strategy particularly in species with the greatest opportunity to even out offspring quality after fledging.

scholarly journals The dynamics underlying avian extinction trajectories forecast a wave of extinctions

2019 ◽  
Vol 15 (12) ◽  
pp. 20190633 ◽  
Author(s):  
Melanie J. Monroe ◽  
Stuart H. M. Butchart ◽  
Arne O. Mooers ◽  
Folmer Bokma
Keyword(s):  
Extinction Risk ◽  
Population Decline ◽  
Bird Species ◽  
Iucn Red List ◽  
Red List ◽  
Extinction Rate ◽  
Critically Endangered Species ◽  
Extinction Rates ◽  
Historical Times ◽  
Risk Categories

Population decline is a process, yet estimates of current extinction rates often consider just the final step of that process by counting numbers of species lost in historical times. This neglects the increased extinction risk that affects a large proportion of species, and consequently underestimates the effective extinction rate. Here, we model observed trajectories through IUCN Red List extinction risk categories for all bird species globally over 28 years, and estimate an overall effective extinction rate of 2.17 × 10 −4 /species/year. This is six times higher than the rate of outright extinction since 1500, as a consequence of the large number of species whose status is deteriorating. We very conservatively estimate that global conservation efforts have reduced the effective extinction rate by 40%, but mostly through preventing critically endangered species from going extinct rather than by preventing species at low risk from moving into higher-risk categories. Our findings suggest that extinction risk in birds is accumulating much more than previously appreciated, but would be even greater without conservation efforts.

scholarly journals Testing camera traps as a potential tool for detecting nest predation of birds in a tropical rainforest environment

2018 ◽  
Vol 35 ◽  
pp. 1-8 ◽  
Author(s):  
Laís Ribeiro-Silva ◽  
Daniel Fernandes Perrella ◽  
Carlos Biagolini-Jr ◽  
Paulo Zima ◽  
Augusto J. Piratelli ◽  
...  
Keyword(s):  
Nest Predation ◽  
Tropical Rainforest ◽  
Size Range ◽  
Bird Species ◽  
Camera Trap ◽  
Camera Traps ◽  
Predator Species ◽  
Set Up ◽  
Monitoring Devices ◽  
Potential Tool

Identification of the predators of bird nests is essential to test ecological and evolutionary hypotheses and to make practical management decisions. A variety of nest monitoring devices have been proposed but many remain difficult to set up in the field. The aim of this study was to test camera traps as a potential tool to study predation of natural nests in a tropical rainforest environment. Specifically, we registered the predators, assessed their size range, and we compared the use of one and two cameras per nest. Of 122 nests from 24 bird species, 45 (37%) were depredated, and the cameras recorded the predator species in 29 of the total of depredated nests (64%). We identified predators in eight of 16 depredated nests (50%) in which we used one camera trap per nest, and we identified predators in 21 of 29 depredated nests (72%) when we used two camera traps per nest. The predators included six species of birds and six species of mammals, with body masses varying from 20 g to 16.5 kg. Causes for 10 of the 16 detection failures were identified and are discussed. These results suggest that camera traps are viable tools to investigate nest predation in a tropical rainforest area.

scholarly journals Testing camera traps as a potential tool for detecting nest predation of birds in a tropical rainforest environment

2018 ◽  
Vol 35 ◽  
pp. 1-8
Author(s):  
Laís Ribeiro-Silva ◽  
Daniel Fernandes Perrella ◽  
Carlos Biagolini-Jr ◽  
Paulo Zima ◽  
Augusto J. Piratelli ◽  
...  
Keyword(s):  
Nest Predation ◽  
Tropical Rainforest ◽  
Size Range ◽  
Bird Species ◽  
Camera Trap ◽  
Camera Traps ◽  
Predator Species ◽  
Set Up ◽  
Monitoring Devices ◽  
Potential Tool

Identification of the predators of bird nests is essential to test ecological and evolutionary hypotheses and to make practical management decisions. A variety of nest monitoring devices have been proposed but many remain difficult to set up in the field. The aim of this study was to test camera traps as a potential tool to study predation of natural nests in a tropical rainforest environment. Specifically, we registered the predators, assessed their size range, and we compared the use of one and two cameras per nest. Of 122 nests from 24 bird species, 45 (37%) were depredated, and the cameras recorded the predator species in 29 of the total of depredated nests (64%). We identified predators in eight of 16 depredated nests (50%) in which we used one camera trap per nest, and we identified predators in 21 of 29 depredated nests (72%) when we used two camera traps per nest. The predators included six species of birds and six species of mammals, with body masses varying from 20 g to 16.5 kg. Causes for 10 of the 16 detection failures were identified and are discussed. These results suggest that camera traps are viable tools to investigate nest predation in a tropical rainforest area.

scholarly journals Survival chances of ground nests in three different habitats in Krka National Park (Croatia)

2017 ◽  
Vol 118 (4) ◽  
Author(s):  
Jenő J Purger ◽  
Jasmina Mužinić
Keyword(s):  
Breeding Success ◽  
Nest Predation ◽  
Environmental Gradient ◽  
Survival Rates ◽  
Bird Species ◽  
Damage Rate ◽  
Daily Survival ◽  
Corvus Cornix ◽  
Reed Bed ◽  
Hooded Crows

Background and Purpose: Diverse Mediterranean wetlands sustain a high diversity of breeding birds. Breeding success of birds nesting on protected wetlands along river Krka is also influenced by predators. The aim of our study was to explore effects of predator pressures on ground nests of strictly protected birds using artificial nest located along environmental gradient. Materials and Methods: In May 2004 in locality Čulišićke bare, by placing out three batches of 25 artificially constructed ground nests in three different habitats: reed bed, marsh and meadow. The nests contained three chicken (real) eggs for the evaluation of nest predation rates, and plasticine (artificial) eggs for predator identification from tooth and bill imprints. Results and Conclusions: The number of nests depredated during one week was highest in wetland habitats: 52% was depredated in the marsh and 32% in the reed bed. However, a much lower damage rate (16%) was experienced in the meadow. The daily survival rate of nests did not differ significantly between the reed bed (0.95) and the marsh (0.91). However, the daily survival rates of nests in the meadow (0.98) was significantly higher (z = 2.49 P = 0.01) than in the marsh, bat no difference was found with comparing with the reed bed. Predators were difficult to determine because plasticine eggs usually disappeared from the nests in the reed bed. In the marsh and the meadow, primary predators were smaller birds, whereas small mammals were also important in the marsh. Nests in which predators succeeded in breaking at least one egg were later destroyed most by Hooded Crows (Corvus cornix). To apply these results for bird protection, the breeding success of certain threatened bird species should be monitored for a longer period.

scholarly journals Nestling begging calls increase predation risk by corvids

2019 ◽  
Vol 69 (2) ◽  
pp. 137-155
Author(s):  
Magne Husby
Keyword(s):  
Nest Predation ◽  
Predation Rate ◽  
Artificial Nest ◽  
Auditory Cues ◽  
Artificial Nests ◽  
Breeding Failure ◽  
Nestling Begging ◽  
Real Costs ◽  
Insight Into ◽  
Nest Predators

Abstract Despite nest predation being the most common cause of breeding failure in open-nesting birds, we have little insight into the cues used by nest predators when they search for nests. So far we have assumed that nest-predating birds are visually oriented while mammal predators to a large extent use scent and auditory cues like nestling begging calls. To evaluate how important nestling begging calls are for corvid nest predators searching for nests, I used artificial nests, which made it possible to find the real costs of the begging without mitigation by parental and nestling behavior. I used paired artificial nests, one with and one without nestling begging call playback. Within 10 days, 62.9% of the nests were predated. The analyses showed that nests with begging calls suffered a significantly higher predation rate than nests without begging calls, especially when the nests were placed close to corvid nests. Moreover, nests with begging calls were predated significantly earlier than nests without begging calls. In artificial nest pairs with both nests predated but on different days, nests with begging calls were predated first. In nest pairs with only one predated nest, nests with begging calls were predated most often. This experiment shows that nestling begging calls imply a cost in terms of increased and earlier nest predation, and that corvids use nestling begging calls as a cue to find and depredate bird nests, challenging earlier expectations.

scholarly journals Occurrence and relevance of Mycoplasma spp. in free-ranging pheasants from northwestern Germany

2022 ◽  
Vol 68 (1) ◽  
Author(s):  
Luisa Fischer ◽  
Jennifer Liebing ◽  
Iris Völker ◽  
Liane Baudler ◽  
Friederike Gethöffer ◽  
...  
Keyword(s):  
Population Decline ◽  
Bird Species ◽  
Tissue Samples ◽  
House Finches ◽  
The Usa ◽  
Potential Impact ◽  
Inflammatory Skin ◽  
Biological Methods ◽  
Free Ranging ◽  
Skin Samples

AbstractSince 2008/2009, the population of free-ranging ring-necked pheasants was recorded to decrease all over Germany. Various Mycoplasma (M.) spp. are causing severe respiratory signs in captive game bird species. Furthermore, M. gallisepticum is responsible for massive die-offs in consequence to severe conjunctivitis in house finches in the USA. Therefore, the prevalence of mycoplasmas in free-ranging pheasants was investigated and a potential impact on the population decline of pheasants discussed. Within this study, 150 free-ranging pheasants were sampled via tracheal swabs and tissue samples of the trachea and the periorbital skin, as the latter displayed inflammatory alterations in previous studies. In total, 177 samples were investigated for the presence of mycoplasmas using cultural and molecular biological methods. In 76 birds, necropsy was performed additionally. In total, 73.7% (51/76) of the examined pheasants had periorbital skin alterations. Furthermore, 64.4% (114/177) of the samples tested positive for mycoplasmas via PCR. Overall, 102/177 samples (57.6%, 78/105 tracheal swabs, 19/51 skin tissue, 5/21 trachea tissue) tested positive for mycoplasmas via culture. Mycoplasma gallinaceum (n = 50), M. pullorum (n = 45), M. glycophilum (n = 43), M. iners (n = 11), and M. gallinarum (n = 5) were frequently isolated. In 45 cases (45.9%), multiple Mycoplasma spp. were isolated from one sample. All examined samples tested negative for M. gallisepticum. Of 51 skin samples investigated for mycoplasmas, 24 (47.1%) showed inflammatory skin alterations in histology, and 58.3% (14/24) of these samples tested positive for Mycoplasma spp. additionally. Overall, there was a significant correlation between inflammatory altered skin samples and the detection of mycoplasmas in periorbital skin samples. Based on the present results, the isolated Mycoplasma spp. may play a role as facultative agents for the observed inflammatory skin alterations. However, additional investigation is needed to confirm this presumption.

scholarly journals Experimentally induced antipredator responses are mediated by social and environmental factors

2019 ◽  
Vol 30 (4) ◽  
pp. 986-992 ◽  
Author(s):  
Frank Groenewoud ◽  
Sjouke A Kingma ◽  
Kat Bebbington ◽  
David S Richardson ◽  
Jan Komdeur
Keyword(s):  
Predation Risk ◽  
Nest Predation ◽  
Bird Species ◽  
Ecological Factors ◽  
Antipredator Defense ◽  
Trade Offs ◽  
Future Reproduction ◽  
Female Investment ◽  
Predator Model ◽  
Nest Predator

AbstractNest predation is a common cause of reproductive failure for many bird species, and various antipredator defense behaviors have evolved to reduce the risk of nest predation. However, trade-offs between current reproductive duties and future reproduction often limit the parent’s ability to respond to nest predation risk. Individual responses to experimentally increased nest predation risk can give insights into these trade-offs. Here, we investigate whether social and ecological factors affect individual responses to predation risk by experimentally manipulating the risk of nest predation using taxidermic mounts in the cooperative breeding Seychelles warbler (Acrocephalus sechellensis). Our results show that dominant females, but not males, alarm called more often when they confront a nest predator model alone than when they do so with a partner, and that individuals that confront a predator together attacked more than those that did so alone. Dominant males increased their antipredator defense by spending more time nest guarding after a presentation with a nest predator, compared with a nonpredator control, but no such effect was found for females, who did not increase the time spent incubating. In contrast to incubation by females, nest guarding responses by dominant males depended on the presence of other group members and food availability. These results suggest that while female investment in incubation is always high and not dependent on social and ecological conditions, males have a lower initial investment, which allows them to respond to sudden changes in nest predation risk.

scholarly journals Breeding Biology of Passerines in a Subtropical Montane Forest in Northwestern Argentina

The Condor ◽  
2007 ◽  
Vol 109 (2) ◽  
pp. 321-333 ◽  
Author(s):  
Sonya K. Auer ◽  
Ronald D. Bassar ◽  
Joseph J. Fontaine ◽  
Thomas E. Martin
Keyword(s):  
Life History ◽  
Predation Risk ◽  
Nest Predation ◽  
Bird Species ◽  
Life History Strategies ◽  
Temperate Species ◽  
Egg Mass ◽  
Breeding Ecology ◽  
Feeding Rates ◽  
Northwestern Argentina

Abstract The breeding ecology of south temperate bird species is less widely known than that of north temperate species, yet because they comprise a large portion of the world's avian diversity, knowledge of their breeding ecology can contribute to a more comprehensive understanding of the geographic diversity of avian reproductive traits and life history strategies. We provide the first detailed examination of the reproductive strategies of 18 forest passerines of subtropical, northwestern Argentina. Mean clutch sizes were smaller and egg mass was greater than for north temperate birds, but differed among species and nest types, with cavity-nesters having larger clutches than species with open-cup and enclosed nests. Across all species, the average breeding season duration was 50 days; thus, the common perception that southern species have smaller clutch sizes because of longer breeding seasons is not supported in this community. Daily nest predation rates were influenced by nest type, cavity nests suffering the least from predation, as found in north temperate systems. Only females incubated eggs in all but one species, whereas both parents fed and cared for nestlings in all species. Mean nest attentiveness was low compared to north temperate passerines. Mean hourly nestling feeding rates differed among species and were negatively related to nest predation risk. In short, coexisting species in this subtropical forest varied in their life history strategies, in part correlated with variation in nest predation risk, but also differing from north temperate species.

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