Unravelling the annual cycle in a migratory animal: breeding-season habitat loss drives population declines of monarch butterflies

Many migratory species are declining and for most, the proximate causes of their declines remain unknown. For many long-distance Neotropical migratory songbirds, it is assumed that habitat loss on breeding or non-breeding grounds is a primary driver of population declines. We integrated data collected from tracking technology, community science and remote sensing data to quantify migratory connectivity (MC), population trends and habitat loss. We quantified the correlation between forest change throughout the annual cycle and population declines of a long-distance migratory songbird, the Connecticut warbler ( Oporornis agilis , observed decline: −8.99% yr −1 ). MC, the geographic link between populations during two or more phases of the annual cycle, was stronger between breeding and autumn migration routes (MC = 0.24 ± 0.23) than between breeding and non-breeding locations (MC = −0.2 ± 0.14). Different Connecticut warbler populations tended to have population-specific fall migration routes but overlapped almost completely within the northern Gran Chaco ecoregion in South America. Cumulative forest loss within 50 km of breeding locations and the resulting decline in the largest forested patch index was correlated more strongly with population declines than forest loss on migratory stopover regions or on wintering locations in South America, suggesting that habitat loss during the breeding season is a driver of observed population declines for the Connecticut warbler. Land-use practices that retain large, forested patches within landscapes will likely benefit breeding populations of this declining songbird, but further research is needed to help inform land-use practices across the full annual cycle to minimize the impacts to migratory songbirds and abate ongoing population declines.

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Myxomatosis in farmland rabbit populations in England and Wales

Epidemiology and Infection ◽

10.1017/s0950268800030703 ◽

1989 ◽

Vol 103 (2) ◽

pp. 333-357 ◽

Cited By ~ 23

Author(s):

J. Ross ◽

A. M. Tittensor ◽

A. P. Fox ◽

M. F. Sanders

Keyword(s):

Breeding Season ◽

Annual Cycle ◽

Seasonal Pattern ◽

Mortality Factor ◽

Mass Movements ◽

Wild Rabbit ◽

Regulatory Effect ◽

Methods Of Calculation ◽

Attenuated Virus ◽

Virus Strains

SUMMARYThe overall pattern and consequences of myxomatosis in wild rabbit populations were studied at three farmland sites in lowland southern England and upland central Wales between 1971 and 1978. When results from all years were combined, the disease showed a clear two-peaked annual cycle, with a main autumn peak between August and January, and a subsidiary spring peak during February to April.Rabbit fleas, the main vectors of myxomatosis in Britain, were present on full-grown rabbits in sufficient numbers for transmission to occur throughout the year, but the observed seasonal pattern of the disease appeared to be influenced by seasonal mass movements of these fleas. However other factors were also important including the timing and success of the main rabbit breeding season, the proportion of rabbits which had recovered from the disease and the timing and extent of autumn rabbit mortality from other causes.Significantly more males than females, and more adults and immatures than juveniles, were observed to be infected by myxomatosis. Only 25–27% of the total populations were seen to be infected during outbreaks. Using two independent methods of calculation, it was estimated that between 47 and 69% of infected rabbits died from the disease (much lower than the expected 90–95% for fully susceptible rabbits with the partly attenuated virus strains that predominated). Thus it was estimated that 12–19% of the total rabbit populations were known to have died directly or indirectly from myxomatosis.Although the effects of myxomatosis were much less than during the 1950s and 1960s, it continued to be an important mortality factor. It may still have a regulatory effect on rabbit numbers, with autumn/winter peaks of disease reducing the numbers of rabbits present at the start of the breeding season.

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Conspecific cues encourage Barn Swallow (Hirundo rustica erythrogaster) prospecting, but not nesting, at new nesting structures

The Canadian Field-Naturalist ◽

10.22621/cfn.v133i3.2233 ◽

2020 ◽

Vol 133 (3) ◽

pp. 235-245

Author(s):

Andrew J. Campomizzi ◽

Zoé M. Lebrun-Southcott ◽

Kristyn Richardson

Keyword(s):

Breeding Season ◽

Hirundo Rustica ◽

Population Declines ◽

Barn Swallow ◽

Nesting Habitat ◽

Southern Ontario ◽

Manipulative Experiments ◽

Barn Swallows ◽

Study Sites ◽

Conspecific Cues

Shed-like structures are being built to provide Barn Swallow (Hirundo rustica erythrogaster) nesting habitat in response to population declines. However, Barn Swallow use of these structures is unavailable in the literature. We conducted three manipulative experiments to test if adding conspecific cues (i.e., vocalizations and decoys) to newly-built structures affected prospecting visits by Barn Swallows (1) during pre-breeding, (2) during post-breeding, and (3) during or after broadcasts of vocalizations compared to before broadcasts. Additionally, we monitored nesting following pre- and post-breeding cues. We built one nesting structure with and one without conspecific cues at each of 10 study sites in southern Ontario, Canada where nesting habitat was recently lost. We detected about twice as many Barn Swallows immediately after conspecific broadcasts compared to before. We did not find substantial differences in abundance and interactions with new nesting structures for other comparisons involving conspecific cues. Following pre-breeding cues at 10 sites, six nests were built in three of 10 structures treated with conspecific cues, compared to five nests in four of 10 structures without cues. In the subsequent breeding season following post-breeding cues at eight sites, four nests were built in two of eight structures treated with conspecific cues, compared to four nests in three of eight structures without cues. Conspecific vocalizations appeared to increase prospecting behaviour, but not the number of nests, at new nesting structures. The paucity of nests on new structures suggests that building shed-like structures may not be an effective method of mitigating loss of nesting habitat.

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Reproduction of the Rabbit, Oryctolagus cunniculus (L.), on Macquarie Island, Subantarctic

Wildlife Research ◽

10.1071/wr9780317 ◽

1978 ◽

Vol 5 (3) ◽

pp. 317 ◽

Cited By ~ 7

Author(s):

IJ Skira

Keyword(s):

Breeding Season ◽

Annual Cycle ◽

First Year ◽

Corpora Lutea ◽

Macquarie Island ◽

Pregnant Females

The reproduction of rabbits on Macquarie I. was studied from December 1973 to February 1975. The breeding season extended from late August 1974 to mid-March 1975; both sexes showed an annual cycle in development and regression of the gonads. Between mid-October and mid-November 92% of females sampled were pregnant; during this period the maximum numbers of corpora lutea and embryos were 8.55 and 6.50 per female respectively. Few resorptions occurred although the number of pregnant females that resorbed increased as the breeding season progressed. Of all rabbit kittens produced in the 1974-75 breeding season, 64% were born by mid-December 1974. Female rabbits in their first year of breeding bore the greatest number of kittens; natality decreased as females aged.

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A poor substitute for the real thing: captive-reared monarch butterflies are weaker, paler and have less elongated wings than wild migrants

Biology Letters ◽

10.1098/rsbl.2019.0922 ◽

2020 ◽

Vol 16 (4) ◽

pp. 20190922 ◽

Cited By ~ 3

Author(s):

Andrew K. Davis ◽

Farran M. Smith ◽

Ashley M. Ballew

Keyword(s):

Danaus Plexippus ◽

Late Summer ◽

Population Declines ◽

Average Strength ◽

Long Distance ◽

Monarch Butterflies ◽

Real Thing ◽

In The Wild ◽

Wild Group ◽

Migration Propensity

For many animals and insects that are experiencing dramatic population declines, the only recourse for conservationists is captive rearing. To ensure success, reared individuals should be biologically indistinct from those in the wild. We tested if this is true with monarch butterflies, Danaus plexippus , which are increasingly being reared for release by citizens and commercial breeders. Since late-summer monarchs should be as migration capable as possible for surviving the arduous long-distance migration, we evaluated four migration-relevant traits across two groups of captive-reared monarchs ( n = 41 and 42) and one group of wild-caught migrants ( n = 41). Monarchs (descendants of wild individuals) were reared from eggs to adulthood either in a warm indoor room next to a window, or in an incubator that mimicked late-summer conditions. Using an apparatus consisting of a perch mounted to an electronic force gauge, we assessed ‘grip strength' of all groups, then used image analysis to measure forewing size, pigmentation and elongation. In three of the four traits, reared monarchs underperformed compared to wild ones, even those reared under conditions that should have produced migration-ready individuals. The average strength of reared monarchs combined was 56% less than the wild group, even when accounting for size. Their orange wing colour was paler (an indicator of poor condition and flight ability) and their forewings were less elongated (elongation is associated with migration propensity) than wild monarchs. The reason(s) behind these effects is unknown but could stem from the frequent disturbance and/or handling of reared monarchs, or the fact that rearing removes the element of natural selection from all stages. Regardless, these results explain prior tagging studies that showed reared monarchs have lower migratory success compared to wild.

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Seasonal changes in distribution and abundance of a local Corncrake population

Journal of Ornithology ◽

10.1007/s10336-020-01827-z ◽

2020 ◽

Author(s):

Michał Budka ◽

Patryk Kokociński ◽

Paweł Bogawski ◽

Maciej Nowak ◽

Joanna Teresa Białas ◽

...

Keyword(s):

Population Size ◽

Breeding Season ◽

Site Fidelity ◽

Vegetation Index ◽

Normalized Difference Vegetation Index ◽

Local Population ◽

Bird Species ◽

Adult Males ◽

Habitat Conditions ◽

Population Declines

Abstract Many bird species have experienced short- or long-term population declines. However, the mechanisms and reasons underlying such negative changes are often not fully understood, making it difficult to identify effective conservation measures to recover populations. In this study, we focused on local changes in the abundance and distribution of calling male Corncrakes Crex crex in relation to: (1) within- and between-season site fidelity of adult males, (2) spatial distribution of territories in consecutive years and (3) the effect of habitat conditions on population size. We counted the number of calling males at ten randomly selected study plots (1 km2) in 2014–2018. Additionally, males were caught and individually marked in years 2015–2017. We found significant between-year changes in Corncrake abundance, from a 34% decrease to a 21% increase. On average, 32% of males established territories in the same locations as males recorded in the previous year. Breeding site fidelity was very low, with only 2–5% of males recaptured in the following year. Males selected areas characterized by higher values of NDVI (Normalized Difference Vegetation Index–higher values indicate more biomass) than on average within the study area. Population size in a particular year was significantly affected by the NDVI of the previous year but not by the NDVI in the current breeding season. We suppose that Corncrakes may exhibit a nomadic breeding behavior, and settle at territories when they encounter optimal habitat conditions. Moreover, as population size was negatively correlated with habitat conditions at the beginning of the previous breeding season, we suppose that local population changes may reflect more general trends in a whole population rather than local breeding success. Therefore, we highlight the need for better knowledge of Corncrake dispersal within the main European population and for the coordination of monitoring and conservation efforts, especially in those regions where most Corncrakes breed.

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A population survey of the estuarine crocodile in the Ayeyarwady Delta, Myanmar

Oryx ◽

10.1046/j.1365-3008.2000.00135.x ◽

2000 ◽

Vol 34 (4) ◽

pp. 317-324 ◽

Cited By ~ 5

Author(s):

John Thorbjarnarson ◽

Steven G. Platt ◽

U. Saw Tun Khaing

Keyword(s):

Law Enforcement ◽

Survey Data ◽

Habitat Loss ◽

Population Survey ◽

Total Population ◽

Population Declines ◽

Wildlife Sanctuary ◽

Coastal Regions ◽

The Status ◽

Crocodylus Porosus

AbstractThe estuarine crocodile Crocodylus porosus was formerly abundant in coastal regions of Myanmar, but is now known principally from the lower Ayeyarwady Delta. We conducted a survey during January 1999 to assess quantitatively the status of crocodile populations in protected areas of the lower delta. Spotlight counts were conducted along 275.4 km of waterways. Sixty-one crocodiles (50 juveniles, 4 subadults, 2 adults and 5 eyeshines) were observed in the Meinmahla Kyun Wildlife Sanctuary (MKWS), and the total population was estimated to be less than 100. The Kadônkani and Pyindaye Reserved Forests (RF) apparently no longer support viable populations. Although crocodiles remain critically endangered in the region, a comparison with survey data from 1980 suggests localized recovery is occurring in MKWS. Population declines are attributed to a combination of commercial skin hunting, habitat loss, drowning in fishing nets and over-collection of living animals to supply crocodile farms. A programme of law enforcement, habitat protection and head-starting juveniles is necessary to ensure the continued survival of estuarine crocodiles in the Ayeyarwady Delta.

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Cryptic and cumulative impacts on the wintering habitat of the endangered black-faced spoonbill (Platalea minor) risk its long-term viability

Environmental Conservation ◽

10.1017/s0376892917000340 ◽

2017 ◽

Vol 45 (2) ◽

pp. 147-154 ◽

Cited By ~ 2

Author(s):

EVAN J. PICKETT ◽

MELANIE CHAN ◽

WENDA CHENG ◽

JOHN ALLCOCK ◽

SIMBA CHAN ◽

...

Keyword(s):

Climate Change ◽

Habitat Loss ◽

Population Change ◽

Anthropogenic Impacts ◽

Population Viability Analysis ◽

Cumulative Impacts ◽

Population Declines ◽

Distribution Models ◽

Waterbird Species

SUMMARYThe East Asian–Australasian flyway contains some of the most threatened habitats in the world, with at least 155 waterbird species reliant on the tidal habitats it comprises. The black-faced spoonbill (Platalea minor) is an iconic endangered species distributed across the coast of East Asia. Its population suffered a severe decline into the 1990s, but extensive monitoring and conservation interventions have aided a substantial recovery of the species. We used a population viability analysis based on data collected over the past two decades in conjunction with species distribution models to project spatially explicit models of population change for the next 35 years. Over nearly all scenarios of habitat loss and climate change, the global spoonbill population was projected to increase in the short-term due to low population numbers likely well below current population carrying capacities. However, climate change and habitat loss together threaten the recovery of the spoonbill population such that, by 2050, population declines are apparent as a consequence of these cumulative impacts. These threats are also cryptic and represent a challenge to the conservation of species recovering from anthropogenic impacts; observed population increases can hide large reductions in habitat suitability that threaten the long-term viability of species.

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A call for full annual cycle research in animal ecology

Biology Letters ◽

10.1098/rsbl.2015.0552 ◽

2015 ◽

Vol 11 (8) ◽

pp. 20150552 ◽

Cited By ~ 192

Author(s):

Peter P. Marra ◽

Emily B. Cohen ◽

Scott R. Loss ◽

Jordan E. Rutter ◽

Christopher M. Tonra

Keyword(s):

Annual Cycle ◽

Animal Movement ◽

Population Level ◽

Vertebrate Species ◽

Anthropogenic Change ◽

Population Declines ◽

Concerted Effort ◽

Annual Cycles ◽

Research Bias ◽

Recent Emergence

For vertebrates, annual cycles are organized into a series of breeding and non-breeding periods that vary in duration and location but are inextricably linked biologically. Here, we show that our understanding of the fundamental ecology of four vertebrate classes has been limited by a severe breeding season research bias and that studies of individual and population-level responses to natural and anthropogenic change would benefit from a full annual cycle perspective. Recent emergence of new analytical and technological tools for studying individual and population-level animal movement could help reverse this bias. To improve understanding of species biology and reverse the population declines of many vertebrate species, a concerted effort to move beyond single season research is vital.

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Synergistic impacts of habitat loss and fragmentation on model ecosystems

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2016.1027 ◽

2016 ◽

Vol 283 (1839) ◽

pp. 20161027 ◽

Cited By ~ 13

Author(s):

Lewis J. Bartlett ◽

Tim Newbold ◽

Drew W. Purves ◽

Derek P. Tittensor ◽

Michael B. J. Harfoot

Keyword(s):

Land Use ◽

Habitat Loss ◽

Plant Biomass ◽

Synergistic Effects ◽

Ecosystem Model ◽

Ecosystem Structure ◽

Population Declines ◽

Ecosystem Responses ◽

Habitat Loss And Fragmentation ◽

Biomass Loss

Habitat loss and fragmentation are major threats to biodiversity, yet separating their effects is challenging. We use a multi-trophic, trait-based, and spatially explicit general ecosystem model to examine the independent and synergistic effects of these processes on ecosystem structure. We manipulated habitat by removing plant biomass in varying spatial extents, intensities, and configurations. We found that emergent synergistic interactions of loss and fragmentation are major determinants of ecosystem response, including population declines and trophic pyramid shifts. Furthermore, trait-mediated interactions, such as a disproportionate sensitivity of large-sized organisms to fragmentation, produce significant effects in shaping responses. We also show that top-down regulation mitigates the effects of land use on plant biomass loss, suggesting that models lacking these interactions—including most carbon stock models—may not adequately capture land-use change impacts. Our results have important implications for understanding ecosystem responses to environmental change, and assessing the impacts of habitat fragmentation.

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