Tag Archives: population

Population trends, threats, and conservation recommendations for waterbirds in China

(Xiaodan Wang, Fenliang Kuang, Kun Tan and Zhijun M 28 April 2018)

Background

China is one of the countries with abundant waterbird diversity. Over the past decades, China’s waterbirds have suffered increasing threats from direct and indirect human activities. It is important to clarify the population trends of and threats to waterbirds as well as to put forward conservation recommendations.

Methods

We collected data of population trends of a total of 260 waterbird species in China from Wetlands International database. We calculated the number of species with increasing, declining, stable, and unknown trends. We collected threatened levels of waterbirds from the Red List of China’s Vertebrates (2016), which was compiled according to the IUCN criteria of threatened species. Based on literature review, we refined the major threats to the threatened waterbird species in China.

Results

Of the total 260 waterbird species in China, 84 species (32.3%) exhibited declining, 35 species (13.5%) kept stable, and 16 species (6.2%) showed increasing trends. Population trends were unknown for 125 species (48.1%). There was no significant difference in population trends between the migratory (32.4% decline) and resident (31.8% decline) species or among waterbirds distributed exclusively along coasts (28.6% decline), inland (36.6% decline), and both coasts and inland (32.5% decline). A total of 38 species (15.1% of the total) were listed as threatened species and 27 species (10.8% of the total) Near Threatened species. Habitat loss was the major threat to waterbirds, with 32 of the total 38 (84.2%) threatened species being affected. In addition, 73.7% (28 species), 71.1% (27 species), and 57.9% (22 species) of the threatened species were affected by human disturbance, environmental pollution, and illegal hunting, respectively.

Conclusions

We propose recommendations for waterbird conservation, including (1) strengthening conservation of nature wetlands and restoration of degraded wetlands, (2) enhancing public awareness on waterbird conservation, (3) improving the enforcement of Wildlife Protection Law and cracking down on illegal hunting, (4) carrying out long-term waterbird surveys to clarify population dynamics, (5) restoring populations of highly-threatened species through artificial intervention, and (6) promoting international and regional exchanges and cooperation to share information in waterbirds and their conservation.

 

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A total of 38 species (14.6% of the total) have been listed as threatened species, including 6 species (2.4%) being listed as Critically Endangered, 16 species (6.4%) Endangered, and 16 species Vulnerable (6.4%). Another 27 species (10.8%) were listed as Near Threatened (Table 2). In addition, 54 species (21.5%) were not assessed due to data deficiency or their marginal distribution in China. The threatened species were mainly in the Orders of Gruiformes (10 species), Charadriiformes (10 species), Anseriformes (8 species), and Pelecaniformes (8 species). The highest proportion of threatened species was in the Order of Ciconiiformes (40.0%) (Table 3). Although the percentage of threatened waterbird species in China (15.1% of the total) was slightly lower than that the global level (18.8%) (Wetland International 2012), the percentage of non-assessed species in China (21.5%) was much higher than that globally (0.4%).TABELL.PNG

Read the complete research report here

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Stor genomgång: Hur går det för Sveriges fåglar?

kungsfågel.PNG

(Erik Hansson, Natursidan; 13 april 2018; Foto Daniel Pettersson )

Sveriges fågelfauna blir allt större när fler fåglar börjar häcka här. Det går också allt bättre för många arter, men sämre för jordbruksfåglarna och de krävande skogsfåglarna. Det visar rapporten ”Sveriges fåglar 2018” från BirdLife Sverige, gjord i samarbete med Lunds universitet, Naturvårdsverket, landets länsstyrel­ser, ArtDatabanken och inte minst insatser från ungefär 600 frivilliga.

Sveriges fåglar har kartlagts av BirdLife Sverige (Sveriges Ornitologiska Förening) i drygt 70 år och sedan 1970-talet har verksamheten ”utökats och förstärkts av mera vetenskapliga inventeringar inom ramen för det som idag är Svensk Fågeltaxering”.

– Vi vågar påstå att vi idag har en bra bild av hur det går för Sveriges fåglar, såväl i landet som helhet som i olika landskapstyper. Denna kunskap växer dessutom genom att vi under senare tid utökat inventeringsprogrammen. Samtidigt är det viktigt att påpeka att fågelfaunan är föränderlig och att den ständigt påverkas av olika faktorer i omvärlden. Detta gäller inte minst hur vi utnyttjar och påverkar naturen, skriver Anders Wirdheim i publikationen Sveriges fåglar 2018.

En av metoderna som används är de så kallade standardrutterna. Drygt 600 inventerare, som alla är duktiga fågelskådare, följer en förutbestämd, 8 km lång runda i form av en kvadrat med 2 km sida. Dessa rutor är jämnt fördelade över landet och anses ge en representativ bild av den svenska fågelfaunan.

Det går bra för många fåglar
Rapporten ”Sveriges fåglar 2018” visar både väldigt positiva och negativa exempel. Det har exempelvis de senaste 10 åren gått väldigt bra för sångsvan, storskrake, havsörn, tornfalk, trana, silltrut, sydlig gulärla, gärdsmyg, tofsmes, nötkråka, steglits, domherre och stenknäck och många vadare såsom nordlig kärrsnäppa och rödbena. Allra starkast ökning uppvisar bland andra gransångare, gråsiska, brushane och fjällripa.

– Det är nog ingen som vet varför fjällripan ökat i antal under senare tid samtidigt som trenden för dalripan länge varit nedåtgående, berättar rapportens författare Anders Wirdheim. Men en delförklaring skulle kunna vara …

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Snowy owl numbers far lower than once thought

Snowy owl migration gives scientists chance to study them
(Tammy Webber 21 Dec 2017)

Scott Judd trained his camera lens on the white dot in the distance. As he moved up the Lake Michigan shoreline, the speck on a breakwater came into view and took his breath away: it was a snowy owl, thousands of miles from its Arctic home.

“It was an amazing sight,” said Judd, a Chicago IT consultant. “It’s almost like they’re from another world. They captivate people in a way that other birds don’t.”

The large white raptors have descended on the Great Lakes region and northeastern U.S. in huge numbers in recent weeks, hanging out at airports, in farm fields, on light poles and along beaches, to the delight of bird lovers.

But for researchers, this winter’s mass migration of the owls from their breeding grounds above the Arctic Circle is serious business.

It’s a chance to trap and fit some of the visitors with tiny transmitters to help track them around the globe and study a long-misunderstood species whose numbers likely are far fewer than previously thought, researchers say.

“There is still a lot that we don’t know about them … but we aim to answer the questions in the next few years,” said Canadian biologist Jean-Francois Therrien, a senior researcher at Hawk Mountain Sanctuary in Pennsylvania.

The solar-powered transmitters can last for years, collecting information such as latitude, longitude, flight speed and air temperature that is downloaded to a server when the birds fly into range of a cell tower.

The use of transmitters, which intensified during the last North American mass migration in winter 2013-14, already has yielded big surprises.

Instead of 300,000 snowy owls worldwide, as long believed, researchers say the population likely is closer to 30,000 or fewer. The previous estimate was based on how many might be able to breed in a given area.

That calculation was made assuming snowy owls acted like other birds, favoring fixed nesting and wintering sites. But researchers discovered the owls are nomads, often nesting or wintering thousands of miles from previous locations.

The miscalculation doesn’t necessarily mean snowy owls, which can grow to about 2 feet long with 5-foot wingspans, are in decline. Scientists simply don’t know because they never had an accurate starting point.

This month, snowy owls were listed as vulnerable—one step away from endangered—by the International Union for Conservation of Nature. They’re protected in the U.S. under the Migratory Bird Act.

This year’s mass migration is a bit of good news. Researchers once thought these so-called “irruptions” signaled a lack of prey in the Arctic, but now believe the opposite: Breeding owls feed on lemmings, a rodent that lives under Arctic snowpack and whose population surges about every three or four years. More lemmings means the owl population explodes— and that more birds than usual will winter in places people can see them.

 But researchers worry that climate change will affect the owl population because lemmings are exceptionally sensitive to even small temperature changes.

Lemmings “depend on deep, fluffy, thick layers of insulating snow” to breed successfully, said Scott Weidensaul, director at Project SNOWstorm, an owl-tracking group whose volunteers have put transmitters on more than 50 snowy owls in the past four years .

The snowy owl population collapsed in Norway and Sweden in the mid-1990s, all but vanishing there for almost two decades before reappearing at lower numbers, experts said. In Greenland, where the population collapsed in the late 1990s, researchers found a few nests in 2011 and 2012 after six years with no recorded nests, but owls didn’t come back in 2016 or 2017, when lemmings should have been peaking.

The National Oceanic and Atmospheric Administration reported this month that the far northern Arctic is warming twice as fast as the rest of the globe.

But it’s tough to assess lemming population trends in remote areas. Although researchers hope to enlist native villagers to help, it’s mostly up to owls with transmitters for now.

Snowy owls somehow seem to find lemmings even if they are thousands of miles from where their population last peaked, Therrien said.

“They look around the Arctic,” he said. “The movement is amazing to watch on a map: There are no straight lines. They’re zigzagging.”

Norman Smith, a snowy owl expert with Mass Audubon in Massachusetts, said he’s heartened that many independent researchers worldwide joined forces to share information on snowy owls.

“It’s amazing what we’ve learned, but we need a bigger database of birds,” said Smith, who has been trapping owls at Boston’s Logan International Airport for more than 35 years and fits them with a leg band or transmitter before letting them go. He put a satellite tracker on an owl for the first time in 2000, proving that they could make it back to the Arctic.

Last week, Smith released a young female on a barrier beach along the Atlantic Ocean. It flew south, then circled back and flew overhead. As he drove over a bridge to the mainland, the owl was sitting on a post, surveying its new winter home.

Snowy owl migration gives scientists chance to study them

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Fifty years on, the Breeding Bird Survey continues to produce new insights

(Science Daily, American Ornithological Society 26 July 2017)

In 1966, a U.S. Fish and Wildlife Service biologist named Chan Robbins launched an international program designed to measure changes in bird populations using volunteers recruited to count birds on pre-set routes along country roads. The result, the North American Breeding Bird Survey or BBS, is still going strong more than five decades later. This month The Condor: Ornithological Applications is publishing a special set of research papers to honor the program’s fiftieth anniversary.

Unassuming but visionary, Robbins had studied DDT’s effects on birds — his reports were edited by Rachel Carson — and he wanted to devise a way of monitoring the health of the continent’s bird populations on a large scale. The simple field protocols he developed, able to be carried out by volunteer birdwatchers, have remained largely the same since the program’s inception. Today, there are more than 4100 survey routes spanning North America from Alaska to Newfoundland, Florida, and northern Mexico.

The BBS provides long-term data for 424 species, with more limited data for an additional 122. Since data collection began in the 1960s, significantly more species have been declining than increasing. Looking at patterns of change in groups of birds sharing common attributes can be especially useful; for example, only 8 of 24 grassland bird species have seen increases. However, in the short term the picture is slightly rosier — since the survey area was expanded in 1993, 56% of the species surveyed have showed positive trends. Today, modern statistical techniques are letting ornithologists glean more insight from BBS data than ever before.

“The BBS is the only source of long-term, multi-scale population change information for more than 500 species of North American birds,” according to the USGS’s John Sauer, who has worked with the BBS since 1986 and was one of the co-editors for the special section along with Keith Pardieck and Colleen Handel, also with the USGS. “BBS results have allowed conservationists to identify bird species and regions undergoing population declines, alerting the public and scientists to population changes and facilitating the development of initiatives to better understand declines.”

The papers that make up the special section in The Condor include:

  • Prioritizing areas for conservation by combining six years of BBS data with remotely sensed environmental data to model the predicted distribution of seven grassland bird species in the Northern Great Plains based on their habitat needs.
  • Statistical approaches for model selection in BBS analyses.
  • Combining BBS with off-road surveys to estimate population changes for birds that breed in Alaska, where habitats are being rapidly altered due to climate change.
  • Using long-term BBS data to rank the vulnerability of more than 460 landbird species, set population objectives, and track progress toward meeting conservation goals.
  • Analyzing how well road-based BBS routes represent larger landscapes, using data from 2011 National Land Cover Database, with the conclusion that any land-cover-based roadside bias in BBS data is likely minimal.
  • Combining BBS data with separate demographic data to estimate the size of the Atlantic Flyway’s Wood Duck population.
  • Plus, a review of how the BBS has informed North American bird conservation since its inception.

The papers grew out of a research symposium held at last summer’s North American Ornithological Conference in Washington, DC, to commemorate 50 years of the BBS. “The BBS provides a fundamental tool for understanding breeding bird distribution and abundance. We’re pleased to publish these papers that celebrate Chan Robbins’s vision and the hard work of thousands of volunteers through the latest results and analyses,” said Philip Stouffer, Editor-in-Chief of The Condor: Ornithological Applications.