Global warming makes it harder for birds to mate, study finds

SEPTEMBER 17, 2019

by University of East Anglia

New research led by the University of East Anglia (UEA) and University of Porto (CIBIO-InBIO) shows how global warming could reduce the mating activity and success of grassland birds.

The study examined the threatened grassland bird Tetrax tetrax, or little bustard, classified as a vulnerable species in Europe, in order to test how rising temperatures could affect future behavior.

The males spend most of their time in April and May trying to attract females in a breeding gathering known as a lek. In leks, to get noticed, males stand upright, puff up their necks, and making a call that sounds like a 'snort." They also use this display to defend their territory from competing breeding males.

The international team of researchers—from the UK, Kenya, Portugal, Spain and Brazil—found that high temperatures reduced this snort-call display behavior. If temperatures become too hot, birds may have to choose between mating and sheltering or resting to save their energy and protect themselves from the heat.

Published in the journal PLOS ONE, the findings show that during the mating season little bustard display behavior is significantly related to temperature, the time of the day—something referred to as circadian rhythms—and what stage of the mating season it is. The average temperature during the day also affects how much birds display and again as temperatures increase, display rates reduce.

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Invasive forage grass leads to grassland bird decline

Date:  October 19, 2018

Source:  University of Illinois College of Agricultural, Consumer and Environmental Sciences

The prairies of North America once covered vast stretches of land, with towering grasses creating ideal nesting and forage habitat for grassland birds. But the deep, rich soil and treeless expanse also represented the ideal conditions for farming -- both row crops and cattle grazing -- in the eyes of settlers. Today, largely thanks to agricultural conversion, a mere 1 percent of tallgrass prairie remains. And what's left is now being threatened by invasive species and forest encroachment.

"With grasslands in steep decline, the birds that depend on them are also disappearing. Therefore, it is urgent that we understand how these more recent changes -- invasive species and landscape shifts -- influence grassland bird reproduction," says Scott Maresh Nelson, a doctoral student advised by Professor Jim Miller in the Department of Natural Resources and Environmental Sciences (NRES) at the University of Illinois.

In a recent study published in Landscape Ecology, Maresh Nelson and his colleagues found that a common cattle forage grass, tall fescue, is associated with nest failure in dickcissels, small grassland birds similar to sparrows.

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Study provides video evidence of parental infanticide in a grassland bird species

April 19, 2018, University of Illinois at Urbana-Champaign

Baby birds go missing from their nests all the time. Usually, the disappearances are chalked up to predation, but in extremely rare cases, parents have been observed removing their own chicks from their nests. In a new study from the University of Illinois, the mysterious and fatal behavior is documented in dickcissels for the first time.

"In the early days, chicks can't survive outside the nest. They can't regulate their temperature," says Jaime Coon, lead author of the paper and graduate student in the Department of Natural Resources and Environmental Sciences at U of I.

The researchers didn't go looking for birds committing parental infanticide. They had been monitoring dickcissel nests as part of a larger ongoing study examining the effects of fire, grazing, and herbicide application on the grassland-dwelling species. The team trained high-definition video cameras on the nests to monitor diet and feeding behavior.

Coon says these cameras are a huge leap forward for nest monitoring because they provide much greater resolution than traditional monitoring tools. The downside? The batteries only last a few hours. The fact that they caught this rare behavior in such a short timeframe is what makes the discovery so surprising.

In the video, the mother bird can be seen grasping a chick by the leg and carrying it out of the nest. "It's kind of brutal," Coon says.

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Grassland Birds Likely Dying Off From Habitat Loss, Not Insecticide Use

Contrary to publicized research, the decline in grassland bird populations may be related to habitat loss and not insecticide use.

Last year two researchers linked the drop in grassland bird population to insecticide use, but after a reexamination of the data suggests the loss of grasslands is a more likely cause, a Penn State news release reported.

"Many people think of grassland loss as something that happened long ago in North America, but the amount of grassland lost since the 1980s is absolutely staggering, whereas the insecticide use greatly declined prior to the 1990s," Jason M. Hill, a postdoctoral research associate in ecosystem science and management, Penn State said in the news release.

The researchers looked at data that showed a loss of grasslands larger than the state of Indiana between the years of 1982 and 1997; this loss was linked to the expansion of agricultural practices.

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Technology helps scientists track grassland birds that come through Colorado

By Deborah Huth Price For the Reporter-Herald

Posted:   04/10/2013 07:19:50 PM MDT

The lark bunting (Colorado s state bird) depends on grasslands for survival. Breeding males are black with white wings. (José Hugo Martínez Guerrero)

Not all birds live in trees -- many bird species depend on open grasslands for food and shelter, and their habitat is disappearing. Some of these little birds carry miniature transmitters and geo-locators on their backs, helping scientists understand migratory patterns, wintering grounds and survival needs.

lark bunting

Greg Levandoski, director of operations for the international program of Rocky Mountain Bird Observatory (RMBO), along with his colleagues, has been studying and researching grassland birds as they migrate from Colorado and states farther north to the southern United States and Mexico. He concentrates on the Chihuahuan Desert, where he says there are 15-17 grassland priority conservation areas that biologists and conservationists think are the most important grasslands remaining. Their research area covers Arizona, New Mexico, Texas and six states in Mexico.

According to RMBO information, the Chihahuan desert provides primary wintering grounds for more than 90 percent of grassland birds in western North America. These range from raptors to songbirds, including the Baird's and grasshopper sparrows, mountain plover, Ferruginous hawk, western meadowlark and Colorado's state bird, the lark bunting. RMBO has about 140 species of grassland birds in their database, and focus on about 30 high-priority species that either benefit from or require grasslands.

Follow the Birds

Learn more about migratory birds by attending the International Migratory Bird Celebration May 11 in Fort Collins: . The event includes bird banding stations, activities, and a bike, bird and brew tour.

"It's hard to help them and conserve them if you don't understand their needs," says Levandoski. To do this, RMBO has acquired grants and established partnerships with organizations such as the city of Fort Collins, U.S. Fish and Wildlife Service, Neotropical Migratory Bird Conservation Act, the Universidad Autnoma de Nuevo Leon in Monterrey, Mexico, and other organizations and agencies.

In order to better understand the birds' migratory paths and preferred wintering grounds, Levandoski says researchers captured and placed tiny radio transmitters on Baird's and grasshopper sparrows. "We have people out in the field every day with an antenna and a headset and they listen for little beeps broadcast by the transmitters."

A newer technology allowed researchers to use geolocators on black swifts. These small light sensors are attached to birds' backs and record daylight length and intensity. "Using calculations similar to those mariners used to make, you can figure out latitude and longitude," Levandoski explains. The instruments do not transmit data, but store information, which is then collected by recapturing birds the next year. Geo-locators are now getting small enough that Levandoski hopes they may soon be used on sparrows.

Grassland birds vary in their migratory ranges. Baird's sparrows breed in North Dakota, Montana and the Saskatchewan areas, flying south to Mexico in the winter. Grasshopper sparrows are much more widespread, shares Levandoski. "We have them on city properties breeding in summertime." These and many other seed-eating birds need a large network of grasslands to exist and thrive. Levandoski says that "Of all the groups of birds on the continent, probably worldwide, grassland birds have been the most affected and have had the most widespread population decline."

"One of the important lessons we've learned," says Levandoski, "is that due to the random nature of where rain falls each year in the desert, it's really important that we conserve a whole network of grasslands. Many of these species seem to shift the bulk of their wintering populations year to year depending on where the rain fell and where grass is in good condition."

Read on:  http://www.reporterherald.com/lifestyles/recreation/ci_22990210/technology-helps-scientists-track-grassland-birds-that-come

Pesticides, including neonicotinoids, leading cause of decline of grassland birds

New study finds pesticides leading cause of grassland bird declines

February 2013. A new study led by a preeminent Canadian toxicologist identifies acutely toxic pesticides as the most likely leading cause of the widespread decline in grassland bird numbers in the United States, a finding that challenges the widely-held assumption that loss of habitat is the primary cause of those population declines.

The scientific assessment, which looked at data over a 23-year period - from 1980 to 2003, was conducted by Dr. Pierre Mineau, recently retired from Environment Canada, and Mélanie Whiteside of Health Canada.

The study looked at five potential causes of grassland bird declines besides lethal pesticide risk: change in cropped pasture such as hay or alfalfa production, farming intensity or the proportion of agricultural land that is actively cropped, herbicide use, overall insecticide use, and change in permanent pasture and rangeland.

Spotlight on acutely toxic insecticides used on cropland
"What this study suggests is that we need to start paying a lot more attention to the use of pesticides if we want to reverse, halt or simply slow the very significant downward trend in grassland bird populations. Our study put the spotlight on acutely toxic insecticides used on cropland starting after the Second World War and persisting to this day - albeit at a lower level. The data suggest that loss of birds in agricultural fields is more than an unfortunate consequence of pest control; it may drive bird populations to local extinction," Mineau said.

Many grassland bird species have undergone range contractions or population declines in recent decades. In fact, analyses of North American birds indicate that these birds are declining faster than birds from other biomes. Habitat protection has long been considered a central pillar in efforts to stem the decline of grassland bird species, such as the Vesper Sparrow, the Ring-necked Pheasant, and the Horned Lark.

Continued: http://www.wildlifeextra.com/go/news/grassland-birds.html

Conservation Plan Addresses Decline of Grassland Birds

The Rocky Mountain Bird Observatory has released the first-ever conservation plan for grassland bird species that winter in the Chihuahuan Desert, with support from the Rio Grande Joint Venture and American Bird Conservancy. The plan provides a wide range of science-based information to guide everyone from on-the-ground land managers to program- and policy-level decision-makers in maintaining and improving habitat for grassland bird species of high conservation concern.

Grassland birds have declined more steeply than any other group of North American birds. 

To address this concern, the Chihuahuan Desert Grassland Bird Conservation Plan focuses on providing an understanding of the distribution, abundance and habitat associations of five declining grassland bird species: Baird's Sparrow, Chestnut-collared Longspur, Lark Bunting, Sprague's Pipit and Loggerhead Shrike. All five of these species appear on the U.S. Fish & Wildlife Service's Birds of Conservation Concern list for Bird Conservation Region 35, which encompasses the Chihuahuan Desert in the southwestern U.S. and northern Mexico.

Continued:  http://rmbo.org/v3/Home/tabid/41/EntryId/37/Conservation-Plan-Addresses-Decline-of-Grassland-Birds.aspx