Birds & Science

We use the best available science to ensure the survival of Montana's birds and other wildlife.

Colonial Waterbirds

Colonial Waterbird Surveys in Montana

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Many states in the western U.S., including Montana, recognize that understanding colonial waterbird distribution and populations is a priority to determine conservation status, identify potential threats, and develop conservation plans affecting these species’ habitats.

Colonial waterbirds are those that share two major characteristics: communal nesting in groups of a few individuals to a few thousand birds, and a reliance on water to sustain their food resources. There are 18 colonial waterbird species in Montana that regularly use our marsh vegetation, lush river habitats, trees, islands, and sandbars for nesting. However, 2016 marked the first year that evidence of nesting Cattle Egrets* was recorded in the state, raising the count total to 19 species.


We recently summarized facts about this unique group of birds and our eight-year survey effort into a visually stunning, colonial waterbirds poster: Montana Audubon Waterbirds

A survey of colonial waterbirds (see species list below) was coordinated by U.S. Fish and Wildlife Service and implemented in our state by Montana Fish, Wildlife and Parks (FWP) during 2009, 2010, and 2011 (for details see Western Colonial Waterbird Survey Protocols).

From 2012-2017, Montana Audubon worked with FWP, Fred Tilly, and others including individual Wildlife Refuge biologists, to continue the surveys in areas considered key sites.  Montana Audubon and the Montana Bird Conservation Partnership work collaboratively to continue with this effort.


Colonial Waterbirds and Climate Change

Predicted changes in precipitation and temperature due to climate change indicate that wetland habitats colonial nesting birds are reliant upon will be reduced in area. Wetlands are predicted to become less capable of controlling flood waters, capturing sediment, and replenishing groundwater resources, which are ecosystem services they have historically provided. The prairie pothole region, which includes many of the shallow wetlands of eastern Montana, is expected to experience more drought conditions, and the resulting loss of wetlands could be dramatic. Further, many wetland systems are seasonal or semi-permanent, so increased rates of evaporation alone can cause these habitats to decline. Birds dependent on these shallow sites are particularly vulnerable such as the White-faced Ibis, Black-crowned Night Heron, and Clark’s Grebe.

In 2014 the National Audubon Society conducted a study that revealed 314 North American bird species were “threatened” or “endangered” by climate change, and this includes 16 of Montana’s 18 waterbird species. Only two, Great Blue Heron and Snowy Egret could not be categorized because of a lack of specific data. Being designated as climate-threatened means that the species is expected to lose 50% of their range by 2080 and climate-endangered means that 50% loss could occur as soon as 2050. Six of Montana’s colonial waterbirds are threatened, while ten are endangered by climate change.

Read more about birds and climate in Montana


REPORTS:

For more information contact Allison Begley, [email protected] 406.444.3370

Priority species

  • American White Pelican
  • Clark’s Grebe
  • Forster’s Tern
  • Franklin’s Gull
  • White-faced Ibis
  • Black-crowned Night-heron
  • Black Tern
  • Caspian Tern
  • Common Tern

Secondary species

  • California Gull
  • Double-crested Cormorant
  • Ring-billed Gull
  • Western Grebe
  • Eared Grebe
  • Red-necked Grebe
  • Cattle Egret*

Pelicans and Cormorants

In May 2010, Montana Fish, Wildlife & Parks (FWP) finalized a 10-year management plan for the Missouri River, from Three Forks to Holter Lake Reservoir (near Helena). The plan, Final Upper Missouri River Reservoir Fisheries Management Plan (upper-missouri-fisheries-plan), suggests that American White Pelicans and Double-crested Cormorants are significantly impacting fisheries on Canyon Ferry Reservoir, and that the FWP Fisheries Bureau should “[w]ork with [the] FWP Wildlife Bureau and the U.S. Fish and Wildlife Service to determine the impacts of pelicans and cormorants to Canyon Ferry fish populations. Consider active bird management strategies if research shows significant impacts to fish populations.” FWP has indicated that keeping this item in the management plan only commits the agency to studying the impact of these birds on the fishery, stating that, “[a]ny proposal to implement population management measures will require an Environmental Assessment and provide opportunity for public comment. No management action will be taken without thorough research and evaluation of bird and fish interactions.”

Montana Audubon will continue to monitor this management recommendation. Montana Audubon’s comments on this issue are HERE.

More information on American White Pelicans and Double-crested Cormorants appears below.

B03-Pelican.American White3_smallPelicans

American White Pelicans are native birds that summer generally in the great plains and intermountain west, as far north as northern Alberta and Saskatchewan. They winter along the southern coasts of the United States through Central America.

Pelicans are colonial nesters, and breeding colonies typically are located on islands in lakes or reservoirs (to avoid mammalian predators). Colony sizes range up to 7,500 nests. The number of colonies, and the number of nests per colony, fluctuates from year to year. For example, Medicine Lake National Wildlife Refuge, located in northeastern Montana, had 1,690 nests in 1987, 3,370 nests in 1989 and 2331 nests in 2016.

Information on the types of food consumed by pelicans is limited. From anecdotal and circumstantial evidence, it is clear that pelicans will east many kinds of fish, as well as amphibians and crayfish. Specific prey species documented by direct observation or by finding fish tags include: carp, suckers, chub, trout, walleye, pike, and bigmouth buffalo. Montana Fish, Wildlife & Parks has looked at the diet of pelicans on Canyon Ferry Reservoir. Of the pelicans tested, the majority of their diet (upwards of 90%) was carp and/or crayfish. These pelicans occasionally also ate rainbow trout, and a few other species.

In Montana, American White Pelicans are considered a Species of Concern; these are native species that are at-risk due to declining population trends, threats to their habitats, restricted distribution, or other factors. This species is protected by the Migratory Bird Treaty Act of 1918. Pelicans declined in the mid-1900s because they were vulnerable to the spraying of DDT, endrin, and other organochlorides in agriculture, as well as widespread draining and pollution of wetlands. Montana has only four places in the state where pelicans breed: Medicine Lake National Wildlife Refuge, Bowdoin National Wildlife Refuge, Aarod Lake, and Canyon Ferry Reservoir. Recently they have been shown to be particularly susceptible to West-Nile Virus, and the 2014 National Audubon Climate Report lists American White Pelicans as climate endangered. This is because only 9% of their summer range is predicted to be stable until 2080.


Pelican information from our 2016 waterbird surveys:

There are four known breeding locations for American White Pelican (AWPE) in Montana. Three are major colonies and one is much smaller. Nesting was documented at all 4 sites for the AWPE in 2016.  The three major sites yielded a total count of 5744 nests.  This is very close to the 2009 through 2015 average of 5810 (see table 1).  While there have been large fluctuations in the annual nest numbers at each colony, the overall totals for the three sites have remained relatively stable.

The AWPE typically nests in large colonies on an island or point that is relatively isolated from predators. The nests are shallow depressions scraped in the ground and lined with twigs and other debris. Where available, partial shade afforded by trees is preferred. Colony locations may vary from year to year depending on water levels and other factors. The timing of egg laying may vary among colonies, even those in close proximity. At Medicine Lake NWR during both seasons there were two sub-colonies, one on a large island and one on a long point from which predators were excluded with an electric fence. At the time of the surveys island nesting birds had only eggs while on the point the nests had well-developed chicks, one invariably much larger than the other, in nearly every nest. In subsequent years all nesting for the species at Medicine Lake was on the point only.  The species is known to travel long distances at times to feed during the nesting period.

Productive (meaning active nests were documented) nesting colony survey dates for this species have ranged from 5/18 to 6/15 during the eight years of this study.


b03-Cormorant.Double-crested6_smallCormorants

Double-crested Cormorants are native birds that are distributed widely across North America. These cormorants nest near the ocean, as well as in the interior of the United States and Canada. They winter along the Atlantic, Pacific, and Gulf of Mexico coasts.

Cormorants are colonial nesters. They generally build their nests in trees, on cliff faces, or on islands.

These cormorants mainly eat fish, although they also eat amphibians and crustaceans. Adults eat an average of one pound per day, usually comprised of small (less than 6 inch) bottom dwelling or schooling “forage” fish. According to a 2006 study conducted on Canyon Ferry, Double-crested Cormorants ate the following percentages of different aquatic species: 44% stonecat, 13.2% trout, 13.2% suckers, 15.5% dace, 6.6% sculpins, and 7.7% crayfish. Summarizing this information, the diet of Canyon Ferry cormorants contained approximately 87% nongame fish and 13% game fish (trout).

In Montana, Double-crested Cormorants have no special conservation status. However, this species is protected by the Migratory Bird Treaty Act of 1918. Double-crested Cormorant numbers decreased in the 1960s due to the effects of DDT, and the 2014 National Audubon Climate Report lists them as climate threatened because 21% of its summer range, and 72% of its winter range are predicted to be stable through 2080.


Cormorant Information from our 2016 waterbird surveys:

The Double-crested Cormorant is a common breeding species throughout Montana.  Nests consist of a platform of sticks in a tree or on the ground on an island.  The DCCO often nests in tree colonies with herons or on the ground within large gull and pelican colonies.  They generally breed at three years of age and nest in large or small colonies.

Nesting was documented at a total of 8 sites for the DCCO in 2016.  One site, where the species has always nested in years surveyed, was not covered in 2016.   The top three nesting sites were Bowdoin NWR with 491 nests, Canyon Ferry WPA with 215 and Freezout Lake with 173.  The 2016 total for the four key sites was 999.   These sites, all east of the Continental Divide and ranging from Freezout Lake WMA in Teton Co. to Medicine Lake in Sheridan Co., show a slight increase after the 2009-2011 period with some large annual fluctuations at individual sites.   Productive nesting colony survey dates for this species have ranged from 5/3 to 7/13 during the eight years of this study.


More information about Double-crested Cormorants can be found at:

 

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