Janae McGee

1. Brood parasitism in CRW wood ducks: What type and location of nests are most susceptible to brood parasitism in the Cache River Wetlands? Janae McGee

2. Wetland Loss • Humans harness water for their own purposes, (e.g., maintaining our water supply or using water systems for transportation). • Negative effect on the ecology of river systems and their corresponding wetlands • Over half of the wetland ecosystems existing in the early 20th century have been lost in North America, Europe, Australia, and China • Conditions such a decline in water quality, depletion of ground water, loss of diversity and a change in the natural flooding have resulted. • Stream flow plays a big role in healthy rivers and shouldn’t be manipulated.

3. Natural Flow Regime • Natural flow regime helps sustain native biodiversity and ecological integrity. • Over $70 billion dollars have been spent in North America in the last twenty years to correct . • Major rivers have been affected by the placement of dams and levees • Roads and canals has altered the drainage of wetlands. • Levees have prevented flooding   • Dredging canals can change flow patterns

4. Flood Pulse Concept • Combination of the river channel and floodplain is important • Production, decomposition, and consumption are lead by the flood pulse and the rise and fall of the water. • Wetlands function as natural sponges that trap and slowly release surface water, rain, snowmelt, groundwater and flood waters • Trees, root mats, and other wetland vegetation also slow the speed of flood waters and distributes them more slowly over the floodplain. • This combined water storage and braking action lowers flood heights and reduces erosion. • The holding capacity of wetlands helps control floods and prevents water logging of crops. • Short, unpredictable floods occur in these low order streams or heavily modified systems with floodplains that have been levied and drained by man. • Desire to turn flood plains into agricultural farms or living areas for residents has made it hard to return rivers to their natural course of flooding. • Water regimes need to be in sync with seasonal climate and water flow in order to restore wetlands. • Organisms have specific adaptations which differ for each stage of their lives that allow them to tolerate the wet/dry conditions that are a part of a flood-pulsed environment

5. Biodiversity Loss • Human domination has an effect on the survival of species that live in that area. • There is a push for reserved land for wildlife. • Survival of species is an interdependent situation and both the community and the ecosystem must be considered when making decisions • Extinction is a fairly common occurrence • Habitat destruction is a cause of extinction and just because a species is dominated doesn’t mean it will survive because animals are interdependent on each other

6. History of Wood Duck Decline • Wood Duck population dangerously low in 1st part of 20th Century Causes • Ducks were overly hunted • Drainage of timber bottomlands and swamps Laws Passed • Federal Migratory Bird Act of 1916 • Migratory Bird Treaty Act of 1918 • The wood ducks enjoyed complete protection from hunters until the year 1941.

7. History of Wood Duck Decline • 1938 --waterfowl nesting habitats approaching saturation point. • Signs that suitable nests were in short supply- nests in chimneys, poor cavities and in hawks’ nests. • Legal protection had allowed their population to greatly increase from the previous low numbers.

8. Recovery over the years…….. • 1941 hunters in fifteen states were permitted one duck per day. • 1942 All states allowing one duck limits • 1950’s Wood ducks suffer some fluctuations • 1954 Wood Duck Hunting season closed in Mississippi Flyway • 1955 One duck allowed again • 1956-1958 Season closed again • 1959 Reopened season with one duck limit • 1963 Limit increased from one to two ducks • 1964 – 1974 Statistics prove that the population had officially recovered although will likely never return to numbers of the 1800’s .

9. Wood Duck Habitat • Wood Ducks are freshwater species which occupies forests associated wetlands. • Live in the contiguous United States with some crossing into Southern Canada and their greatest population is seen east of the Great Plains. • Spend their winters in the southern region • Nests in trees near water, directly over water, or up to 2 km away. • Thrive in bottomland forests, swamps, freshwater marshes, and beaver ponds • Common along streams of all sizes, from creeks to rivers • Choice of habitat is also due to their diet; seeds, fruits, insects and other arthropods. • Plant materials make up 80% of their diet

10. Nest Boxes • Federal and state laws caused populations to grow faster than the forest could age and provide natural nesting cavities. • Wood duck houses began to be placed in forests as a solution to this problem in the late 1930’s to compensate for the natural sites.

11. Nest Boxes • Houses are a great research tool in understanding the biology of nesting. • They help to involve the general public in simple wildlife management. • Wisconsin’ Department of Natural Resources did a study which found that wood houses are not cost effective for wildlife management in areas with ample amounts of nesting sites, but should be implemented in areas where natural cavities are limited.

12. Wood Duck Reproduction • Wood Ducks pair up in January • When looking for a mate, males swim before a female with wings and tail elevated, tilting their head backwards for a few seconds. • Males may also perform ritualized drinking, preening, and shaking movements.

13. Wood Duck Reproduction • A hen lays one egg per day • Wood ducks have an average clutch size of 9–12 eggs • When the entire clutch of eggs has been laid, the hen will begin full-time incubation. • The eggs then have a good chance to hatch together on the same day. • During the incubation period, the hen will leave the nest box twice daily to feed for about 30 minutes. • Incubation period usually between 28 and 32 days • Entire clutch hatches in less than 24

14. Wood Duck Reproduction • The hen will leave the nest box with her new brood on the first morning after the initial egg was hatched. • After surveying the terrain for predators, she flies down to the ground and begins calling out the brood. • The duckling will then jump out of the nest regardless of its distance from the ground • Getting her new brood safely to a pond for food and cover is essential for their survival.

15. Broods • The Wood Duck is the only North American duck that regularly produces two broods in one year • Studies have found that over 90% of the deaths of ducklings happened within the first two weeks after hatching. • The highest losses occurred during the first week

16. Broods Brood counting can be difficult. • the breakdown of bonds after the fifth week • Hens usually abandon hatchlings at 6 weeks • Ducklings may leave brood • Hens accept strange ducks • Mixing of different broods • Forest density • Wood Duck Mobility

17. Parasitism • Intraspecific parasitism in wood ducks is known as brood parasitism; a method of reproduction seen in birds that involves the laying of eggs in the nests of other birds of the same species and the eggs are left under the parental care of the host parents. • Parasitism has been found to occur in 60% of waterfowl in America, and is very common among wood ducks

18. Advantages Brood Parasitism • Parasite Advantages • Increase reproduction without having to take the time and energy to incubate eggs or provide parental care. • May have a successful clutch despite limited nest sites if another bird takes over their eggs for them. • Host Advantages there is safety in numbers; the more ducklings in her group the more possibility for survival

19. Disadvantages of Brood Parasitism • Parasite Disadvantages • Increased time and energy necessary for them to find nests with eggs at an appropriate stage of development for them to dump their eggs inside. • The hens that are at the nest site may try to defend their nest with physical aggression • Reduced hatchability of their eggs once mixed with another bird’s clutch. • Host Disadvantages • They could have reduced hatching success, the survival of their own offspring may be reduced with the added numbers in the nest, • Hen herself may have increased physiological costs from the process of incubation and giving parental care

20. Brood Parasitism • More prevalent in species that nest in cavities because safe cavities are in short supply due to destruction of bottomland forest. • Cavities are also susceptible to parasitism because some wood ducks will return to the same cavity year after year. • If another bird is in their home site they may lay their eggs there anyway • Cavities are often located high in trees which make them easily seen by other wood ducks at a distance. • Studies have concluded that parasitism can be reduced by mounting more man-made wood boxes to combat the issue of limited nesting sites.

21. Study Site • Cache Wetlands • Both upland sites and open water sites in the LCR and the UCR • This includes Heron Pond and Boss Island in the UCR • Section 8 Woods and Bottomland Swamp in the LCR.

22. Objectives Hypothesis • Determine if brood parasitism is occurring in the CRW • Examine the potential of brood parasitism to serve as a biological indicator • If there is a limited amount of desirable nesting locations then the wood duck community will participate in brood parasitism • Nesting sites which are at a higher elevation will have higher rates of brood parasitism • Nesting sites that were available during previous years will have higher rates of brood parasitism

23. Methods • Visit Cache during the weeks of June 18th to the 29th • I will climb up to the nest, pull back any down feathers used by the wood duck to cushion the nest and count the number of eggs. • I will record how many eggs are found in each nest, where the nest is located (including place and height), and what type of nest it is (cavity or wood box) and if the nest was in place the previous year • I will count any nest with more than 12 eggs as one that has experienced brood parasitism.

24. Methods Cont…. • I will sample 100 nests over the 2 week study. • Twenty-five nests at each site will be included in my research. • In order to reach the nest, I will use a canoe, waders and ladder. • I will use a survey table to record information about each nest.