Maryland Wood Duck Initiative Research

MWDI believes that effective resource management of nest box programs cannot occur without good data on nest use and productivity results. Obtaining and analyzing this information is critical to optimize duckling production from a given set of nest box “assets". MWDI’s research focus is generally oriented towards the establishment and use of this statistical base. As MWDI builds its state wide data base of nest box information into the “thousands”, all sorts of statistically significant analyzes will be possible.

While this data base will take years to build and perfect, the use of artificial nest boxes offers many types of “cause and effect” study opportunities that complement these potentially more sophisticated analyses. These studies can be quite simple or complex, but they help reinforce the educational aspects of nature at work.

MWDI has initiated several of research projects and is keen to start others. The principal ones include the following:

Recycled Freon Canisters

Freon Canister Open on Office deskNest structures made from these discarded metal canisters (2) have been used successfully at Federal Refuges in Iowa (Union Slough in particular) for the past 25 years. The USGS website provides plans for construction.

They are virtually maintenance free and will last over 20 years. The “all-in” cost is less than $5 each for assembly hardware.

MWDI raised concerns about Maryland’s more southerly latitude than Iowa and whether “our” wood ducks would use them. Most people we’ve spoken to have universally indicated that the plastic cylinders sold by Ducks Unlimited did not work.

2005 Research Projects & Results
In 2005, MWDI installed 6 canisters in 4 separate project locations in Maryland and conducted a heat test placing a box in the shade after cutting vent holes in it and painting it light beige. The spring was relatively cool that year and even in July, the inside temperature of the canister never exceed 96 degrees and the highest inside temperature was 7 degrees above the outside level. (106 degrees being the upper limit possible for egg survival.)

Of the 6 field canisters, 5 were used and 4 hatched. The unsuccessful nest was in full incubation with a normal clutch but the hen was overwhelmed by an ant infestation and abandoned the nest. Two canisters were placed in generally high use wood duck areas, representing new capacity in each project where placed. Of the others, two were in new project area and two in a moderate use region. This was most encouraging.

2006 Research Projects & Results
Freon Canister Wood Duck Nest Box Used in MWDI experiment
In 2006, 28 canisters were installed although only 18 were determined to be functional as nesting material had not been provided. Water conditions were also very poor and many canisters were in dry habitat that was typically flooded. Of the14 functional nests, 4 were used and hatched. In one project area, 2 new wood and 2 canisters were placed in the same wetland (although visually hidden from each other) and the wood ducks used the 2 new wood ones and not the canisters.

Field acceptance is still considered favorable although it is MWDI’s perception that, other things being equal, in new habitat use areas, wood ducks will prefer wood over metal if given a choice in the near term. Field trials will continue.

Heat Test Experiment - Freon Canister style and Traditional Wood Duck Nest BoxesManufacture using a plasma cutter will also be tested further as this seems to be the easiest way to cut off the tops and bottoms and cut out the entrance hole and bolt holes. Supply of canisters is not a limiting factor. MWDI has sources defined to make hundreds.

Heat Test Conducted
To independently analyze the heat buildup issue, Donny McKnight, of the Harford Christian School, agreed to establish a heat test under more controlled circumstances than that done by MWDI and to monitor a wooden box in the same environment. Donny’s results will be published soon. He has documented that heat buildup was not an issue limiting the prospective widespread use of recycled canisters in a shaded environment.

Pros & Cons Indicate Longer Term Evaluation Worthwhile
Freon canisters are harder to fabricate than wood boxes and they are not “traditional,” but they are very cheap and the maintenance benefits are such that longer term evaluation is considered to have real merit.

Nest Data Quality vs. Time

Reasonably accurate information on nest box productivity is important, especially in new programs or where a proactive resource management approach is desired. Productivity results and nesting behavior can be hard to interpret especially without a good egg membrane count and to a lesser extent, without relatively fresh down and unhatched eggs left in their immediate “post-nest” natural position.

Interior of Wood Duck Nest Box with broken eggsLate winter and early spring inspections often miss or misinterpret the “clues” left behind as residual nest information may change. For example, membranes are eaten by inspects or removed by other nest users, down gets scattered, wet and matted, old eggs break/get broken or substantially altered to mask potential nest strife or predation.

In more than one project area where interim nest inspections were initiated as compared to annual, early spring inspections, MWDI determined that under-counting of duckling production was substantial. Further, nest strife and snake predation, in particular, had not been recognized as problems affecting overall productivity.

In an attempt to document more fully the impact on productivity estimates that the passage of time causes, MWDI established 75 “control” nests in 2006 where nest productivity is confidently known. These nest boxes will be checked again in early spring 2007 and another hatch result will be estimated by a different inspector and the results compared. Unhatched eggs were removed so it will basically be a membrane versus membrane count.

This research will be expanded to encompass assessment of nest strife and other qualitative factors to try and document better the merits of interim and prompt inspections following the nesting season and to help determine where such efforts are not necessary.

Wood Duck Egg, Down, and Egg shells on Graph PaperFor mature nest programs where only one box visit has been made, MWDI encourages sponsors to conduct a nest maintenance inspection in mid-late summer instead of early spring to obtain a reasonably accurate perception of nest results before other events alter the data. Nest materials can be changed then and left for the following spring season. The weather is also nicer and there are more natural things alive to see (and potentially avoid!).

On new programs or in mature programs where actual results are not really known, an interim inspection mid-nest season and then a late summer inspection is strongly encouraged to help establish the overall status of the program. Once this data reference is known, subsequent inspection frequency and timing can be altered down to the individual box in many cases.

However, in MWDI’s brief tenure, there has not been one nest program that has not been favorably enhanced after conducting an interim and then another nest inspection in late summer.

Starling Deterrence – Horizontal Nest Box Use - By Cliff Brown

Wood Duck Nest Box Interior with both Wood Duck & Starling eggsIn late 2004, after receiving approval from Chesapeake Farms, Dupont’s Kent Co. Conservation Easement, Agricultural and Wildlife Research property, it was explained during the initial field tour that starlings had completely overwhelmed the boxes situated in the primary wetland reservoir and duckling production was zero from 18 boxes.

All boxes were cleaned ahead of the 2005 nest season. It was hard to believe that they had been cleaned the prior year. Debris was over 18” thick in most boxes and many old eggs in layers were present. I thought this represented several years of unsuccessful nest attempts. Silly me.

Wood duck use (as subsequently determined by several interim nest checks that spring) was close to 300%!! At each nest attempt, ducks would lay several eggs and then starlings would enter and dominate. Routinely, after a starling hatch or while starlings were attempting to conclude their nest, other wood ducks would try to start another nest. The once cleaned 24” deep box would have a duck / starling “lasagna” – a stack of intermixed duck eggs, starling nest material, more eggs, more starling sticks, etc. but never a successful wood duck hatch. More than 600 eggs were thrown away.

Horizontal Wood Duck Nest Box Used in ResearchI had read from the Wood Duck Society newsletters how bad starlings could be. I had not experienced this problem in our private 4 year old program. I was amused to read about starling traps and other forms of harassment but nothing seemed very practical for a necessarily remote and passive deterrence technique. I recalled seeing reference to an old study where horizontal nest structures made out of 12” galvanized pipe had been successfully used. I then learned that Frank McGilvrey, retired USF&WS but still active as volunteer project manager at the Patuxent Wildlife Refuge, was one of the authors. I met Frank, got to observe horizontal boxes up close and immediately made and installed some either made from 12” x 24” sewer pipe (12” galvanized material was not available) or horizontal rectangles made by flipping several of the older wood boxes sideways and adjusting the openings.

Convinced that I could not do worse than zero ducklings, Chesapeake agreed that for the 2006 season, besides trying eight horizontal nests, we close the other vertical boxes in the reservoir in proximity to each other and add new boxes all along the woods-wetland margin surrounding most of the wetland. The concepts were to eliminate all starling housing, assuming the horizontals did their job, to offer wood ducks the woods’ margin boxes as an alternative house that would be less attractive to starlings as generally represented in other literature. Net capacity was temporarily reduced in this wetland but we had installed other new boxes elsewhere on the property and had hoped these actions might help their utilization. (It was over 90%).

Three of the 8 horizontal boxes were used and hatched. Starlings did not enter any of them. Some starlings perched on the entrance on one horizontal long enough to “poop” extensively but never went in. The other woods’ margin boxes were almost all utilized and had either normal or relatively small dump nests. We opened 4 of the vertical boxes in late April. Two had successful wood duck hatches without starling interference and two were starling nests. All of the horizontal nests had been examined by wood ducks as rounded depressions in the nest material clearly indicated.

Interior of Horizontal Next Box with eggs Perceptions thus far are that horizontal nests work and offer an excellent way to thwart starlings. Based on only one season’s observation, wood ducks do not seem to prefer these nests over vertical; however, in heavy use areas, they appear to use them readily. (3 other horizontal nests were installed in non-starling prone areas. The nest boxes were examined; one had a drop nest but none were successfully used).
Research will continue and expand in 2007. After the initial installation, I learned a few weeks later in the wooden horizontal boxes that we needed to make sure the back end of the horizontal nest was relatively dark to help entice woodies to use them. Our opening holes in the wooden horizontal boxes were also not 4” x 11” as recommended in the article which I also got belatedly. The wooden rectangle horizontal openings (4 of the 8) were roughly 6” x 8”. Nest use was split evenly between round sewer pipe and wooden horizontals. Thus, our quality control was lacking somewhat but we’re poised to rectify these minor aspects for next season.

It was also pointed out by Frank that he is fairly confident that it is the size of the entrance hole and not the amount of light allowed into the box that deters starlings. Patuxent Refuge continues to use horizontals as part of their housing mix and enjoys about 65% use on their 40 horizontal boxes without any starling issues.

Double vs. Single Box Effectiveness

Experiment with double wood duck nest boxMWDI has begun a multi-year study to document nest use & productivity from double box configurations compared to single box mounts. Previously, it was an accepted resource practice to mount multiple boxes on single poles due to cost and maintenance efficiencies as the detrimental impact on productivity caused by increased nest strife, lower hatch rates and increased abandonment were not readily appreciated. Clustering (i.e., placing boxes in relatively close proximity to each other) whether single and double box mounts was also an accepted practice for similar perceived efficiency reasons.

Experiment with wood duck nest boxToday, while there is a greater appreciation of the detrimental effects nest box clustering may have, the use of double box mounts is still a common practice. As a result, MWDI felt that it would be useful to evaluate whether this practice had a positive, neutral or negative productivity impact and under what circumstances it might be cost effective.

Related to this analysis, especially where overall nest dumping and strife are known to exist, MWDI will increasingly experiment with delayed or staggered nest openings of one of the double mounted boxes to see if this type of “de-clustering” approach might yield beneficial results.

These are the type of studies that are feasible and will become more statistically significant as the state wide data base grows. Additional private program participants are sought to join this study. Site specific and sponsor data are kept confidential.

Bee Deterrence

A Potential Hazard - Bees Nesting inside boxesAs an example of a relatively simple "cause and effect" study,    MWDI had read that soap rubbed on the inside roof on boxes thwarted wasp nests. We tried it on about 50 boxes and it did work if applied fully to cover the roof and if thick enough to fill the rough wood seams. Some bees made nests on the side panel but these and any other nests were all small (1-3 bees). We also found that it was much easier to rub the roof before assembly so all corners could be covered and knuckles were saved. We’re not sure it was necessary to use deodorant soap as advertised but we did anyhow…Irish Spring!