At night, put light where it is needed, keep it warm, keep it dim.
Night Lighting Ecology - Learning Objectives
When we use carefully aimed, dimmer lights - instead of excessively bright, glaring ones - we can see better, maybe even see the stars. Balance and restraint is the key to most things in life, and restraint also applies to lighting, especially in our night sky.
Visit my Dark Sky page at TOlighting.com
Notes from IES Mission Meeting - Feb 19, 2016 - Light Pollution and the Ecological Consequences of Artificial Night Lighting by Dr. Travis Longcore
1. Is the lighting needed?
2. Reduce duration.
3. Reduce intensity (Full moon is 0.01 footcandles or 0.1 - 0.3 lux)
4. Direct light to necessary targets only.
5. Stop using full spectrum lamps outdoors, use Amber.
Further Reading: Artificial light pollution: are shifting spectral signatures changing the balance of species interactions? http://onlinelibrary.wiley.com/doi/10.1111/gcb.12166/full
High-intensity urban light installation dramatically alters nocturnal bird migration 
Birds are attracted to light.
High-intensity artificial lights attract birds and disrupts their migration patterns. Birds are observed circling lighting and vocalizing, wasting energy otherwise spent on migration. Birds become disoriented, exhausted, and many die.
In a recently published study with data collected between 2008 and 2016, during Tribute in Light, up to 20 times the normal density of birds have been observed, they disperse, when the lights are shut off for 20 minutes.
Here is a link to the study, High-intensity urban light installation dramatically alters nocturnal bird migration, is provided in the footnotes.  and an article in International Dark Sky Association newsletter. 
Bridges with vanity lighting scare fish from migrating.
In Redding, California, there is a foot bridge named Sundial Bridge. One study shows that during fish migration season, the numbers of fish passing under the illuminated bridge were staggeringly low compared to before the lighting of the bridge.
The City of Redding has posted this page, https://www.cityofredding.org/departments/parks-and-recreation/light-the-sundial
Seals have become a charged problem, Canwest News Service, Published: Sunday, April 20, 2008
... Even under perfect conditions, only one per cent of Chinook salmon smolts that swim down the Puntledge and into the Strait of Georgia return three or four years later to spawn.
The presence of crafty, voracious harbour seals makes their chances of survival even worse.
According to Ottawa, a herd of determined seals has been trolling the Puntledge for years, eating up almost every baby summer Chinook in sight.
Some 50 seals have learned to swim up the Puntledge and hide in the shadows under a bridge that serves the city of Courtenay. Streetlights that line the city's Fifth Street bridge illuminate the unsuspecting smolts as they move downstream at night; the seals set their sights, open their mouths and feast. 
Ecological Consequences of Artificial Night Lighting
Ecological Consequences of Artificial Night Lighting
By Catherine Rich and Travis Longcore
While certain ecological problems associated with artificial night lighting are widely known-for instance, the disorientation of sea turtle hatchlings by beachfront lighting-the vast range of influences on all types of animals and plants is only beginning to be recognized. From nest choice and breeding success of birds to behavioral and physiological changes in salamanders, many organisms are seriously affected by human alterations in natural patterns of light and dark.
Ecological Consequences of Artificial Night Lighting is the first book to consider the environmental effects of the intentional illumination of the night. It brings together leading scientists from around the world to review the state of knowledge on the subject and to describe specific effects that have been observed across a full range of taxonomic groups, including mammals, birds, reptiles and amphibians, fishes, invertebrates, and plants.
Ecological Consequences of Artificial Night Lighting provides a scientific basis to begin addressing the challenge of conserving the nighttime environment. It cogently demonstrates the vital importance of this until-now neglected topic and is an essential new work for conservation planners, researchers, and anyone concerned with human impacts on the natural world.
How to support Dark Sky?
International Dark Sky Organization www.darksky.org
Find a chapter near you and learn more.
Become a citizen-scientists to measure & submit their night sky brightness observations.
https://www.globeatnight.org/ In 2017 citizen scientists from around the world contributed 15,382 data points. Globe at Night is a program of the National Optical Astronomy Observatory, the national center for ground-based nighttime astronomy in the United States, operated by the Association of Universities for Research in Astronomy (AURA), under cooperative agreement with the National Science Foundation.
Be sure to read the article about Davis LED Retrofit Zombie Lights, By James Benya
European Dark Sky Places Conference
20-22 September 2017, Gatehouse of Fleet, Dumfries & Galloway, Scotland experts gathered for Europe's first dark sky conference.
"...The stars are not just used by us in lots of different ways but they are also used by migrating birds and everything else to actually navigate by.
Light pollution is causing all sorts of health issues and there is lots of research out there saying that we are only just beginning to see the long-term effects of that. He said there were also environmental issues related to energy use." Forest Enterprise Scotland visitor services manager Keith Muir said a lot had been achieved since the park reached dark sky status.